Solar Update – Solar Export Guarantee

We have had the solar PV system in now for over 3 months so I thought I’d do a quick update on how it is going.

Pretty well actually! As you can imagine, it is winter so there hasn’t been many good solar generating days since installation and when it was sunny the sun is very low and only up for a few hours each day so this is not the time to properly assess the potential. However, the results so far are very promising.

The system has generated 645 kWh since the end of September and that is through winter and the darkest days. Our best day was just a few days ago at 15.4 kWh in the day. Even with the sun still low and not very strong this is making a huge difference to our electricity bill.

Take today… this is the stats directly from the inverter…

This shows that we used in the house 15.82 kWh today but because we managed to use some of our solar we only imported (bought) 11.48 kWh. We generated 14.63 kWh but of all that we generated we only managed to use 4.33 kWh of that ourselves… the remaining 10.3 kWh we exported to the grid.

So how has that effected our bill?

Well, without solar PV we would have paid for what we used… 15.82 kWh and at 15p/kWh that would have been a bill for today of £2.37.

Instead… we only imported 11.48 kWh so the bill was only £1.72. Moreover, we exported 10.3 kWh of unused solar for which we get paid 5p/kWh under the new Solar Export Guarantee (SEG) so we get back 51p making our total bill for today £1.21… a saving of £1.16.

When you consider that this is still very much winter I don’t consider that at all bad. Once we get into summer I am sure that our daily bill might even go negative… that is we export enough for the export payments to cover the cost of what we have to import.

For example… if we generate say, 30 kWh and export 20 kWh of that (i.e. we use 10 kWh ourselves with 6 kWh imported – assuming a similar use pattern – no reason to see it very different as our summer to winter use is very similar for electricity) then we will have a import bill for 6 kWh of about 90p and an export refund for 20 kWh exported of £1.00. This means no electricity bill for that day and an extra 10p towards the daily standing charge!

This is by no means an unlikely scenario.

The issue for us then is how much would a storage battery add to the mix? A battery is going to cost over £4000 (for 10 kWh storage) so if we cannot use all the power stored in the summer then will it be financially worthwhile installing a battery? I haven’t done the sums yet but the fact that I can earn 5p/kWh to export it has to cast a doubt. I shall report back once I have looked at the figures at the end of March.

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