[Justa]

I use an APC 1500VA/900W Back-UPS Pro filled with 10Ah LiFePO4 Lithium Batteries. Probably a bigger factor is that I live a ways from the power plant and far back on the transformer connections. Any lightening strike or transformer over voltage has so far been taken care of by the UPS.

Just in case tho I keep a NIB spare computer power supply in one of my safes (along with family photo SD cards) -for additional gamma ray shielding -a completely under appreciated vulnerability for civilian infrastructure imo. I have metal roofs for alpha and beta particle shielding aka Carrington events.

[Tell It Right]

I have two Sol-Ark 12kW indoor solar inverters (working in parallel). I wish I had a dollar for every time my inverters beep and warn that it had to disconnect from the grid for a few seconds over dirty power. But usually not the slightest blip in lights in my home. The inverters act as a first line of defense between my house and the grid. They're hybrid inverters. That means that the electrical panels aren't in the line between the meter and the inverters (like normal grid-tied inverters). The inverters have multiple circuits coming out of them and act like a traffic cop directing all electrical "traffic" between each entity in my system:

1) DC solar power coming from solar panels to inverters,
2) DC circuit from inverters to/from battery array,
3) AC circuit from inverters to electrical panels of home, and
4) AC circuit from meter (grid) to inverters.

It looks like this (minus the backup generator):

My inverters have a jack for hooking up a backup generator and can start/stop a generator automatically. But that jack can't be used for both a generator and what my inverters call "smart load". I use the smart load feature to save me tons of money on charging the EV. It powers a small electrical panel intermittently, only when the home battery stack is charged to 80% (configurable by me). The idea being that if the home batteries are charged that much I'll almost certainly power the home through the night without pulling from the grid. Thus of the two EV chargers we have, we usually use the one that's powered intermittently (most of our miles driven are charged by free power). If we come home in the EV with less than 100 or so miles of range, we charge it with the constantly powered charger (always on, but not always free). Topping off the EV at 80% charged (recommended top) gives a range of about 230 miles. If we come home with more than 100 miles range we plug in the intermittent charger (may or may not get charge, and if we do it may not top the EV at 80%). So a good sunny day of a free EV charge is enough for a few days in a row of free driving even if the next couple of days are rainy (no free power to charge) before we decide to quit hoping for a sunny day and charge with constant power.

There's a bus array of 18 lithium batteries, each 5Ah LifePo4's. Total of 90kWh storage, and can handle total of 90kW input/output. (In other words, if my 20kW of solar was to all be going into charging the batteries on a sunny day in which my home load was practically zero, the batteries can easily handle 20kW coming in. The same for if I'm drawing 18kW from the batteries to power the home at night.) The battery array doesn't offer the UPS logic directly --- it's understood that the inverters have the UPS logic for when to pull from the batteries. Usually I have the inverters set to not act like UPS but more in the logic of saving my money. In other words, the inverters will drain the batteries at night or on rainy times down to 30% left on SOC (strength of charge) before pulling from the grid. However, if the weatherman predicts a storm I might change the inverter settings to more of an UPS mode (high priority of keeping the batteries charged and only when they're fully charged is incoming solar power used to reduce grid pull).

I didn't think about my metal roof being used to shield from emp. How do you provide connectivity through the walls to the ground? And is it needed anyway? I've seen tests in which even small/sensitive electronics like laptops survive Emp through the air (just need a reboot). It's Emp transmitted on the electrical line going into the home that tends to cause damage, if I understand it correctly.