On average for last year (until 26th March 2012) we used 15 units daily of electricity. (The average for the year before was 20, so we had already reduced our consumption by 25% simply by being economy minded and me nagging Mike to remove one of the constantly-on computers). Now my current calculation is we are using just under 10 kWh per day. This is a saving of 5 kWh per day or 60p at 12p per unit, so by my reckoning we are saving £200 per year in outgoings.
We are also earning 21p per unit generated so we have just earned £210 for this quarter, and we will assume that we have 3 quarters of £210 and 1 quarter of £70 just to make the maths easy. so all in all we will earn £700 in government funded revenue from our panels. (feed-in tariff)
Now also there is an assumption by the electricity company that we are using half of the generated amount of electricity and so there should be another payment of 3.2p per unit of unused stuff (export tariff). This means that we will also earn another £100 for the year.
This means that for the current expected year we will save/earn £1000, so at £8500 expenditure we will get our money back in 8-9 years. Of course if we had our money in the bank it would have got us some interest so we will allow another 10% on the outgoings and therefore we should break even in 10 years.
Now all we need is a jolly good sunny summer and we will be well over our target :-)
