For most months here grid usage averages less than 1kWh/day
at the supplier's daytime Standard Rate thanks to their alternating 12 hour split rate tariff similar to the EdF 20/20
one. Most usage is at a 20% discount ‘off peak’ rate. This exploits the way that solar usage displaces daytime grid use, and this overall saves us here 15% of the 'leccy bill
It would be very similar for the other months too if the solar was facing south-ish like so many other Microgeners. (It is only due to the East-West orientation plus some autumn and spring shading that there is any significant daytime ‘standard rate’ grid usage between October and February.) Amongst the benefits of having Solar PV, I consequently rank the opportunity of exploiting such a split rate tariff as pretty high.
We use gas for cooking, and have LED lighting (hence why the 20% discount-rate usage is also low). Overall we are slightly below-average users of about 3200kWh/year shown here comprising
- 12%, 390kWh/year at standard-rate,
- 34%, 1120kWh/year solar, and
- 54%, 1680kWh/year at 20% discount-rate.
The figures are all from a Smart Meter, with the ‘solar usage’ element being generation minus the Export recorded on the Smart Meter.
There are commonly also “Economy 10” tariffs like SSEs Powerfuel
that give a 40% discount for 10 off-peak hours a day, which may be even better for south-facing rooftop solar households. A south-facing installation might benefit even more from a tariff with a higher discount that does not cover all the weekend. Here though, there is a combination of low winter solar generation and weekend household consumption to consider.
(N.B. There are some peculiarities to my standard-solar-discount breakdown chart.
(i) March 16th was when the Central Heating was turned off in favour of the lounge gas fire plus storage heater for a month,
(ii) the high usage December 26th to January 2nd period was when the whole household was at home, and
(iii) we were away during the summer solstice period, which would normally and otherwise have been the period of highest solar usage.)