Economy 7 rates and battery charge.
Posted: Thu Nov 12, 2026 7:55 am
Just wondering how others operate their charging schedules through winter.
My E7 rates are ~14p for cheap rate and ~32.5p for day rate with export at 14p.
I was going to try and second guess my daily generation and adjust my charge schedules accordingly but have come to the conclusion that unless I'm pretty much spot on each day, I'm better off doing a full charge.
1. If I fully charge my battery from empty, it will cost ~ 77p (including losses). If it turns out I needed none of that due to solar gen meeting demand, I will export about 5KW= 60p. Loss for the day = 17p.
2.If I don't charge my battery enough and it turns out I need to import from grid, my loss would be 14-32.5 = 18.5p per KW needed.
The first scenario can never be exceeded so can only ever cost 17p per day whereas if I'm totally out on the second, it could be multiples of 18.5 although I also accept it could be less if I second guess accurately enough.
Because scenario 1 will rarely be a full error of judgement its more likely to only cost say 12p a day at worst which means I'd need to charge accurately to within about 0.6KW if trying to second guess my generation. I think that is more effort than its worth.
What do others think.
My E7 rates are ~14p for cheap rate and ~32.5p for day rate with export at 14p.
I was going to try and second guess my daily generation and adjust my charge schedules accordingly but have come to the conclusion that unless I'm pretty much spot on each day, I'm better off doing a full charge.
1. If I fully charge my battery from empty, it will cost ~ 77p (including losses). If it turns out I needed none of that due to solar gen meeting demand, I will export about 5KW= 60p. Loss for the day = 17p.
2.If I don't charge my battery enough and it turns out I need to import from grid, my loss would be 14-32.5 = 18.5p per KW needed.
The first scenario can never be exceeded so can only ever cost 17p per day whereas if I'm totally out on the second, it could be multiples of 18.5 although I also accept it could be less if I second guess accurately enough.
Because scenario 1 will rarely be a full error of judgement its more likely to only cost say 12p a day at worst which means I'd need to charge accurately to within about 0.6KW if trying to second guess my generation. I think that is more effort than its worth.
What do others think.