Week two update

It's a little later writing this than I intended as pesky brother-in-law (   ;-)   ) decided to phone and tell me how his system was operating. He was also asking if my large spreadsheet for entering power data into could be passed onto another person who generates solar power. No problem. One of the points we discussed was that it would be a good idea for Installation Company to ease their customers into the Feed-in Tariff by providing at least a checklist of the hoops they have to jump through to claim the tariff. It's an onerous business and it wasn't clear to me. In particular, installers would be doing their customers a favour by getting them to claim as early as possible. A good few sunny days can go by before the FiTs are applied for and serious money can be lost, as happened to me last week.

So, onto the readings for this week. There wasn't as much Sun with a lot more Atlantic air passing over, so no maximum days:

Day 8: 17.5

Day 9: 16.1

Day 10: 13.7

Day 11: 15.5

Day 12: 5.5

Day 13: 11.3

Day 14: 14.0

That's a total of 93.6 units. However, day 8 was still prior to my FiTs claim so the financial return is less than it would otherwise be at £31.43. The running average since I started is 13.26 units a day which is excellent and well ahead of the 6.85 annual target. It's also becoming clear that when it comes to buying power, I'm using about 10 units a day less than before which represents about £1 a day financial saving on top.

One interesting fact during the week is that my son caught the inverter stating a momentary power output of over 3,600 watts. That's ever greater than the array's rated peak output. How can that be? Here's my theory:

A bright overcast sky can easily generate getting on for 1,000 watts, whereas a blue sky before the Sun gets to the panels generates only about 200 watts. I suspect it would be true to say that blue sky is relatively poor for solar power. So compare two situations. The first is where a bright Sun is in the middle of a clear blue sky. Presumably all but 200 watts of the power is coming from a direct Sun - say 2,800 watts. Now suppose we have a lot of broken cloud and a strong Sun shining through a gap. Could we then have 2,800 watts from the direct Sun and a further 800 watts of reflected light from the clouds - 3,600 watts in total? These numbers are just illustrative, but you get the gist?

FiT bureaucracy

At last I got around to registering my solar installation for payment of the Feed-in Tariff (FiT). Soon after my solar panels were installed, I was sent a certificate that I would use to claim for these payments because it certifies that my system is eligible. Then I got busy and the days ticked by. The panels generously provided valuable power but it has taken me a week to finally get around to making that claim. I did so today and it proved to be interesting. First, a recap of the FiT system.

Feed-in Tariffs are an arrangement whereby microgenerators (like me) get paid for every unit of electricity they generate, even if they use it themselves. If they don't use it and put it on the grid instead, they gain an additional small amount called an export tariff. All the major electricity companies support the FiT scheme and the money comes from a levy on all other electricity users.

To claim my FiT payments, I contacted the Green Energy department of EDF Energy, my supplier. They said I could apply by email but I would need to include a scan of some form of ID (my passport), a proof of address (utility bill), the invoice from Installation Company and a copy of the MCS certificate. I asked whether the initial meter reading from the panels (00001) would be used as the starting point for the payments. I was told that a meter reading would be asked for when I filled in the form and it wasn't to be backdated. As it was now at 00110, it means a loss of £45, the payment that would have been due for the first 7 days generation, had I got off my backside as I should.

EDF sent me an application form in the form of a PDF. I was at work and had hoped I could register from there, but having discovered I would have to scan documents, I would have to wait until I get home. When I did get in front of my computer, I saved the PDF to a folder and opened it to fill it out. It then told me that I wouldn't be able to save the completed form but that I could print it out for my records. I couldn't work out how I was to use this to apply by email.  I did check with EDF and the lady said they were getting many applications by email. Maybe I'm missing something. Anyway, I filled it in electronically and printed out two copies - one to send and one for my records.

All the forms and requsite scans were put into an envelope and posted to EDF. The PDF is a bit naff as it drops all the leading zeros, some of which are important in the likes of meter serial numbers and bank codes. I added them by hand. I guess had I been able to send it electronically, those zeros would have been included.

It's good to learn from EDF exactly how the FiT payment will work. At the start of every third month, I will send them a reading from my generation meter. They should then lodge the appropriate payments to my bank account within that month. I should therefore expect quarterly payments. For now, there is no way to determine what proportion of the solar power is fed to the grid and what is used here at home. Therefore, it is assumed that the ratio is 50%. This means that for half of the units I generate, I will get the basic FiT of 41.3 pence and for the other half, I will get an additional 3 pence.

One week update

At last, I have figures for a full week of generation by my solar array and it's been very heartening. The first two days were overcast so only five or six units were generated each day. For the rest of the week, however, we had glorious May sunshine and the daily haul jumped to a high of nearly 21 units. Here are the results:

Day 1: 4.9

Day 2: 6.6

Day 3: 18.2

Day 4: 20.8

Day 5: 17.1

Day 6: 20.2

Day 7: 17.5

If I add on the 4.2 units generated on the first evening it was switched on, this gives a total of 110.3 units for the week. The average generation per day was 13.7 units which is exactly double the 6.85 units I want for across the whole year. With the peak of the summer still to come, I'm hoping this keeps up. Once these units are converted to cash under the FiT scheme, the proceeds should be £45. An excellent result.

As the week progressed, the family began to take almost as much interest in the system's performance as me. My wife even phoned me at work to let me know how it was progressing. My son recorded the highest output power of the week at 3,398 watts. I'm very pleasantly surprised by this since the array is rated at 3,500 watts and it shows the necessity of installing an inverter that can handle all the power the panels can deliver. 

For most of these sunny days, the house runs entirely off solar electricity. Therefore, the number of units I have to buy daily have reduced from a typical 25 units daily to only 15, saving me a further £1 a day.

Meanwhile, Installation Company has sent me a certificate as part of the Microgeneration Certification Scheme which I will pass onto EDF to register for FiT payments. 

Two-day update

I thought I'd update followers on the performance of the panels after two days. I'll give a full week's update at the appropriate time. 

For the time between switch-on and sunset on Tuesday, a matter of roughly three hours or less, strong sunshine produced 4.2 units. Since then, the following two full days have been completely overcast and it's been interesting to see how the panels have performed. On Tuesday night, the inverter shut itself down once it sensed insufficient power was being delivered. I awoke at 5:30 am Wednesday morning and toddled downstairs to see how it was doing. Conditions appeared to be daylight outside but I was just in time to see the inverter power itself back up and tell me it was producing all of 4 watts.

Mid morning, we headed for the West End of town, but before we left, I noted a reading of about 250 watts. By the time we returned home, it still appeared overcast but there was now 750 watts being injected into the house. However, as I watched, it cranked itself up to 1,200 watts. It was obviously brightening outside yet it still appeared overcast. Happily, the retail meter had stopped ticking. The house was running on overcast! On Wednesday, we generated a total of 4.9 units.

Today, Thursday, was also overcast and I was at work all day. The folks at home couldn't remember the Sun having come out all day. However, the meter has clocked up another 6.6 units. Since the average daily figure I need for my target is 6.85, to nearly achieve that on a cloudy day is very pleasing. Given that a cloudy January day will be only half as long roughly, I expect those days will yield barely 2 units. 

So far, I should have clocked up £6.50 in FiT payments. Now all I need is a really sunny day to calibrate the top end of the range. My next blog will be when I have 7 full days of operation.

Installation - Day 2 - Power

It was the early evening when I got home from work but the Sun was shining and its photons were already pushing electrons around the house. It had been doing so since about 5 pm and had already generated its first unit. I was delighted. My WSW roof now carries 20 panels, each capable of generating 175 watts when the Sun shines directly on them; a total of 3.5 kW.

The installer showed me his handiwork. The 20 panels sit about 10 cm off the roof and have been connected as two 'strings' of ten panels each. The panels are connected in series so that the voltage from each panel is added with the others so the 44 V max that each is capable of becomes 440 volts DC total. A more typical voltage for each is about 35 V. In the attic, each string goes through its own isolator switch before running down the cavity in the wall to the cupboard under the stairs.

This cupboard is now lined with equipment. The two DC strings go into a large red unit, the inverter, which converts their power to AC, and does so at the same phase as the incoming mains power. Its output goes to a meter certified by Ofgen that measures the power being delivered by the system. Its reading is the basis of the payment of the Feed-in Tariff. Finally the power is fed through another isolator switch and a circuit breaker for high current protection before being merged with the house's main electricity supply.

At 5:40 pm, this system was pumping out 2,300 watts. The little red flashing light on our retail meter was flashing no longer and instead glowed a steady red. Amazingly, the entire house; all the computers, monitors, lights, TV and internet systems, fridge; absolutely everything was running off the Sun. Whatever excess power was left over was being fed to the grid. The middle of the day was obviously the time to run those power-hungry appliances such as vacuum cleaners, irons, dish washers and tumble dryers.

In this blog I've avoided identifying Installation Company. This is because they have a family connection and so I cannot make any unbiased recommendation. However, on this occasion, I'll make an exception to this anonymity. I'd like to thank the folk at Absolute Solar and Wind for their service, particularly Robert and Chris. The system looks great and it's working well.

So now the fun starts - and I'm delighted that tomorrow is a day off for me. The weather is supposed to be cloudy but I'll regularly monitor the instantaneous power output from the inverter to get an idea of its profile during the day. Tonight, I'll begin filling in a spreadsheet that I've already formatted and I'll start to carefully observe how the system performs over the coming year. My intention is to post weekly performance figures on this blog that will keep followers up to date with daily and cumulative performance.

My expectation is that I will generate 2,500 units annually which is an average of 6.85 per day. Anything over that will be considered a bonus. It has to be kept in mind that the first few months of this will across the longest and brightest days of the year. Generation will appear very good at first. However, the short days of winter will be a strong counter to the optimism of summer. Wish me luck!

Installation - Day 1

My prediction of yesterday didn't quite come off. There aren't yet any panels on the roof but there is a stack of them in the house and all the supporting rails are installed. I'm a very happy bunny.

One of the interesting aspects of this project has been the way its details have changed. This isn't a problem as I'm pretty flexible as long as my overall desire for the project comes off. To recap, Installation Company had originally intended to use Topsola 175 watt panels with a Sunny Boy inverter. Then it was going to take a while to get these items so we went for Sharp panels and a Diehl inverter. However, as it has transpired, by the time the installation came around, Installation Company had stocks of the original panels and the original type of inverter will be delivered tomorrow.

Today, the installers concentrated on the supports for the panels on the roof. They reported that they found the tiles quite tight and difficult to lift. They overcame this while the Sun beat down and, as seen in the photo, a set of four rails are in place to accept the panels tomorrow.

Another change was in the placement of the inverter. We started with the idea of having it under the stairs. Then it was going into the loft with some way of remotely metering it. This was to keep the cable run short - something the installers often do to reduce power losses. Then it was going into a cupboard in an upstairs bedroom for ease of access. Today, it returned to the cupboard under that stairs. Part of the rationale for this was due to the wall there. It used to be an outside wall and thus has a cavity. It was easy for the installers to make a relatively straight run of cable down that cavity. Since I take all my other meter readings in that cupboard, I might as well take the solar reading from there too.

If the inverter arrives tomorrow, the system should be running by day's end. Spreadsheet is primed and ready to roll!

Panels day

It's a beautiful, sunny May Monday morning. Solar photons are flooding in the east-facing windows of the house, and by the end of the day, they'll be striking a huge array of photovoltaic panels on my west-facing roof. 

The installers should arrive in an hour to begin installing 20 panels. I'm hoping that when they do, they manage to leave room for a future thermal panel. Normally a system of this size would take two days to get going. However, I believe the inverter won't arrive until later in the week so I have to wait a few more days before I can generate valuable power.

I'll be at work all day so I won't get to watch progress. I'm looking forward to seeing the results however.

Installation imminent

Got a phone call from Installation Company to let me know that they intend to begin installing my panels on Monday. I didn't take the call myself and the message that was passed on said that apparently they are having problems acquiring an inverter. As a result, it will be installed later in the week. That surprised me as I had thought we had agreed to change from one brand of inverter to another specifically because they were easier to get hold off.

Meanwhile, and unintentionally whetting my appetite, my brother-in-law happily informed me that his south-facing array had produced just over a hundred units in its first week of operation. That is an average of over 14 units a day. The extremes were as many as 20 and as few as 5. Another way to look at it is that he's earned over £40. Nice earner.

Unfortunately, I'm working most of next week so will miss the work being carried out.

Starting gun

An important step forward was taken today when I paid the deposit for the solar array. I am impatient for things to get going.

To slake my thirst a little, I visited my brother-in-law's home where he is in the process of having a system identical to mine installed. It looked great and it ought to be pushing electrons by the end of the day. Perhaps the installer saw how I was salivating at the idea of having mine up and running, but he mentioned, perhaps in jest, that he might have to work over a weekend to get mine going asap.

Watching the inverter getting taken up to the attic made us think more carefully about where we ought to place ours. The original intention was to place it under the stairs. However, it was pointed out that there was significant power loss if the cable run from the panels to the meter was very long. Also, it's a big brute. At 70 x 30 x 25 cm, it is twice the size of the one we were originally to have and would barely squeeze into that little space. The preference was to have the inverter in the attic, with the meter next to it. But I want to read the meter nightly. There were thoughts of having a wireless webcam installed to allow me to see it from my computer but issues of providing lights were making this less than ideal.

After seeing the installation today, we thought a better place might be one of two cupboards we have in the upstairs bedrooms. The cupboard in our spare room seems the best place. It's not far from the roof and is directly above where the power enters the house. It's accessible and won't require a webcam or remote meter.

There was one other small step in this project that occurred today. EDF Energy wrote to let me know that our energy supply moves over to them on 7 May. As part of that, they asked for an electricity meter reading which I supplied by phone by speaking to a computer. It all worked successfully. They say I'll get another letter soon, asking for a gas meter reading. Ignoring for the moment the solar panel installation, I expect my £2,000 annual energy bill to drop to at least £1,500. The panels and the Feed-in Tariff (FiT) payments should make a huge dent in the remainder.

From dreams to reality

This solar project is nearing fruition and I'm back to waiting; waiting for Installation Company to acquire all the equipment needed, and then come and install it on my roof. It occurred to me that maybe I should compare my initial hopes for this project with the reality I have since become aware of as I have studied its details.

The major difference between late February and now is the change in the government's system of grants and loans. Then I had expected that nearly the full cost would be covered by a £10,000 interest-free loan and a £4,000 grant. This has since been descoped to a mere £4,000 interest-free loan. I had just missed a window late last year where these schemes would have been available and so most of the finance must come from our own resources.

A more subtle difference comes in the amount of power I can expect to generate. When a lady from Energy Saving Scotland visited, she pulled out tables that said a south-facing array of the size I was planning ought to generate 3,100 kWh annually. I had seen a table on the web that suggested an east or west-facing array ought to generate 90% of that figure. That gives 2,790. However, I was thinking of a 4-kWp array and it transpired that a smaller array, 3.5 kWp, was a better plan to avoid the power company having to do a feasibility study. Looked at now, that ought to generate 2,440 kWh, but maybe I would get a little more as my roof is 20 degrees south of facing west. Yet somehow, I was going through this whole process with 2,900 annual units in my head.

Part of this was because when Installation Company quoted for my system, they suggested it ought to generate just over 2,900 kWh. That seemed about right - it appeared to be around 10% lower than the figure I had heard originally and I had assumed that whatever figures they were using, they had taken the orientation of my roof into account. However, on speaking to them last Friday, I discovered this orientation was new to them. They thought I had a south-facing roof. Their revised quote that I got later that day was appropriately adjusted. Their calculations, based on government tables, and assuming an east-west roof, is now 2,480 kWh annually or 6.8 units a day average. That matches my own new calculations.

So a new reality is setting in, but I can accept this gradually declining expectation of my roof's generating abilities as the figures still look good in the spreadsheet. What does it say? Using the new figure for annual generation, the difference between installing and not installing the panels is now £25,300 in my favour over 25 years, down from about £32,300 before. I am looking forward with glee to the 365 days that will come after the installation is complete when I will see how accurately this final prediction compares to reality.

When I visited a house with a panel array already in place, it was cold but sunny. Being February, the days were still short. Yet this array, the same size as mine but south-facing, had generated 15 units of power that day. Its current performance is 9 units a day average over the months of February, March and April which translates to 3,285 annually. Given that this period is biased towards shorter days, this system seems to be outperforming its expectations by a significant margin and it has made me think that the government tables are somewhat pessimistic. Time will tell.