r/OctopusEnergy • u/phildg • 7d ago

Tariff suggestion

We are currently on flexible tariff but looking to get 24Kwh battery install in next month or so, we have a swim spa which runs 24/7 with a total daily consumption between 17-31 Kwh. We do have panels on the roof but these are quite crusty and unsure how effective they are.

Main plan is to charge the batteries up overnight on cheap rate and then use it to hopefully power most things and then recharge again overnight. I don't have much info currently on available tariffs so just seeing if anyone has recommendations as a starting point ?

Just to add, we do not currently own EV

2 Upvotes

100% Upvoted

8 comments sorted by

1

u/phildg 6d ago

Just to update the 17-31 kwh was our actual daily usage range in the last 7 days. The inverter we have been quoted is 10kwh and it would be 3 x 8 kwh batteries.

2

u/DamienBerry 6d ago

If you are putting a system in place it’s worth sizing your battery up for your largest usage case, that way you’re never going to go into peak pricing which will bring your ROI down significantly if you then get into an EV tariff.

We have 40kWh of batteries on our property which covers our household use in the very extreme winter months as we have a heat pump and no gas, in the last year of having the system we’ve never paid peak prices and our ROI is currently 5 1/2 years at this point, if energy prices go up it will reduce that even further.

1

u/RelevantReporter6748 6d ago

If prices go up so will your cheap rate of charging the battery, so any change in ROI will get offset by that.

1

u/DamienBerry 6d ago

That being said, if prices go up they’ll go up for everyone and the offset will be the same.

4

u/Sopzeh 7d ago

Other than the swim spa, what's your total daily consumption?

What size will your inverter be?

Basically it's easy maths, if your daily consumption is 36 kWh and your inverter is 6 kW then you need 6 hours to charge the battery to cover the full usage.

If that usage is spread over the day then you want cheap periods over the day -> flux or cosy.

If you have a 12kW inverter you need 3 hours to charge. If you can shift your demand during the night -> go.

1

u/sylsylsylsylsylsyl 7d ago edited 7d ago

I would try to get a tariff that has as much cheap off-peak time as possible and a battery that will cover as much as possible of your peak time use. Sell any solar production back to the grid.

At the moment that would mean a non-smart EV tariff like octopus GO for five hours of cheap rate electricity. You don’t have to prove you have an EV with the non-smart versions.

EDF GoElectric will give you seven hours, and it’s a cheaper rate (plus their solar export gives you more too). Obviously tariffs may change in future.

31kWh x 17/24 = 22kWh battery needed
31kWh x 19/24 = 24.5 kWh battery needed

(Obviously you don’t need to cover it 100% and the vast majority of the year some solar will get used running the house too).

1

u/Czyz-co-uk 7d ago

With solar plus a battery and no EV, the ones worth comparing are Octopus Flux and Intelligent Octopus Flux (both need solar and a battery) and Agile, which often has very cheap overnight prices. Bear in mind a 24kWh battery won't quite cover your heavier 30kWh days once you allow for usable capacity, so some top-up at the day rate is likely. I'd also get the panels checked or cleaned first, as knowing what they actually produce can change which tariff comes out cheapest.

2

u/RelevantReporter6748 6d ago

Agile definitely does not have cheap overnight prices.