Using a hot water tank as a battery is an incredibly simple idea. I wonder how much electric hot water heaters on a timer could flatten California's duck curve.
They have been controlling hot water tanks in New Zealand for decades… probably since the 70s. They use what they call a ripple signal by adding 400 hz on top of the 60 and then relays on your hot water tank detect the 400hz and switch it off
We also control (or used to control) our street lights in AoNZ using ripple control (it was implemented with a tuned reed relay in some towns). Back in the 70s friends built a ripple transmitter and sent morse across Ōtepoti by turning on/off their suburb's street lights (at 2am)
There’s a company doing that in Hawaii, I think it’s called “shift energy”. I interviewed with them, it seemed like a great operation, but a bit hobbled by being a startup in Hawaii. I respect it though, I’d do the same.
