I have a modest set of solar panels on an entirely ordinary house in suburban London. On average they generate about 3,800kWh per year. We also use about 3,800kWh of electricity each year. Obviously, we can't use all the power produced over summer and we need to buy power in winter. So here's my question: How big a battery would we need in order to be completely self-sufficient? Background …
I looked into one of these thermal systems for my own place but the outlay is just massive for the 11 weeks months a year I really need heat, and the rest of the year it’s just a stupidly oversized hot water heater that is cooking my glycol and DC pumps.
I ended up paneling up and putting a dumb 9kw resistive boiler for my hydronic floors. The house slab is the battery and although inefficient in terms of strict energy efficiency, winter sun on my cheap pallet of panels dumps plenty into the resistance coils all day. I do have to light the stove if we get a snow storm for a day or two though
Yes. Hydronic flooring is cheap at construction time. Complicated if drilling into finished ceilings/floor with thicker under floor space making. But instead of 9kw of winter electricity you are forced to import, it is free fall surplus generation. 100w of pump circulation.
But you are saying, a resistive boiler made more sense than a heat pump, with the hydronic floor conversion. At first I thought you were just saying resistive heating electric floor. The latter, to me, would be the cheapest capital outlay conversion, and then a heat pump would beat a resistive boiler on operation costs if hydronic.
Yeah I already had the hydronic floors and ran numbers on heating the floors off thermal solar panels, propane, heat pump, and the resistive boiler. The thermal panels made the least sense because they are useless eight months of the year.
The heat pump might have worked but when I really needed it my semi-outdoor closet would be in single digits and full of water supply pipes so the heat pump would be least efficient when I needed it most, and would not help keep the closet warm.
The resistive boiler meant I could add a bunch of panels to run it during the day and get the floors up to 85F, then run all electric appliances with no worries during the day the rest of the year with the extra capacity. So instead of being net positive generation from 10am to 4pm in summer, its now 8 am to 6pm with way more than I can use at peak.
I looked into one of these thermal systems for my own place but the outlay is just massive for the 11 weeks months a year I really need heat, and the rest of the year it’s just a stupidly oversized hot water heater that is cooking my glycol and DC pumps.
I ended up paneling up and putting a dumb 9kw resistive boiler for my hydronic floors. The house slab is the battery and although inefficient in terms of strict energy efficiency, winter sun on my cheap pallet of panels dumps plenty into the resistance coils all day. I do have to light the stove if we get a snow storm for a day or two though
Yes. Hydronic flooring is cheap at construction time. Complicated if drilling into finished ceilings/floor with thicker under floor space making. But instead of 9kw of winter electricity you are forced to import, it is free fall surplus generation. 100w of pump circulation.
But you are saying, a resistive boiler made more sense than a heat pump, with the hydronic floor conversion. At first I thought you were just saying resistive heating electric floor. The latter, to me, would be the cheapest capital outlay conversion, and then a heat pump would beat a resistive boiler on operation costs if hydronic.
Did you investigate all of these alternatives?
Yeah I already had the hydronic floors and ran numbers on heating the floors off thermal solar panels, propane, heat pump, and the resistive boiler. The thermal panels made the least sense because they are useless eight months of the year.
The heat pump might have worked but when I really needed it my semi-outdoor closet would be in single digits and full of water supply pipes so the heat pump would be least efficient when I needed it most, and would not help keep the closet warm.
The resistive boiler meant I could add a bunch of panels to run it during the day and get the floors up to 85F, then run all electric appliances with no worries during the day the rest of the year with the extra capacity. So instead of being net positive generation from 10am to 4pm in summer, its now 8 am to 6pm with way more than I can use at peak.