Solar Blog 2013


An above prediction December but nevertheless the worst in three years and even twice almost nothing is still nothing. Overall, another disappointing year compared to 2011.

Over the past three years various rounding errors have begun to make a nonsense of some of the recorded data. The generation meter is more than 1% in advance of what the inverter reports and the daily summary of output provided by the Sunny Webbox varies slightly from what is recorded internally and extracted for the monthly graphs.

Not sure what can be done about it but if possible an adjustment will be made for January 2014 to make things look right - even if they are not perfect

Month’s generation : 83·69 kWh.


On Radio 4’s Gardeners’ Question Time I heard the expert looking for reasons for a poor Brussel Sprout crop say that the cause is the very poor light levels experienced in 2013. Good job someone else has noticed how bad 2013 has been.

Month’s generation : 131·16 kWh.


On the 21st of October the year’s generation reached 100% of the installer’s annual prediction. 21st October was the 294th day of the year.

In 2012 the 100% mark was passed on the 274th day. In 2011 it was achieved on day number 263.

Contrary to the general perception, 2013 has been a relatively sunless year.

Month’s generation : 190·34 kWh.


On the 1st of September the total generation for 2013 overtook the total on the same day in 2012. However it was still 85kWh behind 2011 despite that year being six days short due to the 7th January commissioning date.

By the end of the month generation had fallen 118 kWh behind 2012. The widespread belief that 2013 has been a good summer is a myth. It was an excellent July and the rest was merely average or far behind last year.

Month’s generation : 262·32 kWh.


The summer is said to be a particularly good one, so why is the total generation this year no better than any other? The table below may help explain it.

The miserable start to the year should not be underestimated. The losses in the first three months, compared to last year, were 42, 60 and 141 kWh respectively and 243 kWh is a lot to make up. April clawed back 60, May 10, June another 30 and July 100 but despite August being a sunny month it was only 20kWh better than last year. (An extra 6% of the predicted 350kWh.) However it got close to making up the shortfall.

Month/Year Prediction 2011 % of prediction 2012 % of prediction 2013 % of prediction
January 77·81 * 59·32 95 116·93 150 74·38 96
February 119.56 95·52 80 184·91 149 124·63 104
March 226·92 264·69 117 322·65 142 181·46 80
April 301·50 444·18 147 318·07 105 377·45 125
May 373·24 484·26 130 368·62 99 379·97 102
June 381·00 421·54 111 359·11 94 390·00 102
July 375·10 427·02 114 395·68 105 496·62 132
August 351·54 350·50 100 403·58 115 424·60 121

* 62·75 for 2011 due 7th January commissioning date.

For convenience the figures are also presented as percentages below. This is the same table that appears under the ‘Monthly output’ menu. As it is dynamically grabbed from that page it will auto update the later months as the year progresses.

2013 - Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Prediction 2.51 4.27 7.32 10.05 12.04 12.7 12.1 11.34 9.29 5.94 3.45 1.83
Achievement 96% 104% 80% 125% 102% 102% 132% 121% 94% 103% 127% 148%

2012 - Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Prediction 2.51 4.27 7.32 10.05 12.04 12.7 12.1 11.34 9.29 5.94 3.45 1.83
Achievement 150% 149% 142% 105% 99% 94% 105% 115% 129% 107% 136% 152%

2011 - Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Prediction 2.51 4.27 7.32 10.05 12.04 12.7 12.1 11.34 9.29 5.94 3.45 1.83
Achievement 95% 80% 117% 147% 130% 111% 114% 100% 125% 149% 102% 175%

I received an unwanted letter from Scottish Power on 30th August. They have suspended my FIT account and the reason given is that I have refused admission to their meter reader. The generation meter not the supply meter.

This is of course the sheerest rubbish, I am at home nearly all the time and the generation meter was read last February. They not only read it they took photographs of it. Apparently the meter reading company is G4S. First they try to wreck the London Olympics and now they try to wreck Scottish Power’s reputation; mind you, Scottish Power are perfectly capable of doing that all by themselves. Automation of their FIT service has produced nothing but a steady decline in the service. Still better than some other companies I am informed, but definitely much slower than it used to be.

Month’s generation : 424·60 kWh.


Generation has only gone through the 400 kWh barrier five times before (four times in 2011 and once in 2012) but this month it managed 501. On the generation meter anyway, the inverter under reports by 1%. See figure below.

Despite being the best month ever, 2013 is still lagging behind 2012 by 41 kWh - and 2012 was not up to 2011’s standard.

Month’s generation : 496·62 kWh.


Another lousy month. Mid summer but little better than April.

Month’s generation : 390·00 kWh.


Err… Rubbish!

Month’s generation : 379·97 kWh.


A late surge of sunshine at the end of the month lifted the yearly achievement to more than 20kWh above prediction for the first time this year. Still nearly 200kWh behind last year though.

Month’s generation : 377·45 kWh.


The FIT service provided by Scottish Power continues to go downhill. Since they automated their systems the minimum acceptable interval between generation readings has increased first to 80 days and then 84 days and now it would appear to be 90 days.

A neighbour submitted his reading last month only to have it rejected for being too soon. They told him he must wait 90 days. As he sends his readings in only on the last day of the third month - in this case on the last day of February - it was an unexpected response. Somewhat bemused by Scottish Power’s inability to read a calendar he complained only to get a rather rude email from their Dorothy Taylor.

As far as I can ascertain his 30th November reading and submission was entered on to Scottish Power’s system six days late. The end of February reading went through the system more quickly, hence their ‘less than 90 days’ complaint. I think it may be assumed that Scottish Power’s originally excellent FIT service has been seriously degraded in the name of progress.

Month’s generation : 181·46 kWh.


The only thing remarkable about February is that the electricity meter reader wanted to read my generation meter. Now that's a first! He photographed it too.

Month’s generation : 124·63 kWh.


By far the worst month since installation. Snow obliterated generation on three days because the ‘avalanche’ was caught on the pigeon deterrents. By the third day only the lower rank of panels was obscured and only by about 25% but generation remained close to zero. A neighbour’s installation was clear of snow and generated 1·4 kilowatt hours on that third day.

The installer suggests the panels were arranged in a left right string arrangement rather than the more obvious top bottom. There is no very obvious reason to have done that.

Month’s generation : 74·38 kWh.