Tesla is testing technology where you can plug your car in and have the car power the house overnight then charge in the the day when you have excess solar production. I would never suggest buying a Tesla but the technology sounds like a good idea and in 5-10 years it might be available across a wide range of cars.

The Ford Lightning does that, too, without having to support the Muskrat. But a vehicle that new would be pretty far outside the budget right now.

Anyway, you’ve got me a bit curious now about the possibility of finding an EV battery in a junkyard and maybe using that as solar battery storage. Though … those usually run at pretty high voltages. Finding both charge controllers and inverters capable of dealing with those voltages might be difficult and expensive enough to negate any possible cost savings on the battery itself. Plus, then I’d be kind of locked into that type of battery when the time eventually comes to replace it, since that high voltage equipment probably won’t easily convert to a more usual 48V system.

Depending on climate (I keep saying that as I don’t want to be responsible for you freezing to death)

Don’t worry, we’re hardy folk! Having parts of the house freeze over is actually kind of routine for us at this point. We only heat small rooms within the house, and through much trial and error, we’ve found freeze-resistant plumbing options. (We used to have basement floods every winter, but now we’ve converted the whole house to pex plumbing, which turns out to have good freeze resistance. Copper always developed cracks or pinhole leaks, steel would always burst a fitting, PVC would absolutely shatter, but pex has enough flex to it that it has been able to survive a few good freezing events without causing any leaks – just a temporary lack of water. And in those temporary freeze-ups, we have an outdoor frost-free faucet run directly off the supply line that always works, and we can fill from that for a day or two until the cold snap ends and the plumbing gets above freezing again.)

And there’s always the backup generator, which will cost a fortune to run, but will prevent anybody freezing.

Though it may worry you even more, I actually think I’m planning on putting that backup generator in the basement (with tightly sealed and double-wrapped exhaust pipe running outside, air intake routed from outside, a remote shutoff switch, and a dozen carbon monoxide alarms scattered around, of course!) But the advantage there (besides not needing to build and outdoor weatherproofing enclosure for it) is that most of the generator’s waste heat would then help heat the house, at least enough to keep the basement above freezing and keep most of the pipes from freezing. Since most of the times we’d need a generator are when it’s very cold, that could actually make it way more efficient, since most of its energy would be used for heating anyway.

just that you need that water stored inside, and one day (whether next year or in 30 years) they will rust through and make a big mess!

Don’t worry about that, they’re plastic drums. The biggest concern would be that they might at some point freeze and burst … but that would never happen if I fill them with an antifreeze solution. The real biggest concern is just how much space they would take up … and possibly how much weight they’d be adding to the floors.

Inverters tend to only handle 10kWh production at a time (with short term spikes above that)

Yeah, may end up having multiple charge controllers in addition to the inverter’s built-in solar charge controller(s).

Personally, I’d prefer to have those systems be entirely separate in the first place, so each one can be sized according to need and each one can be independently replaced if it breaks. But it seems that most inverters capable of handling our ~6.2kw absolute peak usage already come as ‘all in one’ inverters with solar charge controllers built in … I guess I might as well use the built-in charge controller, at least for part of the solar array.

It’s hard to imagine 2 people using more than that outside of very specific events

Yeah. Honestly, I have no idea how we ever got up to 6.2kw that one time… Our average usage never even gets close to 2kw. We’d definitely have to be running the oven at full blast, probably and a couple stove burners, and possibly the microwave/tea kettle at the same time … and probably some other big loads to even get that high.

But the nice thing about having all this data to look at is being able to see that those peak usages are very rare. Out of ~51,000 five minute data points, only 70 five minute segments had usage above 4kw, and never more than about 15 minutes in a row.

Even if we changed absolutely nothing about our usage, if we built the system to be capable of providing 4kw reliably, we’d only need to use the generator ~6 hours per year.

And, honestly, It just has to be a massive cooking task contributing to those absolute peak usage moments. Nothing else we have could possibly come close to using that much power. If we simply avoid using the stove/oven at night in the winter, that’s probably enough to drastically reduce our peak demand and significantly reduce our need for battery capacity.

Right, I’ll find that solar generation data and send it through.

Thanks!