Sooo..after roughly a year, here is a chart showing the solar output from my 2.1kwp ground mounted solar array outside my office window: (The left axis is kilowatt hours, so 1,000w for an hour, or one ‘unit’ of power in the UK).
No surprises really, the usual solar chart, but without all the randomness removed, and showing just how variable things are. I think the reporting screwed up for a few days in February where it suspiciously reports exactly 0 data. If I take a rough approximation from my energy bill, it looks like we use 5.7 units of power per day on average. That’s pretty low. It means we use 2,107kwh of power a year, which compares amazingly well with the data on this map:
http://www.guardian.co.uk/news/datablog/interactive/2012/apr/02/energy-use-map-electricity-gas
But it’s not all good news… if you adjust that graph to show 5.7 units as the base line you can see where we are exporting, and where we are importing power…
Yikes, that’s kinda scary, there are times even in summer where we couldn’t cover our power usage, and winter is just a disaster. Of course, this assumes a constant power consumption per day, because we don’t have a ‘smart’ meter, and have no real idea, but it’s an interesting stat. Our power generation over those 365 days is 1,276 units, so it’s 60% of our power usage. The cost was about £9,000, which means buying enough home-grown capacity to make you zero-bill would cost about £14,800. That isn’t *that* bad when you consider it’s about 10 years electricity bills, and the panels last 25. but….. The cost of these panels has dropped like a brick, to about a third of what we paid. So in fact, the cost should be about £5k now, to be zero-bill over the year if you have low energy use like me. Also be aware we have an electric cooker. oh yes.
And actually…that’s WITHOUT the feed-in-tariff or any export payments. That’s purely looking at energy prices and installation costs. That’s also with an inefficient ground mounted array in a very shady garden in cloudy south UK.
Have I done my sums all wrong, or is this excellent value for money?