Building my own solar power system

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.

I feel like they overpaid maybe because they got direct to consumer rates for the gear. If you would have went through a full on solar installer that solar system would have come out to less than $15k, throw in having to get the subpanel and a reroof you would maybe be looking at $30k all in. (Not including the batteries, but by the time he got to the batteries I feel like his budget was way overboard even going the non-microinverter route).

Make sure you are buying and not leasing from the company, have that all rolled into a single loan and then you claim the tax credits to help pay for the reroof.

To add to this, they take care of getting the certified roofers, the city permits for both the roof and solar and handle the PTO for you, which from what you called out is even more costs.

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.

What should the grid operators do with all that energy that comes in at noon on a beautiful sunny day?

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.