Solar Blog 2011

The only noteworthy things to have happened this month are that…

1) The pigeons seem to have found somewhere more comfortable to live than my roof.
2) My energy supplier sent a refund cheque of £445 (for 10 months) after they had been grossly overcharging me by direct debit and reduced my monthly payment by £20. The reduction looks to be about half what is justified. The moment my contract expires I shall punish them by switching to someone else - and probably equally dishonest!
3) The sun shone in the first half of the month on approximately alternate days providing an unexpected bonus.
4) Generation seven days short of a full year of operation was 120·6% above prediction. This is higher than recorded on the spreadsheets etc. as the logger under-records the generation meter.

Month’s generation : 99·18 kWh.

Microbee showed up by arrangement on 3rd November and reattached a total of five pigeon deterrents, four of which were on the top ridge and out of sight. They admitted they had used a different glue because their usual one was temporarily unavailable. They provided a written assurance that they would inspect the installation after the winter snow to see how the adhesive had stood up to it and refit them with silicone, it currently being too wet to do it now.

Microbee returned on 14th November and added to the armoury of deterrents and improved the existing arrangements. Birds had found a way to bypass them - one set of spikes was bent in a less than ideal direction. It seems that for the time being the pigeon problem is reduced, they are now congregating on a neighbour’s roof. The real problem is an idiot who lives about 200 yards away who dumps huge quantities of bread in a nearby park. So many pigeons fly over when he does that that it is impossible to count. One hundred plus. I have seen more than 50 on his own roof.

Month’s generation : 105·61 kWh.

The unexplained loss of a day’s data from the data logger’s ‘front page’ report on 30th September corrected itself the following day. The logger presumably syncs with the inverter occasionally and removing the memory card for a short while must have confused something.

On 11th October a third nearby house was adorned with solar panels, nine south facing. It means that three out of six houses in the same road are now equipped with PV. Although only five houses away I do not know the occupier, there is quite a long gap between the fifth and sixth houses from my address.

Scottish Power managed to get the FIT payment into my bank account via BACS in exactly two weeks after sending them the meter reading.

On 17th October I bumped into the owner of the new system five houses (but a fair distance) away from me. I did know him after all. He said his system is 2.1kW and was installed by a company that came from north London. Three men did the job in a day with the scaffolding efficiently installed and taken away in a 48 hour window but he was having problems with the MCS certificate. Solstice Energy sent mine via email within hours of job completion but he was having to chase for a copy which was now in the post and British Gas, his chosen FIT partner, were not going to allow him more than five days of retrospective meter reading.

A week or so ago I noticed that part of the pigeon deterrent system on my neighbour’s roof had fallen off. Yesterday some of mine fell off and today (23rd October) a bit more. One of the set of spikes has been retrieved and has very little adhesive on it. Fortunately that spike section is easily within reach with a ladder. The adhesive appears to be No Nails or similar when I had been told it would be bathroom type silicone sealant.

Inspection (20th October) has shown many of the pigeon deterrents within reach to be close to falling off, I have replaced the missing one with silicone. It is odd that Microbee has used ‘No Nails’ when it appears not to adhere to their plastic based spikes. If they had no experience of sticking to aluminium and it failed to adhere I could perhaps understand it but it is their own spike system which has failed to stick. It is going to be difficult to remove all that glue, one accessible section was tricky enough, the rest are going to be a problem.

The spikes continue to fall off one by one and I have used silicone to put them back. Microbee have agreed to return to look at and remedy things next week.

Month’s generation : 274·32 kWh.

My neighbour called in a pigeon control company which has been around and attached the usual spiked deterrents around the edge of my panels with bathroom style silicone goo. I was well pleased with the company’s service. They were friendly, helpful, arrived on time, did not kick up any fuss about the lack of scaffolding and did a neat job, if you can call spikes sticking out all round my nice shiny panels neat. The pigeons seem to have gone already, but time will tell. The cost was only £225 which if the spikes are effective will be money well spent.

The company goes by the strange name of Microbee and I can thoroughly recommend them if you have a pigeon problem in or around London.

At 12:50 on the 23rd the generation meter passed the total prediction for the year 7th January 2011 to 6th January 2012.

On 30th September the data logger lost the day’s generation from its total generated figure, so the logger is likely to lag behind the spreadsheet by 15·57 kWh for ever more! The memory card was removed, after dark, for the first time since installation.

Month’s generation : 347·76 kWh.

Pigeons have become a serious problem. I have raked out two nests and there is a third out of easy reach. Small sticks are constantly falling into the gutter and partially blocking it. At least two young pigeons have been reared under the panels and it is now obvious that the roof brackets are simply too tall or that the tiles are too deeply ridged. Whichever it is the gap is too big and crouching pigeons can get in from all sides.

When I was considering the installation of solar panels last year I picked up a lot of information from the posters on the Money Saving Expert forums and realised how useful user comment could be. That is one reason I maintain this website and many people have told me they have found it useful. However if I answer a question posed on the Money Saving Expert forum and refer to this website for more information my post is rapidly deleted. It would appear that MSE doesn’t really want to help its members at all. It wouldn’t be the only forum where absolute power has corrupted absolutely so I no longer visit it. It is no loss to me but unfortunately MSE's priority being to protect itself will in a small way adversely affect the people it purports to want to help.

Since January two people have knocked on my door to ask about my solar panels but one that didn’t from the same street had 12 panels put on his roof in a row of ten at the highest level and two below on the right. The roof faces precisely west and the reason for not having more appears to be that they could be shaded by the roof of the house next door. Even those two panels may be shaded by the same roof in the late afternoon of the summer months when the sun sets to the north of west. The roof is inclined at 40° to the horizontal which is far from optimal for west facing panels and there is a tree at the 1 p.m. to 2 p.m. position which could shade some panels in the winter months. The installation was completed in less than a day (24th August). Perhaps the cost was considerably less than my own.

In its first seven days of operation the west facing installation, with due allowance made for differing system sizes, generated 2.2 times less power than my south facing one. This page suggests that the mornings may have been a little better than the afternoon during the period in question. (25th to 31st August 2011.)

The panels are fixed a little higher from the roof tiles than my own so I warned the householder of my pigeon problem. He reacted by having the scaffolding retained while a pest control company considers the options.

It’s been a rotten August hasn’t it? My system cut out one afternoon, it was so dark. How come I have still equalled (†) the prediction?

† In fact, beaten it by 1% because my generation meter reads 1% higher than the stats collected from the inverter.

Month’s generation : 350·50 kWh.

July was rather disappointing in that there were only two days that got near to approaching wall-to-wall sunshine and a ‘bell graph’ output and far too many days of solid cloud. Fortunately there were enough sunny intervals some days to push output a bit above prediction. With several months’ weather this year being poor but output above average nevertheless it probably proves what we already thought, that British summers are always mediocre at best.

Following a suggestion from a poster known as DigitalToast who posts on the MoneySavingExpert forum, all the graphs on the site have been recreated as PNG files rather than JPGs and the Excel sheet scripts modified accordingly (on 2nd July). He suggested the file sizes would be reduced by a factor of four; he was wrong, the saving is around ten times. Much appreciated DT, I’ve not used PNG format before and it seems I have been missing out.

On 3rd July a somewhat crude picture of the entire year’s output was added to the ‘Daily output’ page; consistently sunny days have been few and far between! For convenience the link is repeated here. Despite the use of PNG it is quite a large download, currently just over 700 kilobytes.

On 7th July the Excel spreadsheet script that produces all the graphs was modified so that it may optionally be auto-run on start up. Don’t even have to press a key now!

Month’s generation : 427·02 kWh.

A new menu item has been provided. ‘Daily output’. It allows a choice from any date since 7th January and see a graph of that day’s output. Each figure is an average of the output over 15 minutes.

The ‘Performance v Target’ page available from the ‘Monthly output’ top level menu was frequently left out of date due to forgetfulness. As from 10th June it updates dynamically whenever the monthly graphing routines are run. i.e. generally daily.

By the end of 3rd June the system passed the 50% mark on its way to producing the full annual predicted output - and it didn’t start until 7th January. NB. One day in advance of the spreadsheet indications because the generation meter runs 1.1% in advance of the data logger.

On 7th June while clearing a gutter I found two pigeon’s eggs that had rolled out of a collection of sticks accumulated around one of the panel roof supports. On the 14th a dead pigeon was scraped out from underneath the panels.

June was a generally disappointing month, true it beat the prediction, but compared to much of the country the South East had rather too much cloud. There were only three days that produced a close to perfect ‘bell curve’ indicating sunshine all day. I have a page that shows that graphically and will consider how it might be included here.

Month’s generation : 421·54 kWh.

It was pleasing to note that at the end of 6th May, one third of a year following installation, generation levels had reached 34.44% of the installer’s predicted output for the whole year with the summer still ahead of us. The amount of electricity being produced is embarrassing as my meter goes backwards so my consumption has been showing as about eight units a month! My supplier has been advised of the meter’s foibles and I’m inclined to think that that makes it their responsibility not mine.

Thanks to an enormous amount of work put in by a skilled friend the graphs which may be found via the Statistics menu are now automatically produced by a single click on an Excel spreadsheet plus one OK acknowledgement. Amazing! The spreadsheet produces much more than the graph shown here but is only usable in conjunction with the SMA webbox.

Month’s generation : 484·26 kWh.

What a difference! One totally dud day on the 5th, a few close to prediction but most well above it. The 20kWh per day barrier was breeched and the month was an astonishing 47% above prediction. My supplier, who keeps an eye on this site, sent me a revised pay-back forecast - less than eight years. It’s actually better than that because installation caused me to review my electricity consumption. That and the generation in the first quarter of this year puts me on course for a better than 4,000 kWh reduction. That’s at least £400.

I have been informed by a more recent customer of Scottish Power that they have commenced acknowledgement of FIT application forms which is good to hear because it was my only complaint. They paid £181.90 into my bank account promptly just three weeks after the 31st March meter reading. Thanks to April’s weather they owe me more than that already.

Month’s generation : 444·18 kWh.

The good news is that Homesun have returned my £100 deposit from when I considered a rent-a-roof system and that March while providing generally poor weather over the first 20 days or so, has seen lighter cloud cover. The last ten days were mainly much better with several glorious bright days. Totally cloudless days that could hardly be better provide an opportunity to compare my system’s 30° precisely south facing unshaded roof’s output with others across the country who also report cloudless skies. Such comparisons are consistently showing that my panels under-perform the other three systems by up to 15%. I was regretting not putting more searching questions to my supplier about the possible benefits of costlier but more efficient panels but then it became apparent that although my peak output wasn’t up to a few other systems I was watching, my total for the first 20 days of the month was higher. It seems I am doing much better on poor days which has made me feel much happier.

My supplier has referred to me to some Windows software which enables all sorts of ‘what if?’ style questions before purchase. The software costs nearly £600 but there is a 30 day evaluation version available for download from the University of Geneva. Not for the faint hearted but far more sophisticated than any of the web calculators I have looked at.

Scottish Power with whom I have my FIT agreement have written to me requesting a meter reading on 31st March so that they can apply the new tariff from April 1st. They have promised a cheque before the end of April. What with that and the fact my total power generation is now running ahead of the supplier’s prediction despite an appalling couple of months of fog and cloud, things are looking up at last. The dramatically reduced electricity bill is a bonus too. Paid consumption is down by two thirds, though it is true I have been trying hard to make economies.

Month’s generation : 264·69 kWh.

The 3rd of the month provided the first sunny day when I had time to play with the system although even that was spoiled by light cloud until mid-day. My monitoring tools consisted of the SMA data logger (see Today’s output) which requires my desktop computer to be running to see it - a bit of a waste there - and then running outside to watch the electricity supplier’s meter go round and round. (One revolution in just over 2.5 seconds equates to 1 kWh on my unit but they are not all the same, my neighbour’s spins at a different rate). So it’s not very practical. I have looked at monitoring kit but as the only one suitable for input and export use takes 5 watts of power and costs far too much it won’t make an appearance here any time soon.

The month has remained exceedingly gloomy in London. Day after day the forecast says sunny intervals except in the South East which will be covered with cloud. Cloud may not be too bad but all I have seen is a solid blanket of fog hanging on the nearby hill and car headlights on all day. There was a sunny day on the 8th and a couple of sunny afternoons and one or two hours of just discernible sun at other times but for the most part it has been impossible to get any idea whereabouts the sun is in the sky because it has been well and truly obscured.

On 21st February Scottish Power finally got around to agreeing my FIT application and sending me some documentation. An acknowledgement of receipt of the application would have been nice to save the six weeks of concern that it may have been lost in the post. I returned the signed acceptance form the same day. No acknowledgement of that either. It’s not as though it takes much effort. They know my email address.

I am beginning to regret not being more assertive about the choice of panels and maybe choosing those with the best low-light performance which might trigger on earlier in the day but on the other hand there isn’t much electricity to be generated in such conditions so maybe the extra cost would not prove to be a good investment. Right now, in the SE of England, solar is not a good investment anyway. It is making a profit compared to interest on money in the bank but the payback period looks like being around my 110th birthday.

Month’s generation : 95·52 kWh.

It was probably a mistake to agree to an installation start date of January 4th with an eclipse of the sun due that day, it seems to have been an unfortunate omen. The sun shone the following day but it rained on the 6th and half drowned the installers and the unremitting gloom persisted all month. Output was frequently around 1% of the theoretical maximum and some days were so dark that the house lights were on for most of the day and the inverter didn’t switch on until 11 a.m. Thanks to an unexpected sunny afternoon on the 31st which pushed output above 2kW a thoroughly dismal month finished up only 5% down on the prediction.

Contrary to what the optimists had led me to believe thick rain clouds seem to be very bad news for solar panels and a typical constantly cloudy day gave well under 10% of the output of one with a few sunny intervals. The sun is what makes the difference between profit and loss. See Statistics>History for details.

By the end of February the sun will be twice as high in the sky and the days fifty percent longer. As Spring approaches the system should begin to pay off but so far the Feed In and Export Tariffs combined have exceeded the loss of interest on the investment by only five pounds even at the lowest assumed rate of interest. Compared to long term bond rates things do not a look good at all. But it is Winter!

Month’s generation : 59·32 kWh.