Domestic batteries revisited

[DrFfybes]

But if the cost of batteries and panels come down, why should anyone include 'the grid'? A simple array of DIY solar panels and batteries serving your every need? Completely independent.

Steve

Cost.

We use 13kWh/day in winter. We would need about a 30kW array of panels to be sure of hitting our targets every day, or 20kW of panels and a 25kWh battery to last us a coupe of days. And a backup generator.

Last time I looked that was circa £20k, and between April and October the vast majority of energy generated would be wasted as it couldn't go anywhere once the batteries were full, which would be late morning.

Paul

[genou]

Last time I looked that was circa £20k, and between April and October the vast majority of energy generated would be wasted as it couldn't go anywhere once the batteries were full, which would be late morning.

Paul

Heated pool?

[DrFfybes]

A friend has just installed PV pretty much entirely for his heated pool.

I've had the first installer around earlier, so no quote yet, but as our roof has about 20 different slopes (lots of pointy dormers) the panels will be split over several faces, and he suggested 'optimisers' (I think) on each panel to help with monitoring. He also said he only uses Sharp or Huawei kit as some of the budget stuff has proved troublesome, but interestingly an extra 5kWh battery is about £2700 once the controller is in place.

This makes the maths far more compalling, in fact a 15kWh setup for under £10k would mean I could timeshift all our use to 8p/hour offpeak and save about £1200 pa, roughly 8 year payback.

The solar would all go to export at 15p, except perhaps in winter where it would be used to top the batteries up.

Again, I'm back to whether batteries make any sense with solar, and at the current solar export rates from Octopus I'm not seeing it. A 5kWh system is about £4200, and would just be enough to run the house overnight from about April until Sept/Oct at 15p rather than 33p, and it will smooth out the periods where the kettle/oven/immersion heater is using more than the solar generates at that point in time, but i'm only seeing £1 per day max saving for 6 months, so maybe £200 pa total, which makes a battery commercially a non starter.

Paul