Free electricity from the sun?

I first took an interest in solar power generation in the summer of 2010 when a number of companies began to advertise free installation and free use of the electricity generated. I have been (but this year, 2011, I’ve been trying to reduce it) a fairly heavy electricity user, nearly 7,000 kWh per year due to constantly operating pumps for a garden pond, quite a lot of computer equipment running 24/7 and a home cinema system that in theory draws more than 2kW when operating at full blast - though probably a good deal less in practice. I believed that I should be able to use a high proportion of anything generated locally with higher than average saving in electricity costs.

I registered an interest with Homesun who were advertising free installations heavily and they sent a salesman to do a preliminary survey. My experiences with Homesun are reported here. In my opinion they do a fairly good impression of a company with minimal interest in customers and wholly focused on enriching themselves. I received much better service from a local company, Solstice Energy.

Although I did a great deal of research on the web about the viability of solar panels and asked the experts at Solstice Energy many questions there is nothing like observing a system in operation to really get to grips with the practicalities. To possibly assist others in their own research I shall post figures on this website relating to my system’s on-going performance.

One claim I picked up from enthusiastic owners who had posted information to forums is that on cloudy days the output would remain above 20% of that on a sunny day. Homesun’s website is inclined to perpetuate the myth with their slogan “It even works in Winter”. I should have known better; energy cannot be created and anyone who has played with a photographic exposure meter will know that brightness levels vary widely. In the worst cloudy conditions the power output is barely one fiftieth of what it is if the sun shows its face.

For the first two months following my installation the weather could only be described as foul with the sun missing throughout February making a new solar owner feel rather depressed about the investment but a superb April transformed all that with that month’s output running about 40% above prediction boosting the output since installation date to nearly 20% above prediction. It’s very clear that the Winter period counts for very little. It produces next to nothing on good days and if you lose the lot it doesn’t amount to much. A poor Summer however would be a disaster.

In good periods such as April 2011 I have found it absolutely impossible to use a significant proportion of the electricity generated and personally I have given up trying very hard. The money is made via the Feed in Tariff, not by saving electricity, and if I had gone for a rent-a-roof scheme all the glorious April weather would not have benefited me at all, or at least not by more than a pound or two.

See the blog for an ongoing report.

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