Geeking It Up – Solar/Battery System

Last year, I decided to get a home battery system. According to Octopus Energy, my supplier, I use about 7-13kWh of electricity a day, excluding the electricity used to charge my car.

I am on the Intelligent Octopus Go Tariff. My day-time electricity costs just under 30p/kWh, but between 11:30pm and 5:30pm it drops to just 7.5p/kWh (Intelligent also includes some bonus charging, but let’s ignore that).

I use the cheap tariff for charging my car, and also running the washing machine and dishwasher.

My plan was to get a 10kWh battery, this being my average usage. This means I could charge the battery at night, at 7.5p, to use it during the day, thus moving almost all of my usage onto cheap rate. This could save me about £8-900 a year, and pay off the £6,000 cost in about 7 years.

Then I hit a snag. The cost was going to be £7,200, because back in 2023, if you bought battery without solar, you were charged VAT at 20%.

I then asked for a quote for the battery + “minimal solar” – enough to get rid of my VAT. The smallest installation that my local (well-recommended) installer would do was 3 panels. This brought the total cost up to a surprising number – £7,200. The cost of the panels, and installation, was the same as the VAT I would have to pay on the batteries alone. So a no-brainer. But I also asked them to quote for a full 8 panels (one half of my roof). That only came to £9,000. Because, of course, once you have scaffolding and wiring up there, adding a few more panels is relatively inexpensive.

So I went for that solution – 8 x 410W solar panels, a 9.5kW GivEnergy battery, and a GivEnergy hybrid inverter.

We set it up for installation in January/February. Irony of ironies, in February, the government U-turned and scrapped VAT on battery only installations. I decided to go ahead with the full solution, anyway.

This week, it all happened. The scaffolding went up on Monday, work started on Tuesday. It was scheduled to be a two day install, but the guys are local, it was a beautiful day, and they managed it in one day, with one guy popping in for an hour on Wednesday to added some wire clamps to the wall.

The solar panels are on the front of the house. I chose this for two reasons:

• The conservatory at the back might have made scaffolding interesting.

• The front of the house is SWW facing. I figured I could charge from the cheap tariff overnight, then top up when the sun came round the front.

But it seems I underestimated the ability of the panels, as I am getting steady power off them even before the sun creeps round. This is all good, because Octopus also has some decent Export tariffs, which I can take advantage of.

The battery and inverter can be mounted outside, with a shelter.

But I have decided to install them in my box room.

As you can see, it is all very neat, and once I put everything back in the room that belongs there, it will be out of the way, but accessible.

I am really pleased with the system, which is already outperforming my expectations. I’ll post about that, at a later date.

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