30 May 2009
I think the intent of this article is excellent, but please make sure your facts are correct. A Watt is a measure of power, not energy. The incident radiation at best in the UK is around 800Watts (cloudless sky, mid summer) due to our lattitude. I suspect that the article should have been 1kWh (1000Wh or 1000 watts for an hour).
1kW hour unfortunately only costs about 8p which is not (currently) enough to payback the investment in solar panels. If we are to build a credible case for low carbon energy systems we must be both accurate and realistic in our message.
01 Jun 2009
I believe that we need to eliminate the "payback" concept from the whole discussion. The entire capitalist system that the concept belongs to values only "capital" and "labour". The environment is simply an externality with no cost associated to it. The 8p is simply not a true "cost" so the "payback" figure is nonsense. People love to buy things; it is how we have structured our society. They should be wholly encouraged to buy solar systems, insulation, wood fuelled boilers, energy monitors, anything that makes a contribution. Obviously, it is even better if they make a difference in key areas and there is a great and simple description available in David Mackay's book Sustainable Energy; Without Hot Air, which can be downloaded free of charge at
01 Jun 2009
@nextgenheating - thanks for your comments.
To clarify - we did mean 1000W (we used . Over a year, this could mean about 1,200 kWh, or about £100 per year in wholesale electricity costs. However, the economics of renewable energy aren't quite so straight-forward.
I think you'll be interested in by The Guardian's Ashley Seager, showing that the return for his solar panels was nearly 5% - better than most savings accounts will offer.
Thanks for pointing out that the story could have been clearer - we'll endeavour to take that on board.
For what it's worth I agree somewhat with @hforbes in that I'd rather have 1,200kWh of electricity a year than £100. The cost or price of a commodity often only represents its relative value - not the true value. Come a power cut or greatly increased electricity prices, an investment in solar panels would surely increase in worth?
02 Jun 2009
The EU supported PVGIS website gives the projected output from a solar PV array, for any location in Europe: . For southern England, e.g. west Kent, output is 880 kWh per kWpeak installed array capacity per year. Rather less than David's figure; but if we get a decent feed-in tariff, ideally following the highly successful German model, PV will be affordable and financeable in the UK. And the more capacity is deployed, the more the cost falls – that is the experience of the past 20+ years.