Turning a new Leaf

Alternative energy has always fascinated me, as long as it is practicable. The solar panels I installed in 2010 were an expression of that but I've been equally interested in the idea of ditching fossil fuel as a means of powering a car.

Ever since I bought my first car in 1983, I've kept meticulous notes of all the fuel that's been hosed into my various cars over the years. Thanks to that and the recent use of consumption meters even in small cars, I've become very aware of the driving techniques that can drastically improve a car's mileage; steady cruising slightly below typical speeds, mild acceleration and anticipation of slowing or stopping to avoid the unnecessary use of brakes.

Since 2003, my car of choice has been the Toyota Yaris. It combines a relatively frugal consumption with half decent levels of trim. My most recent purchase of a Yaris Hybrid took this drive for efficiency one step forward. The main advantage of a hybrid car is that a battery and electric motor can take up the drive at those times when the internal combustion engine would otherwise return just awful mileage. This includes most city driving like sitting at lights or moving slowly. Comparing typical summer consumption figures of a 1-litre Yaris to a 1.5-litre Yaris Hybrid, I saw a jump from 55mpg to 65mpg.

I would note, however, that in the real world, Toyota's claimed consumption figure for the Yaris Hybrid of 80mpg+ is frankly unattainable across a full tankful of petrol. This from a driver who could just about achieve the manufacturer's numbers in a conventional car.

Ultimately, the hybrid car is only a halfway house. All of its energy comes from petrol. However, one thing I really gleaned from it was a sense of what driving an all-electric vehicle would be like. The drive train is so well designed that you hardly notice the change from electric to petrol. It's very smooth and very impressive.

A couple of years ago, I spotted mention of the Tesla Model S. Quite simply, this is an astounding car. While it's definitely out of my league (it's meant to turn wealthy petrolheads into leccy-lovers) it is nevertheless a game changer in the world of motoring. I place it as being perhaps the most influential, disruptive car of the last century. I had a shot in a Tesla about a year ago. Smooth, fast and responsive, it was an utter delight to drive and it most definitely points the way for the future. This is how cars should be. Ditch that engine!

Another important car in the electric vehicle field is the poorly named 'Leaf' from Nissan. First brought out in 2010, it has had five years of refinement but at first view, it is very expensive for someone like me. Nissan brochures show it as costing between £16,490 and £25,590 and the cheaper end of that range doesn't include having to hire a battery pack for at least £80 per month. This is way out of my range.

One option that excited me was to go for a second hand Leaf. I saw a video by Red Dwarf's Robert Llewellyn about how Orkney, a place I love, has become self-sufficient in electricity generation. The farmers there are busy putting up wind turbines and buying Leafs from a guy who trades in new and second hand electric cars. They get to drive around for next to nothing, and meanwhile, Orkney is wondering what to so with all the spare leccy being generated.

I decided that there's nothing to stop me having a test drive. I researched nearby Nissan dealers and headed off for a look. Macklin Motors is not far from me. Unlike the swish glass palaces that typify an Arnold Clark showroom, Macklin's was little more than a white-painted industrial unit. Two second hand Leafs sat on the forecourt and the salesman, apparently their electric car specialist, took the two of us for a spin.

Loved it! The Leaf is no Tesla, but it is nevertheless a smooth, quick and impressive car. Still, it was not my intention to buy one at that point. At the end, I thanked the salesman and said I would think about it. He looked so deflated, poor soul. I did think it odd that he claimed never to have heard of Tesla when I mentioned it. I'd have expected he'd be all too aware of the coming competition, especially since their direct-to-public sales model threatens his job in the long term.

I then looked more closely at Macklin's website. The offers they had for the Leaf were strange. Some were incredibly good yet, quite frankly, they were inconsistent with others. Some deals had a low-spec vehicle costing a lot while for others, high-spec cars were astonishingly accessible. It appeared that a mistake had been made on the site. The thing to be aware of is that the sales model makes it mandatory that the car's battery pack be hired to the customer. The low end for this is £80 per month.

I decided to pursue this further. One apparent deal would cost me £50 less per month than my Yaris Hybrid was costing me and there ought to be a further £50 per month saving on petrol. This for a car that was in the middle of the Leaf range. Importantly, the small print said that the price included battery hire.

I toddled back to Macklin's to the surprise of the salesman. He later told me he had thought I didn't like the car. In truth, I had chosen to be inscrutable. I said I was interested in their web deal for the Leaf Acenta. "The £200 per month deal?" he asked. I told him that there was a much cheaper deal and we both looked on the website. "That must be a mistake," he said as he scrutinised the small print. I pointed out that as I understood it, I was within my rights to take advantage of it and he agreed.

So my new Leaf was ordered there and then. It'll be red to keep the cost down (no metallic paint charges), cheap as chips to run and a 2-year experiment in owning and running a leccy car. I've got it on a PCP deal so I'll hand the car back at the end and walk away. Nissan are adding a healthy contribution, the balloon price is large (which makes the monthly payments small), the government are contributing to encourage electric cars and I will add a small deposit. Oh, and it's zero percent interest. It arrives at Macklin while we are on holiday so we'll wait until we get back to take delivery of it. Anyway, we need the Yaris for our trip up north.

And there's a thing. Range is going to be an issue with a car that goes for 90 miles at most before needing a recharge. To counter this, I'm told that Nissan has an arrangement whereby I can borrow a petrol car for up to two weeks per year to cope with longer trips. I have two upcoming short drives to England coming up where I get to test this offer. I think it's a good time to try this out.

A charger is on order from Chargemaster. The UK government are subsidising this by 80% and the remainder, a couple of hundred, will apparently be covered by the Scottish Government. I pay nowt. I've signed up to Ecotricity's Electric Highway which offers rapid charging and it free. I've also bought a £20 swipe card that lets me access the Charge Your Car network and it's usually free. It feels like the system is bending over backwards to get folk to go electric. Okay, I'll bite!

Five years and counting

Across five years of operation, I've never tired of gathering readings from my solar panels and watching the daily variations in power generation. The long term changes are as fascinating as those that occur across days or weeks. I now grasp in a way that I never had before why nature shuts down in winter. Though the eye perceives daylight in mid-winter when the Sun sits low in the sky, there really is very little energy remaining for plant life to photosynthesise. An overcast day in January can yield so little power that the power meter doesn't even register a tenth of a unit and remains at the same figure as the previous day.

So I have had these panels for five years. Here are the results thus far. First, how this last year compares to the first four:

2010 to 2011 - 2613.7 kWh
2011 to 2012 - 2398.0 kWh
2012 to 2013 - 2414.2 kWh
2013 to 2014 - 2433.4 kWh
2014 to 2015 - 2573.9 kWh

Second best year thus far, and higher than my original estimate of 2,500 annually. However, the average over the five years is a little low. I certainly don't get a sense of a slow decrease in the panels' efficiency. There's too much variability in the totals to perceive that. Here's how each year rose to its final value:

One interesting point to make is that we had a very sunny April this year. As a result, this year's generation had actually overtaken the first year on a single day less than a month ago before the high pressure system collapsed and the rain returned. Also, with just a week to go before the fifth anniversary was reached, the system appeared to have died. Except for the fact that the Sunny Boy inverter is guaranteed for five years, I felt a pit in the stomach. In the event, I need not have worried. The generation meter was also dead, a sure sign that the system wasn't receiving mains power. It needs a feed of mains to know how to synchronise the alternating current it generates with the grid cycles. In the event, I located a circuit breaker in the mains feed to the inverter and found that it had tripped. At this moment, it was a sunny day and the panels were surely generating significant power. I took the precaution of phoning the engineers at the installation company and checking there was no reason not to reset the breaker before doing so. All is well.

This graph shows the daily generation over these first five years:

As if I need proof, it shows just how variable Scotland's weather is, yet how consistently variable it is from one year to the next.

An important question is whether the finances of the system are performing as expected. At the start, I had estimated that it would take ten years to pay for itself. After five years, I would hope to be halfway to that goal, and so it seems. The installation cost me £14,300. Payments from the Feed-in Tariff (FiT) system has brought in £5,600 so far and I reckon to save a further £300 annually in power that does not have to be purchased - about £1,500 thus far. That makes a shade over £7k. Since the FiT payments rise with the retail prices index and the cost of electricity is set only to rise, I'd expect gains from the next five years will be more than equal. My ten-year target seems spot on. Everything beyond that is pure gain.

Year three's ups and downs

I'm astonished that the third year of solar generation has been completed. I have another fistful of numbers with which to contemplate and compare the generation of electrical power in cloudy West Central Scotland. I'm really pleased to have continued logging my power generation faithfully for over a thousand days and I've no thought of stopping. It's too interesting. So how was 2013/13?

Well, it was almost exactly the same as the year before, beating it by a mere 16.2 units at 2,414.2 kilowatt-hours of electricity generated. Compare this with year 1 which was better by nearly 200 units. Also compare it with the predicted generation figure, 2,480 units, that was given to me by the Installation Company. Actually, if you average across the three years, actual generation has been almost identical to the predicted value.

A favourite method I have of visualising and comparing each year is to graph out the accumulated generation:

You can see how a 200-unit offset between the first (blue line) and subsequent years really came about thanks to a good autumn that we must have had in 2010 (or maybe two rotten autumns in 2011 and 2012). Year 3 is indicated by the yellow curve and you can see that towards the latter part of the year, a sunny April was beginning to close the gap on year 1. Then there's a sudden kink that takes the line back towards that for year 2. This kink coincides with 2 May 2013, which just happened to be the day my son, Kevin, had chosen to begin a bid to climb all of Scotland's Munros in 100 days. (There are 282 Munros, Scottish mountains over 3,000 feet height so it is a considerable challenge.) He immediately got hammered by wind, rain, hail and snow; and my panels suddenly saw little light.

A new green-coloured line that represents year 4 is beginning to show on the left but it's too early to determine any trend. However, one week into the year, the panels recorded their highest ever single day's generation figure of 22.4 kWh and we're still a month away from the summer solstice. The next nearest figure came on 17 June 2010 when the panels were a month old and that was only a few days from midsummer. This gives me reason to believe that the panels are showing few signs of deterioration.

In summary, the panels are doing exactly what was expected of them and I'm very happy and settled with the return thus far. What is interesting to see is that having a set of panels adorning the roof is no longer unusual. I see them all the time now. Despite the huge fall in payments for generation, interest is obviously still high, helped no doubt by the rising price for retail electricity and the plummeting cost of panel installation.

On another connected note, my liking for environmental toys has been tickled by the purchase of a hybrid car; a Toyota Yaris T4 Hybrid. As I have always done, every drop of fuel that goes into the tank and every mile travelled with be dutifully logged and entered into a spreadsheet to see if real figures match my expectations and the manufacturer's claims.

Catch up the numbers

Okay, so the blogging idea kinda fell away somewhat. I did have a little bit of an excuse because, out of nowhere, an idea came to me to write a Haynes Manual about the Apollo Lunar Rover. Thanks to linking up with Christopher Riley (@alifeofriley) and Phil Dolling, the book has been published. But a desire on the part of Haynes to have it available for Christmas meant that the second anniversary of the solar panels coincided with an intense period of writing and editing activity. Now that our book is out there and living a life of its own, I've got a chance to catch up with the progress of the panels and their generation.

Year 2 had a good start with a few sunny days, but within a week, it had fallen behind year 1. This was about the time we had an unseasonable storm blow through and it did so with the trees in full leaf. As a result, Scotland's summer of 2011 looked rather autumnal with the windward sides of many trees covered in brown leaves. It was also a notoriously bad summer. Nevertheless, by the end of July 2011, year 2 had nearly caught up on year 1. Autumn 2011 was a really poor one with a second storm blowing through and by December 2011, year 2 was 200 units behind the first year.

By the second anniversary, year 2 had generated 2,406 units which is a little down on the 2,480 suggested by the installation company and 207 below last year's total. Here's a diagram that compares each year by graphing the cumulative generation. It includes the first half of year 3.

Mid way through year 2, the difference in generation between the two years did make me stop and wonder whether the reduction was due to some sort of drop in efficiency. However, I don't think this is the problem. Notice how, having achieved a 200-unit separation, the two graphs more or less keep that separation. Also, year 3 is managing to keep up with year 2 and because of recent good weather, has surpassed it.

In truth, solar panel generation in Scotland is extremely sensitive to the vagaries of our weather. A hot spell like we used to get in times past could transform a year's generation figures. And it is true that both of the last two summers have been rather poor. Here's the overall graph of daily generation since the panels were installed.

In a previous post, I speculated that the distinctive dipping at the top of the curve might be due to the summer Sun setting behind a stand of trees to our northwest, essentially capping the curve. A friend who also installed panels (which favour the easterly, morning Sun) suggested that what it shows might actually be evidence of the jet stream passing over Scotland. Supporting his assertion, he showed me his version of my generation graph above, including a 30-day average. Lo and behold, there was a very similar midsummer dip.

Cloudy days and Sunspots

I had a chuckle the other day when my son opined that it had been a really dismal summer. "Yeah," I said, "the units from the panels are way down on last year."

"Typical," he laughed. "It's funny how, for me, it's just a feeling and you have the figures to back it up!"

My obsession with logging things on spreadsheets is becoming legendary and, right enough, our poor summer has been reflected in an increasing difference in the generation from the panels between the first and second year of operation. This first graph illustrates the difference between the two summers.

It started well but we did have a ridiculously awful late May and June. We even had a storm that would not have been out of place in the middle of January. A lovely spell in July meant that this summer almost caught up with last, but since August and right through autumn, there has been no shortage of cloud over west central Scotland and the declining orange line on the graph shows the result in my generation.

As of today, the second year of the panels' operation has yielded 170 fewer units of power compared to last year which represents an income drop of about £73. So are there any reasons why this summer has been so bad?

It is next to impossible to treat a single summer as a statistically valid data point so I'll throw a health warning over the following but it does seem that, over the short term at least, the Sun's variability has an effect on the weather in the northern hemisphere.

Now, of course, the Sun's output is the basic energy source for all weather on Earth but scientists were loathed to make a connection between the slight variability we see on our local star with more profound changes in weather, despite a number of interesting coincidences. For example, many of our recent hot summers in the UK do coincide with the peak of the Sun's sunspot cycle. In 2003, we were soaking up the Sun in Kirkwall on the Orkney Isles when they had their hottest day ever recorded at 26 degrees. (Orkney is quite far north and surrounded by sea which means that although it can be a wild and stormy place, it never really experiences extreme temperature changes.) At the same time, the heatwave caused the deaths of many old folk in France which became a national issue for them.

My mum tells me that the summer I was born (1959) was a very hot one and she was glad to get me out. The following graph, which shows monthly sunspot numbers, indicates that for both these years, the Sun was at the maximum part of its 11-year sunspot cycle.

However, a counter to that is the summer of 1976 which was very long and very sunny yet which coincides with the sunspot cycle being at its minimum. Yet it has long been noticed that major periods of low sunspot activity coincide with depressed temperatures in the northern hemisphere. The most notable of these is a period in the late 17th century called the Maunder Minimum which also saw normally ice-free rivers becoming fully frozen on regular occasions. A smaller dip around 1800 also seemed to be associated with famously cold winters.

Now new research by the Met Office and others based on measurements from NASA's SORCE satellite begins to hint at a possible mechanism for these coincidences. From this BBC article, it seems that the Sun's UV output is much more variable than previously thought. Its effect on the atmosphere is theorised to affect our jetstream, the high-speed airflow that dictates the run of low-pressure systems that feed up the Atlantic Ocean towards the UK

Essentially, the quality of the Scottish summer is dramatically affected by how far south the jetstream runs and it seems that the absorption of energy from UV sunlight may be a major factor in that. If the jetstream is north of the UK, we sit in the same high pressure system that dominates the weather of southern Europe and we get more sunlight. If the jetstream comes south, it brings with it the frontal systems that mean cloud and rain.

The research is mostly concerned with how cold our winters get and it suggests they may be milder over the next few years as the Sun's cycle builds to a peak. Right enough, we've just had two very cold winters and they coincide with the longest period of no sunspots for a couple of hundred years. If so, I might have fewer days when snow on the panels blocks their ability to generate anything. I'd like to think that in the near future, there might be a summer to compare with those of years gone by. That is something that would transform the return from the panels.

Back to the generation graphs.

This graph represents my generation since installation and the patterns are becoming clearer. Of note is the truncated summer peak. As the Sun gains altitude towards midsummer, one would expect the average figure to display a rounded curve that is roughly the inverse of the winter dip. instead, for both summers, there is a pronounced clipping of the curve. My favoured explanation for this is the tall trees to the northwest of the house. As the setting Sun of summer goes towards the northwest, it begins to hit these large trees which cut off the last hour or so of sunlight.

Another figure of note from the spreadsheet is the average generation across the year. It stands at 6.69 units per day, slightly below the 6.79 figure that had been my original target and it represents 2,441 units over the last year. Given that I am 170 units down over the summer, this low figure is hardly surprising. Let's see what the winter brings.

A Feast of Figures

At last, it's one year on for my solar panel installation and time to give an overview of its operation. When I was given a quote for the work, Installation Company told me I should expect 2,480 units annually. The actual number was 2,613, a decent amount, given that my system is not ideally aligned. The panels are on a 30-degree roof pitch that faces WSW. I think performance has been good knowing that Glasgow is not a part of the world known for sunshine. Anyone who is more southerly aligned than I am is going to do substantially better.

Not all of those 2,613 units attracted the Feed-in Tariff (FiT) payments. I lost a week's worth at the start while the bureaucracy surrounding FiT application worked it's way through. Nevertheless, the FIT's earnings for the year have been about £1,044. I say 'about' for two reasons. Half of my eligible units, 1,250 of them attracted an additional Export Tariff of 3 pence which adds £37. Also, both the Export Tariff and the FiT were increased by the inflation rate on 1 April. However, the people looking after the payments have no way of knowing what my reading was on that day so I guess they will apply the higher rate for my next reading which means that a few units from before April will attract the higher rate. Note that not only are these payments index-linked, they are also tax exempt.

Average generation per day was 7.16 units across the course of the year, pleasantly clear of the 6.79 target I was hoping to exceed.

The year prior to the panels, we used 8,816 units of electricity in our house - sons have a habit of leaving their stuff powered up! This year, primarily due to the power provided by the panels, our consumption has fallen by 2,180 units to 6,636 units which represents a saving of about £220 pounds at current rates. Adding that to the income above, we ought to have realised £1,300 by virtue of having the panels. Three major factors will affect that in future years. The price of retail electricity is bound to rise, increasing the savings that can be made by using power when the panels make it available; for example, coaxing the family to run items like the dishwasher when the Sun is out. The FiT payments will rise along with the Retail Prices Index. The panels are expected to deteriorate at about 0.9 per cent annually.

Now for the big, important chart from my spreadsheet:


When I first started this, I tried to guess what shape this graph would have. I thought that mid-winter would still yield a couple of units daily. The effect of weeks of snow on the panels was not expected, essentially turning them off for days on end. I suppose I expected an approximation to a sinusoid waveform but I now think that, over and above the snow, the alignment of my roof amplifies the effect of the lowering of the Sun's passage over the sky. Now I really understand why life goes to sleep over the winter. The prime source of energy for life, the Sun, basically all but disappears.

For the future, I am going to keep track of my panels' performance. My overall average figure will now become an annual average. A new figure I will be generating is a comparison of current generation with the previous year with a running total of whether I've generated more or less this year. Everything else being the same, I should see a very slight decline. However, given the variability of the Scottish cloud cover and a good summer, figures could easily be higher.

Nearly there

The Sun is out in west Scotland with a vengeance and the units are clocking up with gusto. It's been gladdening to see generation return to high levels and there ought to be no impediment to exceeding my target amount. With the current sunny weather, the panels have been achieving over 19 units a day.

A week ago, I had a visit from the chap who installed the system. I pointed out a long flow of bird pooh that had run halfway down one of the panels and up he went to clean it off. Apparently, tests done by his colleagues showed that even small areas of shading have a profound effect on the entire string of cells. Since they are connected in series, the shaded cell acts like a resistor and impedes the flow of power. He gave the panels a quick once-over while he was up.

Now to the figures.

My annual average is 7.02 units, having passed the 6.79 figure required to hit target a week ago. 30-day average is a healthy 12.19 units. Here's the graph that covers the life of the panels.

To see better the recent improvements, here's the last two months. Remember, red is the 30-day average and yellow is the overall average.

I'll report on the first year's generation in two weeks time.