ectoplasmosis-
Key information for 2023 (6.6kw solar, 13.8kw battery):
Generated 5840kw
Exported 2290kw
Purchased 3596kw
Total electricity consumption 7146kwAverage octopus tracker tariff price was 19.64p/kw with a standing daily charge of 47.5p
Export price was 15p/kw
Purchased electricity - £706.25 + £173 = £879.25
Exported electricity - £343.50
Our electricity bill was £535.75 last year.If we didn't have solar, our bill would have been £1576.47, so solar has saved us £1040.72.
We spent approx. £17500 on the solar and battery setup so it would take an unimpressive 16.8 years to pay it back. This is partly because of the drop in electricity prices, at the time we were facing 40p/kw or more, at this rate (which will surely happen with inflation going forwards) we would be saving £2323 per year, and solar setup would break even in 7.5 years.
Thats not using the EV fuel savings (the cost of leasing the cars/insurance have remained approx the same when switching from petrol to EV).
We will use approx. 5714kw for charging the EVs (about 20k miles) which will cost us £428 per year.
Equivalent petrol at 150p/l and 40mpg is £2838 per year.
Saving of £2410 per year on fuel.£3450 saved per year, just over 5y to pay back the system.
As we have changed how the system exports and imports electricity, and have a second EV I expect our usage to look like this:
4500kw home use at 7.5p (charged overnight and used during the day via battery)
5714kw car use at 7.5p
Total: £766.05 + £173 standing charge = £939.05
5800kw solar export export 15p = £870
Electricity + fuel bill of £69 for the year.No solar EV comparison:
Electricity bill of £1065 (assuming 19.64p/kw)
Petrol bill of £2838
Total bill of £3903 for the yearSaving of £3834 per year
Pay back the system in 4.56y, faster as petrol and energy prices increase over time.
At the time we decided on switching to solar, battery and EV, electricity was 40p/kw and petrol was 180p/l. If it had continued in this way, we would have had the total system paid back in 3.4y.A big bulk of the benefit is the EV fuel saving, and the battery, which then allows the 7.5p intelligent tariff and usage.
A 10kw battery, say for £5000 installed (currently 0% vat) charging at night, 4000kw annual usage. If you had 1 EV using 2800kw (approx. 10k miles) and you charged at night at 7.5p.
£510 electricity a year.
Compared to 10k in a petrol car, and 4000kw at 19.64p/kw, you would save about £1700 a year, paying back the battery in under 3 years. Without an EV, battery would take 10 years to pay back.Obviously continued significant savings after that period.
TLDR:
Even though we spent more than needed for the best return on investment, we should pay the system off in under 5 years, and saving ourselves about £3000 a year thereafter.
Buy as much as possible cheap at 7.5p, sell everything you can at 15p or more.
Petrol is expensive.
You are reading a single comment by @ectoplasmosis and its replies.
Click here to read the full conversation.
Acliff
I have 6.6kw of solar panels, split east and west, with a Tesla powerwall.
2 EVs, being charged overnight on the intelligent go 7.5p tariff and being paid 15p export on solar.
We’ve set it up to never charge the battery using solar and to export every Kw to the grid, and the powerwall has enough storage to sort us out through 5am-1am.