Solar + Battery evangelist, plus a thank you

We have had solar since 2018 and it’s always been good but sending so much to the grid felt like we weren’t making the most of it.

I’d had my eye on batteries for a while but the cost vs warranty didn’t seem to make sense at the time, obviously current electricity costs would change that equation. We were lucky enough to get on an Ovo scheme to test 5kWh home batteries, a massive thank you to the PowerShaper team who advertised the opportunity.

We had it installed in August/September but was hard to tell how much it was working at the time, as solar is also reducing as Autumn comes round.

We’re a family of four and have an EV and all our cooking is electric, so our bills are quite high; in winter with no solar we can pay over £200/m just on electricity (and that’s prior to the current crazy price hikes).

This spring, I’ve been blown away by how well the battery works, from March onwards we were getting enough sunshine to fully charge it, and if we’re careful 5kWh will see us through from sunset to sunrise. We’ve had our first couple of bills now and we’re averaging about 7kWh of grid usage a day, or 200kWh per month, this works out as £40 on electricity (including standing charge) per month. Our overall usage is around 500kWh including solar.

£40 is pretty phenomenal when it also covers all our driving for the month! So, a big thank you to the Carbon Coop team for pointing us in the right direction, I owe you some drinks, and we’ll definitely be looking to increase the size of our battery to nearer 10kWh so we can use more of our solar in the summer plus off-peak electricity in the winter.


I would also like to increase my battery capacity but it is difficult to justify, as the extra capacity will only be needed on infrequent occasions, unlike the current battery which is being used to the maximum almost daily.

Yep there’s definitely a balance to find, I guess it depends on how variable your load and your generation is!

Which battery system have you got and what size battery?


We bit the bullet as part of a needed renovation of our conservatory/dining room roof in December, went for in-roof solar (supplementing our 11 year old 3.3 kWp arraywith a further 3.1kWp) and a Powerwall. It was the thick end of £20k :exploding_head:. However we have electric heating (air source heat pump) as well as an EV, so wanted to minimise our exposure to rising prices. Like you, we are feeling smug now; last month’s total gas and electricity bill (April) was £36, with the standing charge being 35% of that.
My analysis is that most households will do well with a 5kWh battery (cf our 13kWh), however electric heating pushes means nearer 10kWh is better and we also needed a 5kW inverter (most smaller systems are only 3kW) to drive the heat pump.

We are now seriousy considering removing gas entirely. Once I can afford a Sunamp thermal battery to supply hot water (we have no hot water tank at present) then we will do that.

Even with the big battery, we exported hundreds of kW hours last month!

Sounds like a phenomenal system, what in-roof solar system did you use? I’m looking at options for our extension, adding solar to another roof face as part of the renovation.

Sorry to be so tardy in responding.
Ours is a Viridian Fusion array comprising 9 x PV16-G1 panels 335W, mated to a Solar Edge SE3000H inverter (3kW).

Despite the oblique angle of incidence our roof structure mandates we have doubled our solar generation.

Hi Simon, are you able to recommend the installers, ref the PV? I am enquiring for a neighbour.
Thanks Julian
PS we exchanged messages about the BUS and you mentioned selling old boilers - I sold mine on eBay for what I thought was a fair price.

I routinely recommend all these folk

Oval Renewables
07590 683401

East Riding Energy


What was the fair price you got, to set my expectations?

Thanks for the recommendations Simon
The boiler sold for £375 on eBay