> and with batteries you end up fully self sufficient when the grid goes down.
My understanding is that the majority of installs are not capable (allowed?) to run when the grid is down. I do know that at the very least you'd need a transfer switch to ensure you're not backfeeding the grid when it's not expecting it, like with a generator.
Now that I think about it, I wonder if a generator could provide the reference signal for the inverters to synchronize against. You'd still be burning fuel at whatever the generator's idle consumption is, but that'll be less than actually using it for power.
Nah. It’s a standard feature of most battery systems to run when the grid is down. Solar without battery doesn’t, (and the solar itself cuts out) but if you have battery systems involved for storage, you’re already capable of them interoperating with the grid, or without it.
As for getting reference from a generator, no need. You can get all that from the batteries and they’re increasingly planned to be used for grid scale black start.
> My understanding is that the majority of installs are not capable (allowed?) to run when the grid is down.
Capable, IIRC. I seem to remember that you need to have a type of inverter that is quite a bit more expensive (several kilodollars) if you want to be able to run disconnected from the grid.
Most people opt for the cheaper inverter as there's not a lot of difference if you don't also have a battery storage system.
Most offgrid inverters have a generator input to which they will switch when you start the generator. If you replace the generator with the grid (and you have batteries) and the grid goes down they switch seamlessly to the batteries - well, within a fraction of a second, some applainces "blink". I am actually using this system as a sort of UPS for our office
Separate outlets means running cable that you won't use most of the time, and having to remember which outlets go to which circuit.
A transfer switch allows you to isolate and switch between two power supplies so that your house circuits are only ever connected to one of them, and the two supplies are never in the same circuit[1]. They can be had for a few hundred depending on the load[2].
[1] this is a break-before-make switch. There exist make-before-break switches for when you need uninterrupted power supply, but they're not appropriate for this case as you'd be backfeeding into the grid which is dangerous and illegal.
My understanding is that the majority of installs are not capable (allowed?) to run when the grid is down. I do know that at the very least you'd need a transfer switch to ensure you're not backfeeding the grid when it's not expecting it, like with a generator.
Now that I think about it, I wonder if a generator could provide the reference signal for the inverters to synchronize against. You'd still be burning fuel at whatever the generator's idle consumption is, but that'll be less than actually using it for power.