Building my own solar power system

If your electrical installation allows it: You can connect your ev plug before the battery so that it does not drain the battery. You can do this by placing the fuse/connection before the measurement clamps for the battery. Somewhere in between your mains connection and your battery/solar system.

This way the battery does not see the load and does not provide power to your EV.

That way you can still use excess solar (before you inject it into the mains) to charge your car + you do not pull power from your battery :)

Midnight Solar are the OG company in off grid and they have a "waste not" feature from way back that triggers any device when the parameters you set are reached, ie: float voltage, and/or other things, like a second set point where power would be sent to a third load, like the grid or water heating. https://www.midnitesolar.com/ hard core techies, even had the pleasure of detailing my inadvertant and unsucessfull attempts to melt one of there controlers.......literaly had a main lug get loose, and the panels arc melted the lug to slag, and it lived. in any case, there web site has a wealth of info on what is possible, and to look for elsewhere

What do you do with that much electricity? Was it necessary to over-dimension for winter?

Well problem in the UK is that in summer there is like a magnitude more power from PV then in winter.

One of those areas where policy action is desperately needed but no attention is paid due to media dysfunction. I think the UK would benefit from region-specific pricing, to move the datacenters closer to generation rather than urban environments. It would also encourage more embedded generation in expensive areas.

Add smart storage and demand response, and you've basically got a decentralized resilience network

Batteries are dropping fast in price, but for the USA, they might be going up because of tariffs. Neatly sidestepping that:

I have a powerwall 2 with 5kw panels, which I've had since about 2021. At the time it was the biggest, cheapest, had a grid isolation mode, and could be mounted outside. (I didn't trust tesla back then, and I sure as shit don't now. Moreover, once it catches fire, that shit aint going out anytime soon)

It still cost about £7k installed.

From about march/april to end of october, we are power sufficient (london, even with rainy days, gas hot water though.)

If I were to get a new system, 13kwhr of battery is something like £2k, plus inverter/charger.

The panels are dirt cheap, to the point where the scaffolding costs more than the panels. (and the mounts.)

Crazy stuff. Ten years ago I paid £5.5k GBP for a 3.7kW system. Since then I would expect the labour component to have gone up but the panels to have come down. I guess the skilled labour shortage in the US is having a very real effect on prices.

Under the subsidy rules for feed-in-tariffs at the time, that had to be done with an MCS approved installer. All work in England would require an approved "Part P" signoff anyway. However it did not require council planning approva, nor grid approval for that size of system.

I see 7k€ for 12kWp, retail, for a diy ground install set for our summer house. That's before 4k€ in subsidies. No net metering, and feedin compensation is capped at 0.02€/kWh. But at 3k€ net, who cares? Even with the low electricity rates here, this makes sense. Even for a summer house!

For comparison, my 10 kW solar install completed last week cost 24k CAD (15k EUR). That's just panels, inverters and installation. The incremental cost was likely in part due to the ~160% tariffs on solar panels imposed by the Canadian government, but not all.

and now you know why america's GDP is so high

Prices were high even during the Biden administration.

Markups due to subsidies are a part of it.

My hard drives alone pull 200W idle and I don’t have that many. Cooling fans (in servers) pull 150W total most of the time but can be up to 300W. Each 10GbE NIC pulls ~40W. PoE switch gives ~30W to each of my APs, and uses ~80W itself, so there’s another 300W. All of my RAM pulls about 250W (admittedly there’s nearly 2TB of it in the rack, but still). Start adding up CPUs idle/average/max power and the numbers get way bigger.

If all he’s pulling is 1kW I’m jealous.

Yeah, I wondered the same.

He mentioned that he refuses downsizing for ideological reasons, and I totally get that, but there's a certain amount of rightsizing that doesn't hurt in practical operation, and still let's you keep what feels like an awesome, big, complex model train setup in your garage.

Not all rust has to spin, almost no ports have to be 10GE, and a lot can be virtualized. Consumer CPUs have much lower idle than old xeons, and having less DIMMs with the same capacity also seems to pay off.

I'd be surprised if he couldn't cut that energy usage to 10% with a clear separation between hot and cold storage, and realistic expectations of bandwidth requirements.

But hey, I'm not judging. Solar power is great, and I don't mind waste as long as he can afford it and it makes him happy. Nobody drives the car they actually need either, and that is a much bigger problem.

1kW is less than a toaster, fwiw.

I draw 1-1.5kW for my servers in a spare bedroom. It’s not a lot of spindles/cores, just a few dozen.

No way, man - yes, they overpaid for some of their gear, but the labour cost of an installer ends up being most of what you pay.

No, the smart move here is to find out where the installers buy from, and buy from them. I never explicitly stated I was or wasn’t an installer, they just assumed that I was, as I was buying pallets of panels and kilometres of cabling.

The one advantage of going with a professional installer is that it makes it a lot easier to get grants - I had to spin up a company and invoice myself to get my rebate.

DYI if your dad is an electrician. I wonder what the total would be if he tallied his dad’s assistance at market rates - probably not that much less than the initial quotes he got from professionals.

I have the advantage of living totally off grid and not planning on ever selling the place, so I can have whatever screwy setup I fancy.

Well - I say “off grid” but I’ve built a grid - I now have over a km of buried SWA cable linking the three houses on our land, battery banks at each (60kWh of OPzS down at the mill, 15kWh of LiFePO4 at each of the others), and victron inverter-chargers all over the shop. Two arrays of panels each 8kW, one winter optimised, one summer optimised, and planning on adding a third to make more of the morning sun, as we are in a deep and steep valley with awkward topography. Have mucked around with hydro on and off before landing on a plan for an overshot waterwheel using bits of a burned-out ‘88 hilux, which is my current project. Pessimistically it will give us a constant 1.5kW, but theoretically it should end up nearer 3. Either way, that’s a lot of power. Right now I’m stuck running a Honda generator off our biogas in the winter, and it works, but it’s noisy and I have to go yank the cord to start it, usually in the pouring rain.

Using victron and fronius gear all over, frequency shifting to control where the power goes, and home assistant to automate the whole shebang where it’s beyond what the inverters and chargers can do themselves.

As we aren’t grid connected, the permitting process is… “you do what you want”.

It’s all far, far more straightforward than most people think - the hard bit is the physical install, as you’re inevitably lugging awkward panels onto roofs or up cliffs (going for smaller panels can help with this if you’re doing it without any help), or incredibly heavy batteries to wherever they need to be. The lithium arrays weigh about 150kg each, the lead array the better part of 2000kg.

People assume it must have cost hundreds of thousands of euros, but no - all in it has been about €30k, and our ongoing costs are zero.