EV Tariff with Home Battery

benjyminty

I have a 4.6kWh battery installed with solar panels. It has been recommended by the supplier that I charge this in the winter from the grid using cheap economy 7 electricity.
Bulb's (my supplier) EV tariff sells for 4p/unit from 2-6am. As their export rate for solar generation is 5.57p/unit, I cannot see a disadvantage of charging the battery from the grid all year round on the EV tariff.

Is there anything I've missed or need to consider?

benjyminty

NB do not own, or plan to own an EV

[Deleted User]

Bulb’s future for a start.

[Deleted User]

benjyminty said:

I have a 4.6kWh battery installed with solar panels. It has been recommended by the supplier that I charge this in the winter from the grid using cheap economy 7 electricity.
Bulb's (my supplier) EV tariff sells for 4p/unit from 2-6am. As their export rate for solar generation is 5.57p/unit, I cannot see a disadvantage of charging the battery from the grid all year round on the EV tariff.

Is there anything I've missed or need to consider?

Seriously, with a battery that size you need to calculate how much energy you will take from the Grid and the proportion that will be peak/off peak. It may well be that the peak price is as important as the offpeak price.

I have a 13.5kW battery so all my import (800kWhs/year) is offpeak. I am on Octopus Go so the peak price isn’t an issue for me.

Another thing to bear in mind is that your SEG payments are not protected by the Consumer Levy if your chosen supplier goes bust.

QrizB

So long as you're not going to be buying a huge amount of daytime electricity at 21.37p/kWh, it sounds like a reasonable plan.

At least while Bulb remain in business!

benjyminty

QrizB said:

So long as you're not going to be buying a huge amount of daytime electricity at 21.37p/kWh, it sounds like a reasonable plan.

At least while Bulb remain in business!

I don't think I will, there will be solar on most days, and washing etc can be timed to run off peak.
Octopus is a switching option, but will look at the details.

[Deleted User]

benjyminty said:

QrizB said:

So long as you're not going to be buying a huge amount of daytime electricity at 21.37p/kWh, it sounds like a reasonable plan.

At least while Bulb remain in business!

I don't think I will, there will be solar on most days, and washing etc can be timed to run off peak.
Octopus is a switching option, but will look at the details.

Octopus will offer you Go at 5p/kWH for 4 hours but their peak cost has risen by over 50% in a week. If you elect for Go, their SEG is reduced to 3p/kWh. For all other tariffs the SEG is either fixed at 5.5p/kWh or flexible if you are on Agile Outgoing.

benjyminty

Dolor said

I have a 13.5kW battery so all my import (800kWhs/year) is offpeak. I am on Octopus Go so the peak price isn’t an issue for me.

Can I ask why you chose 13.5kW? Do you have a gas supply? I'm trying to work out the best way of replacing my ageing gas boiler in my Victorian (single skin walls) house. Bigger batteries and night time charging might be an option.

[Deleted User]

benjyminty said:

Dolor said

I have a 13.5kW battery so all my import (800kWhs/year) is offpeak. I am on Octopus Go so the peak price isn’t an issue for me.

Can I ask why you chose 13.5kW? Do you have a gas supply? I'm trying to work out the best way of replacing my ageing gas boiler in my Victorian (single skin walls) house. Bigger batteries and night time charging might be an option.

A number of reasons. One, it provides me with cheap power throughout the Winter at 5p/kWh for anything taken from the Grid. Two, it provides me with power up to 5kWs if the Grid goes off. Three, it enables me to charge my EV when there is very little solar surplus. For example, it is very cloudy at the moment with a total output of 1kW of which 300Ws is max house baseload. The minimum charge rate for all EVs is 1.3kWs so if I turn on my charger to its Eco setting it will charge at 1.3kWs with 1kW coming from excess solar and 300Ws from the battery.

In my opinion, there are a number of factors that need to be considered before getting rid of a gas boiler. Not least, that the sun doesn't shine that much in Winter and that I can well see offpeak prices increasing as demand increases. You would also need at least two Powerwall 2s to run heating effectively off Grid: that might require you to install a 3 phase supply. Finally, the RoI on batteries is such that there is only a reasonable payback with a large solar array (I have 7kWp: I wish that I space for more.)