Another year, another desperately late solar panel performance post. It’s been sitting on my to-do list since January 2nd, but at least writing this will let me tick off something today.

So last year continued a downward trend that looks like it will be over by the end of 2013. At this stage in the year, the graph is the only source of information still recorded so we’ll have to guesstimate the heat output as 3666kWh.

Nottingham Energy Partnership have an Energy Costs Comparison table. I neglected to look at it last year, so will have to use the data from last month now to estimate the financial value of the heat we got from the sun. I use the gas rate of 5.06p/kWh, since if the water were not heated by the solar panel, it would be heated by gas. Interestingly this appears to be a lower cost than last year’s gas cost.

That means the solar panel gathered around £185.50 of energy last year.

The running total to the end of 2012 is therefore £831.06.

There are all sorts of flawed assumptions being made to come to that figure, so take it with a fairly large pinch of salt.

This year I have had my annual half-hearted attempt to work out if it’s possible to do more comprehensive data logging using the equipment I have. I did pay extra for the ethernet connection with the idea of putting some sort of graph on my website to show how the system is doing in real time. I’m super jealous of this guy who has done exactly that with the same setup as me. And as a favour to everyone else he has made public the code to do it. And I don’t have a clue what any of it means or how to use it!

If you are considering a solar panel of your own, whether for hot water or to generate electricity, and you live vaguely near Nottingham, do please get in touch with Sungain at Nottingham Energy Partnership, who would be delighted to let you know what to do next. You can also follow them on Twitter, and they also have a very helpful service on their website that lets you compare your electricity and gas tariffs and see if you can save money.

Buckets more information about my own solar panel under this link.

And a declaration of interest: I’m on the board at Nottingham Energy Partnership, where they very kindly describe me as an “energy expert.”