I designed the system myself, and then I paid a licensed electrical contractor I trusted to check my math and pull the permits, because there's being competent and there's being an idiot about liability, and I've seen what happens to people who confuse the two.
Here is what's on my house, because people always ask, and because it's going to matter.
Forty solar panels, four hundred and ten watts each, sixteen point four kilowatts of DC capacity, on the south and west faces of the roof. Two twelve-kilowatt hybrid inverters, stacked in parallel and configured for 120/240 split-phase, which is the same kind of power any American house gets from the street. Twelve lithium iron phosphate battery modules in a steel rack in the utility room, five point one two kilowatt-hours each, which comes to about sixty-one kilowatt-hours of storage. The residential code caps you at eighty kilowatt-hours of battery in a garage or utility room, and I wanted to stay well under that, partly for the fire marshal and partly because I'm the one who sleeps on the other side of that wall. Lithium iron phosphate is the calm, sensible chemistry. It doesn't like to burn. That's why I picked it.
Behind the garage, screened by a cedar fence that the HOA architectural committee approved after three rounds of revisions, there's a fourteen-kilowatt propane standby generator and a two-hundred-and-fifty-gallon tank. The inverters start the generator automatically if the batteries drop below twenty percent and the sun isn't going to bail them out. In the four years I've lived there, it has run a grand total of a hundred and six hours, almost all of them during stretches of gray winter weather, plus a monthly twenty-minute exercise run that it does on its own on the first Tuesday at two in the afternoon. I picked two in the afternoon on purpose. Nobody's napping.
Everything inside the house is efficient, because off-grid is a game of not needing things. Two ductless mini-split heat pumps. A heat pump water heater. An induction range. LED everything. In spring and fall I use about twenty to twenty-five kilowatt-hours a day. In August, with the mini-splits fighting the heat, it can climb to forty-five. The panels make more than that on a clear day, and most days in Central Texas are clear days.
And then there's the part that makes it truly off-grid, as opposed to just "solar."
Here's the distinction, and I'll say it now because I would end up saying it a dozen times before this was all over. Most houses with solar are grid-tied. They still have a meter. They push their extra power back into the utility lines in the afternoon and pull power back out at night, and if over a year they make as much as they use, people call that net-zero. It's a fine arrangement. But a grid-tied house is still married to the grid. When the grid goes down, the inverters on a grid-tied house are required by code to shut themselves off within a couple of seconds, so they don't send power back up a line that some lineworker like me thinks is dead. That's called anti-islanding, and I've personally been grateful for it more times than I can count. It means, though, that a regular solar house without batteries goes dark in a blackout same as everybody else.
My house isn't married to anything. In April of 2022, I sent Blanco Ridge Electric a written request to permanently retire my service. A crew came out. They pulled the meter, sealed a blank cover plate over the socket, and then opened up the green pad-mount transformer that sits between my lot and the Arreolas' lot across the street and disconnected the conductors that ran underground to my house, and capped them, and left the service line abandoned in the ground. Then they mailed me a letter on co-op letterhead confirming that my account was closed and my service was permanently disconnected, with the transformer number and the meter number and the date and the name of the foreman.
I knew the foreman. I'd trained him. His name is Tomás Reyna, and when he was done he stood in my side yard with his hard hat under his arm and looked at the blank plate and shook his head.
"You know you're crazy," he said.
"I know."
"Your dad would've liked it, though."