[No longer] Going for a Givenergy 8.2 kWh AC Coupled battery

Petriix

With the crazy prices, I've done my man-maths, made a spreadsheet, and decided to get a Givenergy 8.2kwh AC coupled battery installed. If anyone has this system and wants to share their thoughts before I commit, please chime in!

The price is a little under £4k from a company called CRC Electrical and Renewables. If anyone has any experience of them then let me know your thoughts; they have a bunch of favourable reviews and seem totally legitimate.

With optimal usage I can save over £500 per year compared to the current price cap. Octopus Go wouldn't save me much without the battery because I have a fair amount of unavoidable peak usage. If prices rise in April as projected then the ROI could be under 4 years.

pete-20-11

Do you have an EV? 

Will Octopus allow you to renew Go without one? 

Petriix

pete-20-11 said:

Do you have an EV? 

Will Octopus allow you to renew Go without one? 

Yes, I have an EV. Octopus told me that they would accept me as a new customer (was with Symbio then Neon Reef RIP).

Laycity

I presume you haven’t got solar? The maths is starting to make sense though for battery only installs, especially if you start using 25 - 30p per kWh rates in your calculations. 

A friend of mine has Givenergy batteries with solar, his installer couldn’t get hold of the 8.2kW (was in early summer, but check that they can get hold of them) so had to go for two 5kWs instead.

Check the actual usable kW of the battery and the peak rate that it can supply which are important if you are looking at payback times.

Also there are rumours that Octopus Go is for EV users only for new applicants and the tariff may not be around for ever, there are other economy tariffs available of course. 

Petriix

Laycity said:

I presume you haven’t got solar? The maths is starting to make sense though for battery only installs, especially if you start using 25 - 30p per kWh rates in your calculations. 

A friend of mine has Givenergy batteries with solar, his installer couldn’t get hold of the 8.2kW (was in early summer, but check that they can get hold of them) so had to go for two 5kWs instead.

Check the actual usable kW of the battery and the peak rate that it can supply which are important if you are looking at payback times.

Also there are rumours that Octopus Go is for EV users only for new applicants and the tariff may not be around for ever, there are other economy tariffs available of course. 

I do have solar (3.42kWp, south facing). I currently manage to use about 55% of what I generate (1856kWh of 3180kWh so far this year). I think I could get close to 90% with optimal use of a battery because I tend to leave the car plugged in on the Zappi most days, waiting for surplus. I can actually use the battery to make up the small shortfall when charging mostly from solar when there's less than 1.4kW of surplus.

2nd_time_buyer

Have you factored in the roundtrip losses?

For solar energy stored and going back to the grid, there would be losses for-

-DC (solar) to AC inverter

-AC to DC charge inverter
-Battery charging

-Battery discharging 

-DC to AC (grid) 

I am genuinely not sure what the total of that lot is but I wouldn't be surprised if it was upwards of 20%

Petriix

2nd_time_buyer said:

Have you factored in the roundtrip losses?

For solar energy stored and going back to the grid, there would be losses for-

-DC (solar) to AC inverter

-AC to DC charge inverter
-Battery charging

-Battery discharging 

-DC to AC (grid) 

I am genuinely not sure what the total of that lot is but I wouldn't be surprised if it was upwards of 20%

Yes, the great thing is that the losses pre-battery are not much of an issue: the solar would be exported for no particular gain to me (I'm on deemed export payments) and I'll only ever be charging from the grid at 5p overnight, so a ~15% loss equates to 0.75p per kWh.

On the way out of the battery the losses are more painful because they directly reduce the effective useable capacity. 15% losses, worst case I'm down to 5.5kWh useable. That's still going to comfortably cover my background usage, cooking dinner, evening AV equipment and lighting etc.

I should be able to reduce my peak imports to almost zero. That way, the ~ 2500kWh I'll be importing will all be at 5p so about £125 for the year. Quite a difference from importing 1000kWh at 5p and 2500kWh at 25p. That's a £550 saving.

These are optimal numbers and it may well not quite work as well as that. However, it also discounts the possibility of enormous price increases, which look to be coming in April. 

Spies

Couldn't you sell your current inverter and swap it with a hybrid one?

Petriix

Spies said:

Couldn't you sell your current inverter and swap it with a hybrid one?

A hybrid inverter would be a disaster for someone like me with FIT and deemed export payments. It's far better to swallow the extra losses from converting back to DC.

The alternative (with a hybrid inverter) is a complicated dual meter setup where you record how much grid energy goes into the battery and deduct that from your FIT readings. I'm not sure how easy it would be to explain to my current (or any future) FIT provider, and all losses from the AC-DC conversion would act to reduce my FIT and export payments. 

Spies

Fair enough, hadn't thought about FIT payments!

Swan_Valley

We have 2 GivEnergy 8.2kWh batteries (recently installed as we had to wait months for them to be available).

Very happy with them, the App & the web portal.

We are using them to power our 2 A2A ASHP throughout the day, to avoid using GCH.

Charging them up overnight on 5p/kWh & top up during the day from excess solar.