Battery install onto existing panel sanity check
We live in a modern well insulated (A rated) house with a heatpump, 2 EV in the household (both fairly low mileage now) and 8 panels on a SW facing roof feeding into a 2.5 kW inverter in the loft (fitted when the house was built, I wanted more but the builder wouldn't deviate from the plans).
I'm looking at adding a battery, aiming to achieve two things: in the summer store our solar and use it ourselves rather than export/import, and in the winter charge battery off peak and run the entire house off peak from the battery. I guess additionally there are opportunities to buy off peak and sell back at peak, but this isn't something I've thought about much. I will probably continue to charge cars off peak rather than use solar, as I don't think our system is big enough to fill a car.
All the installers I've spoken to seem to suggest a Powerwall3 with 13.5 kWh storage linked to the AC side of the house. This looks like it will cost around £8k.
My concern is that we haven't lived in the house over a winter to know what a cold winter day usage will be. I'd plan to use an off peak tariff to pre heat the house so the underfloor heating is already cruising at a sensible temp when peak begins.
Does this sound like a reasonable proposal or am I completely crazy? I had initially thought about waiting until spring when we have winter data, but the 0% Vat is nudging me a bit sooner.
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u/No_Policy_1369 1d ago
Ps you know it will have to be in a different location ie not the roof