Cost of going completely off grid for power

MouldyOldDough

MattMattMattUK said:

MouldyOldDough said:

I have seen a US based estimate of 800kWh per month average useage of electrical power - I currently use 120kWh electricity (winter) !

US usage is always insanely high, but does yours also account for an alternative source of heat such as gas, or is 120kWh your entire domestic energy consumption? 

We also use on average 350kWh gas monthly (winter) and 150kWh summer

[Deleted User]

MouldyOldDough said:

I have seen a US based estimate of 800kWh per month average useage of electrical power - I currently use 120kWh electricity (winter) !

Two things to think about. A battery stores electricity in kWh: your devices use energy in kW. My Powerwall 2 will store 13.5kWh of electricity but it will only discharge it at a maximum of 5kW. 5kW may be enough to run your heat pump for a couple of hours but not your heat pump and a kettle.

I confess that I have no idea how many kWh a heat pump would require on a cold Winter’s Day but I suspect that it is a lot more than 13kWh.  I should add that to get 9kWh from your roof via your battery to your home requires up to 10.5kWh of solar due to transmission losses.

QrizB

[Deleted User] said:

I confess that I have no idea how many kWh a heat pump would require on a cold Winter’s Day but I suspect that it is a lot more than 13kWh.

MouldyOldDough states:

MouldyOldDough said:

We also use on average 350kWh gas monthly (winter) and 150kWh summer

That's an unusually low amount of gas; barely 10kWh/day in winter, which might be due to their thermostat being set to 14C which is also unusually low.

If they only need 10kWh of gas a day to heat their home I can't see the cost of a whole-house heat pump being justified; direct electric heating would be a better option.

Verdigris

The 50p a day to use the grid is considerably less than the interest you'd pay on several hundred thousand pounds worth of generating and storage kit.

With a reasonably large solar array, say 10kWp, a 20kWh battery, a share in a windfarm to produce 3 or 4000kWh, you might be able to run a house with heat pump, charge cars in the summer months and have a couple of days protection from power cuts for essential electrical use (not heating - you'd need a back-up such a wood-burner). However to achieve this you'd need to import and export via the grid, which would require an account with a somebody like Octopus, and a smart meter, to ensure a supply at all times.

Call it Schrodinger's supply - you be on the grid and off the grid at the same time. More importantly you have lights a heating all the time with minimal carbon outputs.