Feed-in Tariff - winter payment

The Feed-in Tariff payment for winter arrived today - I was expecting it to be fairly paltry, and I was not surprised.

For a total official generation figure of 172.25kWh for Dec/Jan/Feb, we received:

Generation payment -
172.25 x 14.9p = £25.66

They assume we export 50% of what we generate back to the grid, and pay us 4.64p per kWh for that.

Export payment -
(50% x 172.25) x 4.64p = £4.00

So we received a total of £29.66 paid into our account.

Because I work from home and have computers, printers and heaters/air con etc running from 9 til 5, we didn't actually export any of our electricity back to the grid, we used all of it ourselves.  But we still get paid for the assumed 50% export. I've read through all the small print, and there's nothing anywhere to say what to do if you think the assumed export value is incorrect, so I'm in no hurry to tell them about it.

Consequently, you stand to get the most financial benefit from solar panels if you use every drop of solar generated electricity yourself - particularly as electricity prices increase - because that's all electricity you're not having to buy from the grid.

We're with npower, and our electricity tariff has just gone up to 15p per kWh, so we've saved 172.25 x 15p = £25.68 this winter on electricity we would have otherwise had to buy from them.

Added together, this is a total benefit to us of £55.34 for the three months Dec '13 + Jan '14 + Feb '14.

Here's a running total of the overall benefit so far:

Autumn 2013 £92.50
Winter 2013  £55.34
----------------------
Total            £147.84

February's Generation Stats

Here's the graph for February's generation from our array of solar panels. This is for our 2kW 8 panel solar array (Panasonic HIT panels), mounted on our south-facing roof at approximately 35-40° angle from the horizontal.

The dark red line is February.  I've included December (being the lowest month for solar generation) by way of comparison.  Having the winter solstice bang in the middle, it is completely flat to all intents and purposes.  February shows a clear trend of the graph climbing towards the end of the month.  I was quite surprised how quickly the generation has picked up as we make our way out of winter, topping 8.5kWh for the one day 27th February.

Here it is on the yearly forecast chart:

As you can see, February's generation has exceeded the forecast amount (by 13.54 kWh).  This is 16% higher than the forecast. Quite reassuring given the poor show by December and January.

To catch up on the deficit from winter's generation, March-August will need to outperform the forecast by 3.5% to achieve the total forecast value for the year of 1645kWh.

Here is a graph to show the 'value' of daylight during each month.  It shows how much electricity (on average) is generated for every hour of daylight of the month (from sun up to sun down each day). Note, being an hourly value, this is not affected by the varying amounts of daylight each month - it's a kind of "sun strength" for the month, taking into account the maximum height the sun reaches in the sky, and the average cloud cover.

If the sun was at full summer height all day, and there was never any cloud cover, this graph would show the theoretical maximum of the array, which is 2 kWh per hour (or 2 kW as it should be called!)   At a smidge over 0.1 kW during December, the array is only producing 5% of its theoretical maximum. I am curious to see how high it will get over the summer months.

I've also submitted our Feed-in meter reading for the winter quarter (Dec-Feb) so I'll post again later in the month with a finances update.