A Hybrid Heat Pump System

The more I look into the idea of an air-sourced heat pump heating system the more it appeals. In particular, the idea of heating my home without burning fossil fuel to the greatest extent possible is within grasp and there are even solutions out there that could renewably source the gas I burn. More on that later.

A chap from the prospective installation company came to measure up the house in order to calculate its space heating requirements. He went through each room with the tape, drawing a little plan on his clipboard and adding numbers as he went. He then discovered what a sad git I am! (Sad being a modern term for a geeky person who is deeply happy but few understand her or him, and their compulsive ways.) I introduced him to the spreadsheets with which I have documented our daily energy usage and generation over nearly ten years of patient data gathering. He seemed impressed and I glowed with pride. All we had to do was add up a complete year of gas consumption in kWh. The answer was 23,650kWh of energy. With an estimate of 20% being used for water heating, this led us to a figure 19,000kWh as representing our space heating requirements for a year.

He suggested that the way forward is to replace our existing combination boiler with a Daikin Altherma hybrid heat pump system. This consists of two units that work in series to supply the heating and water needs of the house. Most of the space heating comes from an outdoor heat exchanger, like an air-con unit in reverse. This can extract up to 8kW of heating power from the outside air and it will do this right down to about 3°C. This covers a lot of the typical winter weather in the West of Scotland which is characterised by relatively mild, moist air coming off the Atlantic Ocean on the prevailing south-west wind. The outdoor unit measures 735mm x 832mm x 307mm and is sited at least 150mm away from the house wall just outside where the boiler is.

A graphic from Daikin's brochure to illustrate how the heat load required by a typical European house can be met by an air-sourced heat pump. For the milder Scottish climate, I suspect this curve would move to the right somewhat.

When the temperature goes below 3°C, the indoor gas condensing boiler comes into play to augment the output from the heat exchanger. The two sources of heat are blended under computer control which also takes into account the tariffs for gas and electricity, on the assumption that the user has entered these values. At around -4°C or less, the 33kW gas boiler takes over completely. Although slightly larger than our existing unit, this boiler will fit into the available space. The system so far described is entirely capable of working through our existing system of 13 radiators. But that's not the plan.

Our home was built in 1970 and a builder extended it in 1990. We believe this was done purely with the intention of making money out of it and thus, shortcuts were taken. For example, the back room extension has a floor suspended on old scaffolding battens instead of conventional joists. One imagines a pile of these were lying around and so they were pressed into service instead of having to buy new wooden joists. They do the job perfectly well but they illustrate the shortcuts taken.

The 13 radiators I have are a mixture of very old single panel units and relatively new double panel units. I'm guessing some are original with the house, nearing a half century old, and some had to be bought in when the extension was done and thus are over a quarter of a century old. There is one further small one that we added about 15 years ago.

All these radiators are fed via a mixture of 8mm microbore copper piping (popular in the 1970s) and 15mm small bore pipes with a little bit of plastic piping for our additional radiator. To the guy from the installation company, this was less than ideal. It is apparently difficult to properly balance the flow rates through the system when there are pipes of different sizes all over the place. Moreover, the heat pump system can work more efficiently at a lower temperature than conventional systems and therefore benefits from having larger radiators in order to transfer sufficient heat to the rooms. Given the advanced age of the system's components, we decided that the job should include the complete replacement of all radiators and their associated pipework. That way, we start with a clean sheet and a single point of contact should there be a problem with the heating system as a whole.

Finance

Our initial quote for this work comes to a shade under £11,000. Three quarters of this can be covered with an interest free loan from the Home Energy Scotland renewables loan scheme. This is paid back over a term up to 12 years. Consequently, the up-front cost to us would be £2,745, an amount that compares favourably with the cost of simply replacing our boiler with a reputable condensing unit.

To further help with the overall cost of the system, I ought to be able to take advantage of the Energy Saving Trust, Scotland's Renewable Heat Incentive (RHI) scheme. I'm told that the way this will work is that for a period of seven years, quarterly tax-free payments will be made to me based on readings from meters that monitor the gas and electricity used to run the system. The installation company has given me an estimate of how much this would be, and their figure is £6,860. This is £1,373 less than the loan so that, over the piece, the cost to me would be £4,118.

But that's not the whole story. The calculations by the installation company suggest that my running costs for the system will reduce by £341 per year. If we add that over the seven years of the RHI scheme, then we would have saved £2,387. Moreover, this assumes that all the electricity used to power the system has to be bought. It does not take into account the fact that for substantial periods of the year during daylight hours, there can be a surplus of electricity coming from my solar panels that can be used to help run the heating, something that does not happen at the moment. Typically, we run our heating from late October to springtime. In the depths of winter, it is very rare that the panels produce spare power but from mid-February to late October, it is much more common.

Living with the system

Installation of such an air-source heat pump system might change our usage habits. With our gas-only current system, we tend to bring it on only when we perceive it is really needed in an effort to save gas. This means that throughout the heating season, it is on for 3 hours in the morning, 3 hours in the late afternoon and three hours in the evening. In midwinter, the house is relatively quick to cool and there comes a point when we just force it on full time.

I suspect that controlling a heat pump system would be quite different. Our current system has few controls and what there is depends only on each room's thermostatic radiator valve (TRV). In the new system, there would be a central thermostat/control panel, probably located in the centre of the house. Additionally, the (new) TRVs would allow control of an individual rooms but the system would work to maintain a temperature at the control panel. The heating characteristic of an air-source system is different because it is less responsive. From all accounts it is better to leave it on most of the time and instead, programme a desired temperature profile for the day/night cycle. Moreover, it might be easier just to leave it on through most of the year. As the temperature warms through May and June, the demands on the heat pump would lessen while there would be far more available solar energy to power it. I can imagine only turning the heating off for two or three months in summer, and if its control system is good enough, maybe never.

Insulation

As an additional but separate job, I'm going to get the installation company to insulate the floor of the back room extension. This room is my office and has three walls to the outside. When it was built, barely 2cm of insulation was added to its roof space and none beneath its floor. Though it has two radiators, it always has a cold feel in winter. Last summer, I cut a hatch in its ceiling and laid 20 or more centimetres of insulation into its narrow roof space. This has helped a little but since the two radiators are to be changed anyway, along with all their pipework, I thought this to be a good opportunity to insulate the floor. Unfortunately, there is inadequate space available below the floor to carry out this work from beneath so I've asked for a quote to lift the room's entire floor in order to add an appropriate layer of insulation between the joists.

The next task is for the installation company to come out and finalise the plans. Additionally, I need to fill out the loan application form that arrived from Home Energy Scotland.

Gas from grass

It can be pointed out that while a hybrid heat pump system ought to hugely reduce my dependence on fossil fuel, it doesn't exactly cut it out completely. This is perfectly true but I see a possibility here. I recently watched a video on YouTube produced by the excellent Robert Llewellyn for his 'fullychargedshow' channel (though it is not released yet). In this, he interviewed Dale Vince, the boss of the environmentally aware energy company Ecotricity. Like other power companies, they allow you to buy both gas and electricity from them but most (95%) of that gas is sourced from fossil reserves.

What Vince wants to do is arrange a series of 'Green Gasmills'. A 5MW example would be supplied with grass grown in 1,200 hectares of surrounding land, much of it from marginal land. Farmers are already well practiced in grass growing for silage production as animal feed. Anaerobic digestion would be used to break down the grass and release methane. The gas is harvested, scrubbed to make it compatible with the national gas grid, and the remains would be returned to the fields to act as natural fertilisers for the next growing cycle. Such a facility would supply enough gas for about 3,500 average homes; more if hybrid heat-pump technology achieves more widespread adoption. Ecotricity hope to install these across the country. And, unlike a fracking site, with its limited lifetime, a Green Gasmill will keep producing gas indefinitely.

The downside for me? Gas and electricity from Ecotricity is more expensive than my current supplier, EDF. This is especially true since I make sure to renew my tariff offer from EDF. With Ecotricity, I would gain a £40 discount for having an electric car and some free access to their motorway-sited electric car chargers; both of which are small beer. Nevertheless, I feel minded to help Ecotricity along by signing up to them.

Renewable heating

So far, in my bid to have a modern twenty-first century lifestyle that's leans towards being sustainable, I've acquired solar panels to supplement my electricity consumption, and I have an electric car in order not to burn any more fossil fuel than I have to while getting about.  Now I want to take the next step because I want to deal with our house's heating.

Here's the picture thus far. We live in an average house built around 1970 when insulation was barely thought about. It was extended in 1990. We have fully insulated the loft and the roof space above an extension room. Our floors are not insulated and, because access to the underfloor space is extremely difficult, the only way this is going to happen is to empty all the downstairs rooms, lift their carpets and then their floorboards. Where we can, we have had the cavity walls insulated.

16.5 years ago, we installed a 24kW Vokera Linea combination boiler and water heater. This burns gas to drive a central heating system of 13 radiators on a hot water circuit; pretty standard stuff in the UK. One of those radiators is permanently switched off. The water heater comes on when it senses demand, burning gas to heat water as required. Because of this, we dispensed with the hot water storage tank that the house had at that time.

The boiler has been annually serviced by British Gas on a Homecare agreement since it was new and it is reasonably reliable. However, I'm not prepared to wait until it fails on me before getting it replaced because that will force me to make that replacement rashly. In the knowledge that the boiler is approaching the wrong end of the 'Bathtub Curve', we have decided to start planning for the changeover now.

For those unaware of the bathtub curve, this is a theoretical curve that plots the reliability of complex mechanical systems as time goes on. At first, there is likely to be a rash of failures. These will mostly be due to manufacturing or installation defects and it is these that the one-year guarantee is meant to catch. It is the steep end of the curve but then we enter a long period of reliable operation. The systems are doing what they were designed to do, within the timeframe they were expected to do it. But as they age, the probability of failure gently begins to rise as parts wear out or extreme circumstances exceed the ability of the system to cope. The shape of the graph is like the cross-section of a bathtub.

In the case of the boiler, heat exchangers are likely to corrode, gas burners may clog up, sensors might fail. Moreover, an old boiler is never as efficient as a new one, given the improvements in boiler design over the years. The Vokera Linea was 77.5% efficient when new. A new Worcester boiler is over 90% efficient.

The big question then is how to upgrade the system. There are lots of options but I'm tending to focus in on two.

Boiler changeover

The easiest solution is simply to swap my old combi boiler for a new condensing one. The Worcester brand seems to have gained a high reputation in this regard. If I do follow that path, then I'll likely follow the advice I've been given to get one that has a 30kW rating instead of my current 24kW. The feeling seems to be that the Vokera is struggling, given the size of the house.
Although a new condensing boiler will reduce the gas we consume for heating, there are solutions that can take this reduction much further. Most seem to be impractical for our house but there is one that might work.

Solar thermal

This consists of an array of evacuated glass tubes mounted on a roof. The tubes house collectors for the Sun's infra-red output and the resulting hot fluid usually heats a storage tank of water. That's as fine as far as it goes but it would mean installing a new storage tank. Further, it would not be capable of heating radiators and, worse still, it works well at the wrong time of year. From May to October, when the Sun is most capable of heating water, I've got no need for it because my central heating system is shut down.

Environmentally sourced heat

The environment around us is brimming with heat energy. If it wasn't, we'd all be frozen blocks at zero Kelvin (-273°C). Even on what we call cold days, there is plenty of heat around us. It is just that it is low-grade warmth. If we could gather this energy and concentrate it, it would provide an inexhaustible source of heat for our homes. Amazingly, we can achieve this by using the same principle of heat energy transport that is used in refrigerators and air conditioning units. These work by having a compressible fluid and a compressor. The fluid flows around a circuit absorbing heat in one place and giving it up in another.

If a gas is compressed, it will heat up. A good example is a bicycle pump with the outlet blocked. As a volume of air, maybe 25cm long, is compressed into a much smaller volume, the end of the pump can become seriously hot. This is because the quantity of heat that allowed that air to be at, say, 15°C ambient temperature has been forced into a much smaller volume. The energy is concentrated and the temperature will rise, maybe enough to scald.

If this hot, compressed gas is allowed to cool to ambient while being held compressed, then what happens when it is allowed to expand out to its original volume? The small quantity of heat energy remaining is spread through the larger volume and as a result, the air's temperature will fall precipitously.

Refrigeration works in the same way. A compressor squeezes a fluid which warms up as the heat within becomes concentrated. That warmth can be given up to the room via a radiator. The fluid is then allowed to expand within the fridge or freezer's interior. It cools markedly and begins to absorb the heat within before being recompressed and giving up that heat to the room. By the same principle, we can capture heat from the inexhaustible supply in our environment, and transport it into our houses. There are three common ways to achieve this.

1. If a body of water, preferably flowing, is to hand, then huge quantities of heat can be extracted from it. Water has an astonishing capacity to store heat energy, even when it is cold. Unfortunately, no such river runs near to our house.

2. Were the land around the house to be blessed with great green lawns, we could install a network of pipes beneath the surface that would be 'warmed' by the low grade heat within the ground. An appropriate fluid can be used to transport or pump that warmth into the home. Unfortunately, we do not possess a suitable amount of land, and anyway, such 'ground source heat pump' systems can be expensive to install.

3. Like the water and the land, the air around us can be used to supply sufficient heat to warm a house. Furthermore, it is easily accessible to an 'air source heat pump'. I'm going to investigate this source of heat as a possibility for our house.

Air source heat pump

On my Facebook feed, I've been seeing adverts from a Glasgow heating company pushing air source heat pumps so I got in contact with them looking for information on boiler replacement. The first guy that answered immediately launched into a sales spiel and I ended up with a quote for a replacement Worcester combi boiler for £3,384, including the replacement of two radiators in the coldish extension room. This seems a little high for me, but I pressed on.

As I began to query him about heat pumps, I learned some interesting stuff: A system would cost in the region of £8,000-plus. However, the UK and Scottish governments are keen to promote this technology to reduce carbon emissions and have a system of 'Renewable Heating Incentives' (RHI) which are paid out quarterly to offset the overall cost. Further, they offer interest-free loans to help with the initial outlay. It was suggested that the two schemes roughly cancel out as the RHI can cover the loan repayments and so an air source heat pump system can be installed for about £2,000. This is promising.

I was then passed to a gentleman who had a much more practical tone instead of the sales hyperbole and he explained the system to me a second time. As best as I can make out, the Daikin system they sell consists of two units. An external unit looks like an air-con right down to the large fan that dominates its volume. The fan draws air through a heat exchanger, cooling the air and warming the refrigerant which is then compressed to concentrate the heat. The extracted heat is then pumped into the house. There, it can be used to warm the central heating circuit. The system also has an internal unit that essentially consists of a compatible combination boiler so that if there isn't enough heat coming from the heat pump, it can be topped up from the burning of gas.

We now have an appointment in a week's time to assess the house and give us an accurate quote for the installation of an air source heat pump system.

Since then, I've gone searching for more information on YouTube and managed to learn a few things that may or may not be relevant. Apparently, because the warmth from the heat pump is at a lower temperature, the house needs larger radiators to get this heat into the rooms. I'll need to see if this applies to the Daikin system or whether the gas can be used to supplement the temperature.

Some of the videos I've watched show an external unit that is rather large – about the height of a man. As we would want to position ours over a narrow path, we will need to see if the Daikin unit is as large and if it can be mounted 2.5 metres above the path to maintain access.

Finally, I'm not sure this is going to be cheaper to run in terms of my fuel bill. While the gas bill drops, the electricity bill must rise. It takes 1kW of electricity to produce 2.5 to 3kW of heat. But electricity is 3 to 4 times more expensive than gas per kilowatt. At least some of the electricity would come from the solar panels.

An electric year

One year ago, I drove into a petrol station and, for the last time, filled my own car’s tank with petrol. Ever since, I have got around using 100% electric drive. Now seems as good a time as any to appraise the experience.

I’ve long since become used to jokes about only going as far as the extension cable will stretch and, in fact, I’ve noticed that those jibes have become rarefied. Indeed, the tone of queries from people has changed from fascinated curiosity of something strange in their midst, to thoughtful questioning about the pros and cons. You can tell folk are beginning to take this seriously.

What has been striking is the question I often hear when minds are already made up. “What’s the range?” It's natural resistance to change; a normal human reaction to distrust the new and gimmicky when there is a dependable means to hand that is well understood. Almost with unconscious ease, they will reach for the one property that they know will make the old ways look good. With a slight weariness, I trot out what has become a standard answer; worst case for me is about 60 miles, best case is 100 or more – it depends on many factors. And then I wait for a comment that sometimes comes, that such and such a diesel will do 500, 600 between refills.

I generally leave it at that. I’m finding there are increasing numbers of people that want a fuller appreciation of why an electric car ought to be considered. Although I’m an early-adopter fan-boy who might unintentionally gloss over the technology’s shortcomings to paint an image of clean, electric happiness, I have 52 weeks and 7,500 miles experience and I’ve developed opinions on the matter. So I’m going to lay them out.

The future

Electric driving is the future of motoring. This fact seems clear and simple. Once the kinks are ironed out (the aforementioned range and the infrastructure), it will become the obvious choice. Already, when I sit in morning queues on my way to work, the sound of ticking-over engines surrounding my peaceful, silent car, I feel that the internal combustion of organic fluids for the sake of movement seems so last century. When it seems that everyone else is oblivious to the dirty air they are pumping out with every beat of their car’s reciprocating heart, I become amazed at how capable we are of ignoring the damage to our collective health by the unnatural compounds and particulates that we are forced to breathe in for as long as we stay in a conurbation.

Electric driving doesn’t suit everyone and I realise I’m in a good position to try it. We are a two-car couple and if we need to go longer distance, my wife’s car is an able alternative. Many would be loathed to make a short range car their only choice. Surprisingly, I struggle to think of an occasion when we've opted for the petrol car. For the most part, people in cities don't do long journeys.

We have our own house with a driveway and space to install a charger. Many folk live in apartments and terraces where they cannot park on their own land and where dedicated chargers might be difficult or impossible to install. Public chargers are still few and far between and are very much a secondary source of power, even when free.

These drawbacks ought not to completely mask the delight I get from electric motoring. Road tax is free, electricity is about one fourth of the cost of petrol per mile travelled and there are instances when it is free. The car is extremely quiet and this really does make driving a less stressful task. I especially like going up hills because inclines are handled with the same quiet eagerness as any level road. This is especially true coming up my steep driveway to the house because the control I have of speed is a delight – at all speeds. Typically in a conventional car, a burst of engine noise is required in low gear to turn into the driveway and get up the hill. Now the most noise I make when arriving home from work at some late hour is the car door closing.

I don’t have a sporty car but it is astonishingly responsive. I often drive in Eco mode as much to rein back the instant responsiveness and give me and my passengers a smoother ride. It takes a very powerful car and a switched-on driver who is ready to pounce to get away from the lights faster than I do. I recently came up against this when getting caught in the left lane when wanting to turn right 160 metres ahead. A Jaguar to my right decided he wasn’t for letting me get ahead and tried to pace me as I took off from the line. I still easily pulled ahead and indicated for my junction but I sensed that he wasn’t happy at being trounced by some mid-range family car. I don’t normally do that!

On regular occasions, I’ve given friends and colleagues their first flavour of an electric car. It is remarkable to see preconceptions fall away. They say, “It’s just a car!” Then it’s, “Ooh, that’s so quiet and smooth,” as I manoeuvre out of the car park. When I get to a quiet straight road and floor it, their delight and astonishment is palpable. It’s not what they expected at all. Oh, and just by the way, I’m not putting out any noxious gases whatsoever. Just imagine our cities were full of such vehicles. Whether it’s Oxford Street in London or Renfield Street in Glasgow, the air would be as fresh as that in Glen Coe.

The direct costs

Enough of the fun and frolics. What have I had to pay for this? The first thing to say is that, as an early adopter, I’m in the sweet spot of incentives designed to attract us away from environmentally damaging machines and my costs for this car will surely not be attained in the future. The market is very good at finding ways of leeching cash out of our bank accounts and I don’t doubt that the same will be true of electric motoring once it becomes main stream. In particular, I stumbled across a leasing deal for a Nissan Leaf that was extraordinarily generous. Here’s how it came out, as best as I can decode the dealer’s paperwork from a year ago:

Retail price of car:  £22,031.58
Tax disc:  £0.00
First Registration fee:  £55.00
Less government incentive:  -£5,000.00
Less Nissan contribution:  -£3,200.00
Less customer deposit:  -£1,999.00
Total amount for credit:  £11,887.58

The credit amount comes from two sources; the guaranteed value after the 2-year lease was £10,872.82 which left me to pay £1,014.76 over two years.

I’m obviously missing a small detail because 24 payments to make up £1,014.76 yields £42.28 whereas I’m actually paying £39.99 per month for the car. In addition, this is a ‘Flex’ deal which means I’m hiring the battery at £80.00 per month which makes £119.99 per month for a rather posh (in my terms) car. In one year’s time, having had the car for two years, I’ll hand it back and walk away from the deal to see what’s available.

What about other costs? Here’s what I can come up with:

A 30-amp charger on the house was paid for by both the UK and Scottish governments. I bought a charging cable, a case for it I never use, floor mats and the first year's service. Total cost: £310.94.
I got an Ecotricity smart card for free (more on this later) and a Charge Your Car smart card for £20. I just renewed the latter for another £20.

I suppose I ought to add the cost of car hire last January when we took a full Vauxhall Insignia to Reading and back to attend a wedding. This was £226.78 plus whatever diesel we had to buy (about 90 litres). I did another long trip in October but Nissan were good on their promise and lent me a car for that journey. Add another tankful of diesel.

That’s about all of the direct costs I can think of. However, as well as the cost of electricity, there is another cost I’m aware of and it won’t hit me until I hand back the car. My £80 per month battery hire is based on an annual mileage of 5,000. In my first year, I drove just over 7,000 miles and assuming I do the same in the second year, I’ll have 4,000+ miles excess mileage at the end of the deal. The conditions of the battery hire state that these extra miles will be charged at 10 pence per mile so I should expect a £400+ additional charge. Interestingly, 10p/mile was the cost of petrol I was paying in my hybrid Yaris when getting 50mpg.

The cost of leccy

So to the cost of electricity, and this is a very hard one to determine. This is because the electricity that goes into it came from various sources. Any time I’ve had a charge away from the house, it has been free. I don’t know the exact amount, but I think it is only a small percentage – 5% at a guess. A chunk of that was our Great Spring Electric Adventure when we went to Shropshire and back last April. The electricity for that came from the Electric Highway network of chargers located at most motorway service stations.

Just this month, the owners of that network, Ecotricity, started charging for the service. However, apart from that adventure, I never tend to use the network so it isn’t a problem – at least for now. Ecotricity’s price seems similar to running on diesel. The rest of my electricity when out and about came from the Charge Your Car network which, so far, has been free at the point of charging but I pay £20 annually for the privilege.

I ought to give a shout out for three relatives who let me plug my car into their domestic supplies on a very few occasions during visits. All the rest of the energy for my driving came through the charger on my house wall – but even some of that was free. Having solar panels, if I see that the car needs a top-up and there is excess energy coming out of the array on my roof, I plug the car in to mop it up rather than allowing it into the grid. I’m getting paid for generating it either way so I might as well use it.

One way to look at it is to compare my total house consumption for the year before the Leaf with that consumed when the Leaf was being recharged.  It turns out we consumed 684 more units of electricity last year than we did the year before. That makes an additional cost of £80.44. Of course, that takes no account of other factors that affect our total electricity spend nor does it show power that came from the Sun to help the house, but it gives us something to think about. Actually, a daily comparison of the two years is interesting. At times, the two years are the same.

One other source of information was the Nissan Carwings Telematics system. If I gave permission, Nissan would collect usage statistics like miles travelled and power consumed on a daily basis. These could be viewed on their website via a username and password. Unfortunately, after a vulnerability in the system generated headlines, this hasn’t worked properly. The stats I do have were up to April and that had logged 1,100 units, although many of them would have been direct from the Sun.

To do the same distance in my last car, the hybrid Yaris, I would have spent about £700 in petrol. I think it’s fair to guess that, including the £20 for Charge Your Car, I’ve spent no more than £150 to power the Leaf.

Way to go

Electric cars are refined, civilised, relaxing, efficient and clean. They don’t go far enough on a single charge unless you can acquire a Tesla S, but that’s changing fast. The charging infrastructure is in its early days and has a long way to go but I mostly charge at home.

I don’t like the roar of an engine and the smell of exhaust fumes when going about my daily life. I don’t like pumping clutch pedals and flicking gear sticks just to massage an inefficient, antisocial, health-damaging internal combustion engine into the narrow zone in which it works reasonably well. I don’t like when every time a car slows down, it dumps as heat all the expensively acquired momentum it has rather than recovering energy to use again.

I particularly don’t like taking carbon that was locked away in the ground for the best part of a billion years and placing it into the modern environment for the sake of a little easy energy when doing so contributes to planetary changes that could be very damaging for us in the long term. It seems particularly narrow minded given that our Sun pours far more energy across the planet then we could ever use were we to wrest ourselves from the vested interests.

A year ago, I last filled my car with petrol. I really don’t think I ever will again.

Six years on solar

On 18 May, my 3.5kW-peak solar panel installation passed its sixth anniversary so I'm taking the opportunity to get a blog post out. The installation is going strong with a fairly stable output over the long piece. First, some totals:

2010-2011 - 2612.9 kWh

2011-2012 - 2403.2 kWh

2012-2013 - 2414.2 kWh

2013-2014 - 2433.4 kWh

2014-2015 - 2573.9 kWh

2015-2016 - 2514.8 kWh

That's pretty consistent with no obvious sign of any overall fall-off in performance, either due to aging or accumulated dirt. In the first couple of years, the panels were cleaned on two occasions but never since then. Yet both the best and the worst years were the first two. I suspect the regular Scottish rain is sufficient to them reasonably clean. As far as aging is concerned, the inherent variation in sunshine is too great to show up any trends.

I can see from watching a meter in front of me that, just like when they were new, the very maximum power output I ever see is between 3.5 and 3.6kW. It gives me a good sense that they are not deteriorating to any worrying extent. It bodes well for the lifetime of the feed-in tariff (FiT) arrangement I have which extends over 25 years.

Here are the graphs that illustrate generation.

Six years worth of daily generation measurements, along with a line that represents an average taken across 30 days. This average smooths out the curve somewhat.

The maximum, minimum and average generation that was seen for each calendar day across the six years, beginning 18 May.

The cumulative power generation across each of the six years, beginning 18 May.

Financial position

A question of interest to folk is whether the financial aspect is working out. The original cost to me for the system was £14,300. (I'm led to believe that a similar system nowadays would be less than £5,000.) I got a 10-year £4,000 interest-free loan from the government and the rest was funded from our own resources. My expectation was that the payback time would be 10 years and we've had 60% of that time pass already.

The feed-in tariff pays me an amount for every unit of electricity the panels generate. It doesn't matter whether I use that electricity or if it goes into the grid for others to use. Currently this is 48.84 pence. (I'm led to believe that new installations attract about 15 pence per unit.) Additionally, it is deemed that half of my units go into the grid and I receive an additional small payment for them, currently 3.44 pence. (Apparently it is about 1.5 pence for new installations.) These are index-linked to RPI and are tax-free. Over the six years, I have received £6,856 in FiT payments, which represents 48% of the original cost. That doesn't look as good as I had hoped. However, there is another aspect to this; I don't have to buy as much power as I would otherwise.

We're a relatively power-hungry household. Various set-top boxes stay on 24/7, we're fond of our tumble dryer and the kettle tends to be over-filled for the cuppas being made. Plus there is rather a lot of computer kit that is powered, much of it 24/7. So while the average UK household uses 9 units a day, we're a profigate bunch at 19 units a day! Happily, while light is shining on the panels, some of the house's power is being supplied by the Sun and I don't have to buy that power. If the available solar power is less that the house's consumption, then all of its output goes to the house. It is only when the house's needs are exceeded by the panels' output that power goes to the grid. Indeed, for much of the summer, the house spends hours totally powered by the Sun. Therefore, a substantial amount of our daytime consumption is free; we don't have to buy in that power. Unfortunately, I have no direct way to measure how much that is.

But as regular readers will know, I'm the type that keeps track of these things and I have enough data to take a decent stab at this. Across the last year before the panels were installed, our average daily consumption was 24 units. I know I can't account for how our pattern of consumption might have changed but it seems fair to suggest that, thanks to the panels, we are not having to purchase an average of 5 units a day.

Ignoring the standing daily charge, which we have to pay regardless, our current price per unit of electricity (one of the cheapest available - I've checked) is 11.76 pence. That makes 58.8 pence saving per day or £215 over a year. If that figure were valid for all six years, it would represent a total saving of £1,288 which, when added to the FiT payments so far, gives a total benefit from the panels of £8,144. This represents 57% of the initial outlay. That seems to be reasonably near to the 60% that would have matched expectation. Not bad for a set of panels that are far from being aligned due south. (Actually west-southwest.)

Solar Motion

Eight months ago, I leased an electric car which somewhat changes things. I figured that rather than sending power into the grid, I could use spare power to charge the car. Therefore, if I know the car could do with a top-up and I see that a sunny afternoon is generating lots of excess power, I'll run outside and get the car plugged in to mop it up. This not only saves me from having to buy that electricity had I plugged the car in at night, it also saves the cost of petrol that I would have had to buy to run my car for the miles that the car will do.

5,000 miles and an adventure

Eight months and 5,000 miles on and the electric adventure continues. I’m enjoying the ride even more than I expected. But let me state up front (and I'm probably repeating myself here) that given my circumstances, there is really only one significant drawback to the ownership of my particular electric car; range. Long distance travel is perfectly doable but requires thought and planning – more about that later. In other aspects, it's the perfect city runabout.

Running costs

A common question is how much is it costing to run? By that, people are asking what I am paying for the electricity that goes into it, and that's an impossible question to answer with any accuracy. There are a few ways for me to approach an answer and they all have reasons for being wrong. But by relating them all, I can probably give folk a handle on the money that goes through the charging port.

First is total consumption. Two weeks after I got the car, I signed up to Nissan's Carwings system. Through telematics, Nissan keep a log of the car's daily use and that information is available to me through their website. I harvest this data and keep it on a spreadsheet. According to their figures, they have totted up 4,241.8 miles using a total of 1,103.2 kilowatt-hours (or units) of electricity. This gives an average of 3.84 miles per unit, which isn't bad given that it covers the winter period.

Of more interest here is cost. Ignoring my daily standing charge, I pay £0.1176 per unit which implies a cost of £129.74. Had I done the same miles in my last, very frugal petrol car which averaged 10 pence per mile, the same distance would have cost me £424, a big win!

But wait, I didn't pay for all the electricity that went into the car. For example, we recently made a 600-mile round trip foray to Shropshire and the majority of the power used for that trip (about 170 units) was free from Ecotricity's Electric Highway network. Add to this the other times that I've taken advantage of other public chargers.

Additionally, except for deep winter, a fraction of the power that goes into the car comes from the solar panels on my house. In fact, if I know the car requires a top up and I see from my display in front of me that there is significant spare power available from the panels, then I'm outside in a flash, connecting car to house.

Is there another way for me to see how much more I've had to pay for electricity? Yes, because I'm a sad git who happily notes my electricity consumption each day, and have done for years. Therefore, I can compare the same 8-month period across 2014/2015 and 2015/2016.

As of writing, I've had to buy 469 more units of electricity (at 11.76 pence each) since I got the car compared to the same period a year before. That equates to £55.15. Unfortunately, that cannot be an accurate measure of the electric car's costs because it takes no account of other possible influences on our electricity consumption. Still, I'm not complaining. The truth lies somewhere between the two and I suspect it is a lot nearer the lower figure. Nearly 5,000 miles for the price of a largish tank of fossil fuel.

How poor is that car?

When I first got the car and was writing about it, I was aware that I might be seen to be overly biased in its favour. I tried to compensate by writing about those things I could find that could be criticised. Anything. It wasn’t easy, but I’ll try again.

First, a word about my expectations of a car. I have tended to eschew luxury motors and it is not my intention, even unconsciously, to use my car as a symbol of power and status. I know that to some extent, I’ve failed because by having two, albeit small cars in our driveway is, I’ve made a statement. Nevertheless, until I got my hybrid Yaris, the previous four Yaris cars I had were small vehicles with 1-litre 3-cylinder engines and entry-level equipment. I was perfectly happy with that. I'm not a connoisseur and my expectations are probably low. But when I stepped into the Nissan Leaf, it felt like an order of magnitude improvement in the levels of equipment and comfort that I was used to. I got another point of view from a BMW-driving friend who had a shot in the Leaf. He opined that it felt at least as smooth as his car. I feel it is an extremely pleasant, smooth, quiet, unfussy, responsive, calming driving experience and I’m very fond of it.

So what don’t I like? I don’t like the wipers. From new, they tended to streak and I’ve read that it is a good idea to replace them with some Bosch blades.

I don’t like the windscreen washers. Toyota had implemented great systems to minimise glass scratching by spraying screenwash in a powerful fan or delivering copious quantities direct to the blade. The Leaf’s skooshers are pathetic squirts in comparison, delivered from a relatively small screenwash tank. Nissan could learn a lot from Toyota.

I still haven’t quite got used to the relatively large pressure I have to apply to the indicator stalk if I want to give a flick indication. I like that even with a short operation of the stalk, the car continues to flash a few times. However, the force required to make it happen is nearly as large as the force needed to engage the indicator properly.

What else don’t I like. I don’t like that the music player doesn’t give a visual indication of the length of a track and its playing position. However, I have become used to the different sound quality of the system which bothered me at first. I had compared it unfavourably to the Yaris sound system.

I positively hate that every so often, and often at inappropriate times, a voice comes on and begins to tell me what my average energy consumption has been in miles per kilowatt-hour, what my ranking has been for efficiency in my region and to give me a tip for more efficient driving. I neither know how I turned it on in the first place nor how I can stop it from ever coming on again. It is very annoying, especially when it interrupts a good radio programme, causing me to miss a crucial section.

When there are three folk sitting in the back, they often complain about a large raised structure that gets in the way of the person seated centrally.

What else? Oh yes, the previously mentioned range. It would be nice if it had a few more miles, say, double? And I don’t particularly like the shape of the car. :-)

But in all honesty, I think it is a great car. It’s very well equipped. Far more knobs and whistles than I need or really want. Auto headlamps, auto wipers, rear camera, tyre pressure monitoring system, cruise control... drone on and on and on.

The bald truth is that I have to be really picky to find anything to moan about the car. I love its silence, its smoothness and its power. It is a good advertisement for what an electric vehicle can be and I really didn’t understand the car reviewer on a BBC Alba programme who took one for a review and didn’t like it. His frame of reference for what makes a car good is obviously radically different to mine. Maybe he misses the noise of a powerful engine massaging the seat of his pants or the whiff of hydrocarbon when it’s going in at the filling station, or coming out of an exhaust pipe. Maybe he had the car stuck on Eco mode the whole time.

Eco mode

When I first took delivery of the car, I was enthralled at the remarkable power it expressed when pulling away from a standing start. Whatever boy-racer tendencies I had as a twenty-something are long gone but for a while, now in my mid-fifties, I found the power, responsiveness and overall eager feel of the car quite exhilarating. On one occasion, I tried the eco mode and, ugh! Wet blanket. Back to the powerful ‘normal’ mode. And so it continued for a month or two until a conversation with somebody made me try it again.

Eco mode is now my usual mode of driving. It gives the car longer range around town because the acceleration is more muted. It lets me return to my more measured, typical-me-behind-the-wheel ecomiser personality. Now it is rather pleasurable when occasion demand that I be quick off the mark. I put a stop to the eco mode, hit the pedal and take off, whether it’s at lights that have caught me in the wrong lane or on a slip road onto the motorway, effortlessly syncing the car with left-lane traffic, something I had to do rather a lot recently during our trip south.

The Great Spring Electric Adventure

My better half was aware that I wanted to stretch the Leaf’s legs a bit so she suggested that we take it down to England to visit my sister in Shropshire, who is also interested in electric cars. And so it began; 296 miles – each way. The trip south would be split after 124 miles by a stay in Penrith, thanks to a late afternoon departure. With the planning precision of a military general, I plotted all the Ecotricity charging points along the way, noting the miles between each and drawing up separate lists for the southbound and northbound legs to take account of those sites that are only available in one direction.

With the spring weather getting warmer, I had been getting used to the range being around 90 miles and I harboured the idea that we might make Annandale (70 miles) but knew that Abington was available (46 miles) should we need it – and we did!

First, a little about range calculation. If I charge the car to 100%, I note its estimated range and zero the trip meter. Then as I drive, I watch the distance travelled increase while the remaining range decreases and I add the two. (I ignore the first mile of travel to give the estimate time to settle.)

If conditions are heavy or I’m pushing hard, the total drops. In good conditions or light driving, the total goes up. This way, not only do I see the available range, I monitor the total range to gauge overall performance.

As we climbed out of Glasgow into the Southern Uplands, a stiff headwind and heavy rain combined with the hills to dramatically reduce the total range down from 95 to only about 65. I set the cruise control to 60 mph and plugged away in the lorry lane. No way was I going to risk trying to reach Annandale. Abington would be our first stop and by the time we reached it, we had just 20 miles remaining – 69 total. It is possible that the subsequent downhills might have extended the range enough to reach Annandale 25 miles further on but I wasn’t here to exercise range anxiety.

A few miles short of Abington, still cruising at 60, we caught up with another Leaf whose driver was obviously eking out their power. Maybe they had their cruise control set at 57 or so. I thought to myself, if he’s just come through what I have, he’s probably short of power and has the same plan as me. I gingerly overtook him, still at 60, half expecting a race to commence to Abington Services.

Having pulled into Abington, we parked at the two pumps, both free, and as we gathered our things ready to plug in in the rain, the other Leaf pulled up. We settled down for a coffee and snack when the woman from the other Leaf approached us. Could I help them get the pump working?

Their story was that they own a Renault Zoe but were test driving the Leaf and were giving it a proper workout. They had come all the way from Inverness so had already dome 200 miles. Althought they had probably recharged twice if not three times in their trip, they were struggling with the CHAdeMO connector. They seemed to have got the sequence wrong and when I tried it, all came good. We would pass them again later.

At Abington we got back up to 92% charge but the range said 65 miles; not enough for Southwaite, the last stop before Penrith. I had expected 60 or 70-mile hops between charges but with the effects of the foul weather fresh in my mind, I chose to stop at Annandale for a top-up. And anyway, my better half wanted to get something from the shop there.

After another two dozen wet, windy miles, with our power still being hammered, we called into Annandale. There is only one ‘pump’ and two huge Mitsubishi SUVs were sat in both spaces next to it. I waited while the better half hit the shops. Happily, after only eight minutes, a space at the pump was free. It was getting dark and we knew this was going to take longer than planned. We were having to make more stops and I was reluctant to go faster. We elected to grab some fast food and let the car top up.

I decided to stop again at Southwaite, 40 miles later. Our hotel was 15 miles further but I wanted next day to start with a decent charge. On this occasion, I got a chance to learn the characteristics of rapid charging now that the rain was backing off a bit.

When first plugged in, a rapid charger delivers in excess of 100 amps, but as the battery heads past 90%, the current goes down to about 10A. This led me to think that it might be better to charge for a short time and do so more often. I could then go faster between stops rather than trying to make my power last.

Friends on Facebook laughed at how long it was taking us to get to Penrith. In the event, it was 4 hours to go 124 miles but it had been a stiff test. The heavy rain and high winds had cut my miles/kWh significantly.

Often when going up and down the M6, I’ve seen the signs for the Rheged Discovery Centre in Cumberland and wondered what it was. Since it was only a mile or two from the hotel and, more importantly, it has a rapid charger, we decided to start our day with a top up of leccy and a decent coffee. The centre turned out to be a lovely place. Fine coffee and great shops much admired by my better half.

Though we could have made Lancaster Forton Services (55 miles), and the weather was getting better, we were still affected by yesterday’s experience and had a top off at Killington Lakes (29 miles) and then headed on. We’d only stay at one place for 15-25 minutes then head off, setting the cruise control for 75 mph.

At Lancaster Forton Services, the better half headed to M&S to get sandwiches. Rather than eating mine now, my plan was to continue down to Charnock Richard Services and munch them during the next charge. This electric adventure was panning out reasonably well. The 'charge short and often' approach was working. I got to drive faster as I was less prone to wanting to eke out my charge. It was still wet but not as wild as before. At Charnock Richard Services, I went inside to get a takeaway latte and noted a bunch of old boys gathered around the charger inspecting its display.

Next stop was Knutsford, 29 miles beyond and a diversion from our original plan. Based on Google Maps’ suggestion, we had planned to take a westerly route past Chester and through Oswestry and around Shrewsbury. But just before our journey began, Ecotricity’s website had showed that two charger sites on that route were offline (Oswestry and Shrewsbury). Plan B was to stay on the M6 where there are lots of charging options and then past Telford on the M54.

The weather had cleared, there was about 65 miles indicated to our destination and the car was being bullish by suggesting a 90-plus mile range. We decided just to keep going to the end and see how the range would pan out. I mostly sat around 70 mph and was amazed to see how positively good weather affects the car's range. We made our destination without issue, taking a short cut suggested by the car’s satnav via Market Drayton.

This had been a slow but fun way to go 300 miles sans petrol. We felt that it was actually enjoyable to take more breaks in a trip. The car proved to be a pleasure to drive distance and I think that the cruise control is a real boon because it takes a level of mental activity away. I certainly felt more rested at the end of the journey than I would have expected had I been hammering down in long stretches. I think there is a cost for getting to a destination faster.

The trip south had given me insight to the charging characteristics and logistics of long journeys, and taught me to be aware of the effects that the weather or the topography could have on the journey. It was good to think about speed of driving versus charging time and how all these variables interact. Of course, when the 200-plus-mile cars become affordable, all this will become less of a consideration.

Heading home

First stop on the way up was Knutsford. Having fully charged at my sister’s place, we took a 70-mile cross-country route and had 22% remaining, a good result. With a good recharge, we could bypass Charnock Richard and so we pushed onto Lancaster Forton Services, about 54 miles distant, and we cruised at around 73mph. (I love cruise control.) There were 14 miles remaining when we got there.

At Lancaster, we had to decide; Do we stop at Tebay at 38 miles or head onto Southwaite, 65 miles distant? I was aware that Shap summit was ahead and took the sensible option, Tebay, which let me keep the speed up. Anyway, we were enjoying the relatively frequent breaks, even if they were less frequent than on the way south.

Tebay was reached in the blink of an eye. There were roadworks for the few miles leading to it and then I had one of those horrible moments when I thought I had screwed up. A slip road preceded the services and for a sinking moment, among the roadworks, I thought I had missed the turn off. Because I had kept my speed up, there were only 16 miles remaining in the battery and Southwaite was another 30 miles further on. It was an unpleasant, if short-lived thought and the services were a short distance beyond.

It’s a drag

Just as with conventional cars, a car’s speed affects its consumption in a way that has a nasty ‘square’ in the mathematics. But with a short-range car, you have to be more aware of it.

The drag felt by the car can be thought of as being due to all the little air molecules hitting the car and requiring a certain amount of energy to be pushed out of the way. That energy is the kinetic energy of the collision and a famous little equation lets us understand how it works:

Kinetic Energy = ½ mass times velocity squared

By this equation, if a certain amount of energy is required to push the air aside at 30 mph, then at 60 mph, the energy doesn’t just double, it quadruples! By hammering up the motorway at 75 to 80 mph to Tebay, I had shortened the range by quite a way.

At Tebay, we decided it was a good time to stop for a cuppa and give the car time to charge. It was hard to find the chargers as they were poorly signposted and tucked away at the far end of the complex up to the left. As we crawled around the car park looking for them, I had another 'oh no' moment. When we located them, we found charger to be off. Happily, the other one was good.

Out of the way charging at Tebay.

We returned to the car after 45 minutes to find the charge had stopped. Had it stopped prematurely? I was glad to see the car report a 93% charged battery and I don’t know if there was a time limit set on the charger. At any rate, it had charged well. Annandale was my target at 69 miles (with Southwaite and Gretna as alternatives). It should be the last stop before home.

When travelling southbound on the Spring Electric Adventure three days ago, our initial reticence combined with the heavy weather made us top up the battery every 30ish miles. The return journey was proving to be very different.

After Tebay, there was a little concern as the road kept climbing up to Shap summit and the range promptly shortened. Then as we descended, it lengthened again as we sailed past Southwaite and Gretna. The numbers indicated that we should make Annandale with about 10 miles remaining after 68 miles. The actual number remaining was nine miles, a bit close for my better half’s comfort.

Having just done 68 miles, the 69 miles to home seemed readily achievable. The only obstacle would be Beattock summit. Yet I knew that if getting up there took too much out of the battery, we would have Abington and Hamilton as alternates.

As we headed to climb to Beattock summit, I thought, sod it, I'll keep the speed up and do a quick 10-minute top-up at Abington. Rather than going slow, I can sit at 75 (indicated - about 70 true) for the downhill to Glasgow. Then I note that the driving and charging has caused the temperature of the battery to rise to the highest I've seen it.

Battery temperature

The left side of my main display has a large fan-shaped temperature display. The top two segments (10 and 11) are indicated in red and the car was indicating the ninth segment. I normally see it at 4 or 5. This is unexpected and I wasn’t sure whether it would be a problem.

The Leaf is unique among battery EVs by not having an active thermal management system for the battery, relying instead on forced airflow. This saves weight and complexity (and cost) but Leaf owners in hot countries and states have reported problems. It seems that as long as the gauge doesn't go into the red, I can continue what I'm doing. If it does go into the red, I'm not supposed to rapid charge the battery.

I assume the temperature shot up because of the rapid charge/discharge that I was doing by going 300 miles in a day and cruising at 75mph. Outside temperature was only 10°C. It bothered me when I first saw it, not knowing if it was a trend that would put the trip's progress into the slow lane. In the event, it sat one notch below red for the final charge and the last 100+ miles.

At Abington, my intended 10 minute stop stretched a bit as a couple of older guys from Wales quizzed me about electric driving. It is fun to see preconceptions fall away as they learn a little about it all. They looked at the car and found it to be larger than they had imagined. They realise it's just a car. They ask about the cost of the electricity I'm pumping in from the Ecotricity charger. Their eyes widen when I say zero. Folk really dig it.

We get home about 9.5 hours after leaving. It wasn’t the fastest way to go the distance but it was relaxed and enjoyable. I would happily do it again, wiser, and perhaps with a Tesla.

Tesla Model 3

An early impression of the Tesla Model 3.

Just before we headed south, Elon Musk announced the Tesla Model 3. I’ve been anticipating this for a long time, having had the pleasure of driving a Tesla Model S in 2014. I completely buy into what Tesla is trying to do. I think they are a necessary disruptive force on an motor industry that was finding it difficult to work outside accepted norms.

I therefore became one of the 400,000 folk who have put our money down with a refundable deposit for one of the new cars. It is a worthwhile statement of my intentions and it helps indicate to the company that they should push forward with mass sales of (relatively) affordable electric cars.

If I do eventually decide to turn my reservation into a car sale, it won’t happen for at least two years. Model 3 production is set to begin late 2017 (if all goes well). West coast USA will be served first and it will be a while beyond that before right-hand-drive cars. But the car looks amazing and, although a bit of a swish car for me, will probably be a worthwhile long-term purchase.

Exciting times.

Gimme back my Leaf!

Today, 8 January, was as cold as you would expect Glasgow to be this time of year. However, for this winter, it was uncharacteristically cold as we've had exceptionally mild temperatures thus far. Consequently, there have not been too many days when I can get to grips with charging the Leaf in cold weather. Today was one that tested the system.

The Leaf had been left plugged in for a couple of days as I hadn't got around to unplugging it. During that time, there had been some rain. When I looked out this morning, there was a picturesque coating of frost on everything. It wasn't deeply cold but skies had evidently cleared and the temperature had headed below freezing point.

By lunchtime, we had decided to go out for food so it was suggested I get the car warmed up. I prodded the app on my phone to switch on the climate control from within the house. Within 20 seconds the blue light in the car was flashing to show it was heating up. Within 4 minutes, the frost on the windscreen had liquefied and a dry patch was forming. By 10 minutes, the warm air on the inside had heated the windows sufficiently to defrost all of them.

We headed out of the house and locked up. "Hop in quick," I suggested to my wife, wanting to keep as much of the warm air in the car as I could. Meanwhile I went to the car's nose to remove the charging cable. The normal sequence is to press a button on the top which is one end of a plastic lever, the other end of which is a latch to hold the plug firmly in its socket. I then pull it out. The button also tells the car that it is being unplugged which stops any charging that might be happening. If the remotely-switched heating is on, the button also causes it to stop.

I pressed the button and immediately felt a resistance to its movement. The plug would not unlatch and repeated attempts were to no avail. I figured the rain over the last couple of days had got into the plastic lever mechanism and had iced up. The Leaf was going nowhere.

We made our journey in my wife's car and returned an hour later. Being the middle of the afternoon, most of the frost on the cars had melted so I had another go. I felt a slight crunchiness as the button depressed. I had crushed what remained of the ice inside the lever mechanism and I was rewarded with the plug coming cleanly away in my hand. I wouldn't have to phone the Nissan breakdown service after all.

My lesson is to try and avoid leaving the car plugged in for long periods where rain might ingress the plug's latch mechanism and then ice up. On the other hand, I can easily imagine a situation where the car gets plugged in overnight, then there is a rain shower followed by clear skies before dawn which freeze everything solid. Were I able to park the car under a overhang or in a car port, this wouldn't be a problem as it would be kept dry. But I can't and so the plug and socket are exposed to the elements.

Strictly speaking, the flaw is in the design of the plug and is nothing to do with the car itself. It's just something I'll have to be aware of.

The cost of power

A few days ago, a friend asked me if I knew how much I had spent on electricity to run the car. Interesting question and quite hard to answer. The Nissan website tells me how many units of electricity I have used each day and I cold add that up. Also, I believe that Chargemaster, who installed my outdoors charger, could tell me how many units have passed through that unit, but I have yet to subscribe to that service. The problem with either of these is that while there is significant sunshine, a decent fraction of the car's power comes from my solar panels and thus, I don't pay for that. But there's nothing to tell me what fraction came from the panels.

I do, however, have an interesting graph. Because I keep a note of my retail electricity meter, I can compare last year's purchase with this year's. Here's a graph that shows the cumulative difference between the two.

For the first 40-odd days, we were purchasing no more electricity than we did last year. Then for the next 20 days, we were actually purchasing substantially less electricity than last year, which I conclude was due to the very sunny October we had. The little upward tick around day 77 to 79 was when I was getting charge from a Glasgow car park every day and around that time, I made a trip to England with a diesel car loaned to me by Nissan. What this shows is that for the first 80 days of ownership, despite running the car, we bought no more electricity than we had a year ago.

As we plunged into a very dark, wet November and December, the situation changed and the graph takes a nosedive. What's then interesting to see is that for the past 20 days, it has levelled out again.

As of today, over the time I've had the car, we have bought 279 units more than we had last year. That's all the graph says. I can't define exactly what part of that was caused by the car. Ignoring the daily standing charge (which I would have had to spend anyway), my cost per kilowatt-hour is 11.76 pence. Having had the car for nearly 5 months and done over 2,500 miles, I've had to buy £32.81 more electricity this year than I did last year. If I had made more of an effort to get power at public chargers (most of which are free), it would have been even better. Fascinating!

Coming up on 2,000 miles

It is three and a half months since I took delivery of my Nissan Leaf and I'm heading towards 2,000 miles on the odometer. It is about time I wrote down my impressions based on months rather than days of use. So here goes.

For me, there has been one, and only one drawback to owning an electric car. You guessed it. Range. Let's get that out of the way for starters. I'm in the lucky position that we have two cars in the household and if necessary, I can use my wife's Aygo for long trips. If we didn't have that, it would be a significant problem. So what is the useful range turning out to be? I'd say that if a destination is more than 35 miles away, then I would need to think carefully about my options.

I wrote in an earlier post about driving to Bathgate (33 miles) and being left with about 16 miles indicated range by the time I got home. That was in summery weather. I did another trip in roughly the same direction when asked to give a talk at Forth, a village 33.5 miles away high up on the moors between Glasgow and Edinburgh. 

Before the trip out, I topped the battery to 100 per cent and we left well wrapped up, choosing not to use the heater heavily - just enough to keep the windscreen clear. It was a wild night. Mild temperatures but heavy rain blowing in from the south. As we climbed from the M8 motorway into the Lanarkshire hills, we were driving into the wind and I watched the instruments as the battery's charge smartly headed towards 50 per cent. There was nowhere at the destination to easily get a charge and there wasn't time to set anything up, even from a domestic socket. We were busy enough trying to get props and books in through the rain and gales.

The one thought that told me it would be nothing to worry about was that, having come uphill, we would be going downhill on the way home. Additionally, having driven into the wind, we would have the gales behind us on the return journey. So it turned out. We took the battery to 54 per cent on the way there. The journey home took us to 15 percent and by the time we were hitting the Glasgow outskirts, I knew we were home and dry so chose to luxuriate in a bit of heat. I'd used the climate control for most of the journey because the humidity demanded a flow of air over the windscreen but I had kept the temperature at 20C and set a slow fan speed. Now, with energy to spare, we could raise the temperature and enjoy the last ten miles in warmth. A great night and an enjoyable drive in hard weather. But I wouldn't have liked to have had to travel much further.

There were contingencies. There is a rapid charger at Hamilton Services on the M74 that we could have diverted to and another at Whitburn, further out from Glasgow. Twenty minutes on either would have given us a buffer, should I have found myself short of charge, but it illustrated a continuing infrastructure shortcomings.

Despite Ecotricity having the Electric Highway rapid chargers along nearly all of Britain's motorways, an important service station they have yet to cover is the Harthill Services between Glasgow and Edinburgh. Another invitation for a talk illustrated this when I was asked to go through to the capital. At 48 miles distant, Edinburgh is firmly outside the radius I could do on a single charge. Plugging in along the way is a necessity if I am to use the Leaf for such a trip. Had there been a rapid charger at Harthill, it would have been straightforward. As it was, my wife kindly lent me her car for the trip.

I was also surprised to note that Edinburgh is very poorly served by chargers, especially when compared to Glasgow. A week spent working in Glasgow city centre illustrated how good Scotland's largest city has become for electric car drivers. Parking in Glasgow centre is expensive, like most big cities, and I took the train in for the first of five days. I knew there were charge points in the big multistorey carparks but I didn't know how the system worked.

It so happened that my wife came in that first evening to meet me and she parked in the Cambridge Street Carpark, only a few hundred metres away from where I was working. After dinner and before we returned to her car, we asked in the carpark office how parking worked for electric cars. Simple. Drive in and get a ticket as normal. Park at one of eight chargers and get plugged in. They use the 'Charge Your Car' network for which I have a smartcard and the power is free. I should then go to the office and sign in (name, date, car registration, time in, time out) and they would give me a second card. This second card would clear the parking cost indicated by the first card.

The next day, I drove in, plugged in, signed in and went off to work clutching two cards for the carpark. Over ten hours later, having put in a solid, busy shift, I returned to the carpark and put my main ticket into the pay machine: £24.50. Ouch! I put the second card in: £0.00. I must admit there was a bit of a grin on my face as I got to my car and unplugged. Thirty minutes earlier, I had used my phone to switch on the climate control so the car was not only dry but also cosy and warm, as well as having a topped-off battery. This went on for the rest of the week and there was never any problem getting a space.

I know I'm a bit of an evangelist about electric cars so I try to only talk about them when people actually ask. However, it is a distinct pleasure taking someone for a spin and watch their preconceptions about electric cars get left behind as the vehicle smartly takes off out of a junction. This is especially so because of people's expectations of me as a driver. I'm seen as a slow, cautious ecomiser with a light right foot, constantly trying to stretch my miles per gallon figure. Therefore the last thing they expect is when I take off like a thoroughbred fighter jet on afterburner and no gear shifting. In these scenarios, the only things shifting are paradigms in people's minds.

I had another long distance journey to make in the last few weeks as I wanted to travel to Pontefract to see a lecture by the great Jim Lovell, the commander of Apollo 13. As a purchaser of a new Nissan Leaf, I had read that Nissan will offer a loan of a long-range car for up to two weeks once each year. It was time to test this. Nissan customer services referred me to the dealer who could not have been nicer. They offered me a Nissan Pulsar demonstrator; diesel-powered and with even more fancy knobs and whistles than the Leaf (and that's saying something). I returned the Pulsar three days later with only two complaints about it: it had a gearstick and it had an internal combustion engine.

The driving experience in the Leaf is still enjoyable. The unfussy, easy but powerful acceleration doesn't get old. All four of us were returning from a restaurant and I took us up the nearby Boclair Hill, a 12 per cent gradient coming from a set of traffic lights that normally has all but the largest ICE powerplants roaring to provide the power to get up from the standing start. I floored the Leaf's accelerator and as we quietly reached the top close on an indicated speed of 50mph, my son commented, "So, what's a hill?" It was like it wasn't there. I wonder what it will be like if I ever get a Tesla.

Running costs are paltry. Our electricity bill will doubtless rise as I'm starting to see the effect of the occasional charging on the house's consumption. But as best as I can tell, and ignoring any electricity acquired for free out and about, fuel costs are roughly one quarter of what I would expect for an efficient ICE car. I've really stopped worrying about it. In addition, with only one moving part to the motor, servicing costs are likely to be minimal with brakes, tyres, wipers being the chief concern at the one-year service. I'll report on that when it happens.

Given our increasing awareness as a civilisation of the damage we do by putting carbon into the atmosphere, it is incumbent upon us to remove ourselves from our reliance on fossil fuel. My Leaf not only allows me to do my bit towards that goal, I'd argue that it has raised my standard of living in the process. Watching gases come out of the tailpipes of other vehicles seems just so anachronistic, so last century, and we're expected to breathe that stuff along with our life-giving oxygen.

I accept that a fraction of the electricity I use was derived from the burning of fossil fuel, but here in Scotland, that is a fast-declining method of generation as well as being a more efficient means of converting carbon to energy. Nuclear, wind, hydro and solar, all near-zero carbon sources, dominate the electricity industry here. If the Sun is shining, my own solar panels can put photon-derived energy into my car. This is a cleaner, quieter, more civilised means of personal transportation and I thoroughly recommend it.