Business case for a battery

[S2D2]

1 hour ago, Dillsue said:

If the Go rate disappeared I assume I'd be able to jump onto the Cosy rate if that wasn't withdrawn as well??

Yes if you have an EV and heat pump as mentioned. I switch between these two tariffs twice a year and it's within 24 hours now, often same day.

[Dillsue]

What's the rationale for switching between the tariffs?

[SteamyTea]

There is around 120 GWh of battery storage approved for the National Grid.

I do not know many domestic, or very small scale systems are connected, but suspect that it is a small fraction of that.

So when it comes to 'smoothing the grid', which will affect wholesale prices, the Big Boys are already on it.

So spend your money carefully and size any battery system to take best advantage of your own PV production.

Or treat it as a hobby, it is probably a cheaper one than most.

[Roger440]

1 hour ago, SteamyTea said:

There is around 120 GWh of battery storage approved for the National Grid.

I do not know many domestic, or very small scale systems are connected, but suspect that it is a small fraction of that.

So when it comes to 'smoothing the grid', which will affect wholesale prices, the Big Boys are already on it.

So spend your money carefully and size any battery system to take best advantage of your own PV production.

Or treat it as a hobby, it is probably a cheaper one than most.

 

Im inclined to think this is the most likely version of events, with its obvious effect in pricing.

 

I dont need another expensive hobby.

[Roger440]

7 hours ago, Dillsue said:

That's true, if the available surplus remained static which don't beleive is the case.

 

AFAIK there's still considerable wind power still to be installed to reduce the peak time reliance on gas. If that's the case then that wind power will need somewhere to go during off peak periods which could include any batteries I get:). Assuming I've not dropped a clanger in my calcs then what I have in mind will easily pay for itself in 3-4 years and it's a fair bet cheap TOU tariffs will last that long, if not much longer

 

Are you able to share that wheeze with us. That a very short payback. One i would consider.

[Dillsue]

57 minutes ago, Roger440 said:

 

Are you able to share that wheeze with us. That a very short payback. One i would consider.

Work out average daily consumption for each month. Put 20 units of each day or whatever the average is if its less than 20, into a battery at 8.5p=£1.70/day cost for 20 units to use during peak rate. At peak rate of 32p/unit the 20 units used during peak time would have cost £6.40 so there's £4.70/day saving. December's saving would be £4.70x31=£145.70. With my usage I'd get that Nov-Feb, a bit less Mar and Oct and quite a bit less for the summer when the HP isn't running and the PV is going full chat. Total for me is just under £1100/yr. 30kwh of Fogstar batteries and 6kw solis inverter is just under £4k. I'm also hoping to be increasing PV export by exporting most of what we currently use by using the battery and off peak eleccy rather than the PV. Not as lucrative as the peak to off peak saving but it's a bit more in the savings pot.

 

That's a rough estimate based on current Octopus Go rates and doesn't include charge/discharge losses. With 30kwh of batteries I think I'll be able to use more than 20kwh of off peak eleccy which will hopefully offset the system losses?? Figures pan out for me so just fine tuning things before taking the plunge

[S2D2]

4 hours ago, Dillsue said:

What's the rationale for switching between the tariffs?

In winter I need the 3 charging windows of cosy due to a small battery and big usage from the heat pump.

 

The other 9 months of the year solar replaces those charges and ASHP usage drops dramatically, so Go is cheaper for charging the EV and the battery once a day (8.5p/kWh vs ~14p/kWh).

 

If you do enough miles, it can make sense to stay on Go year round, so some due diligence is needed as my setup will not fit everyone.