Sunamp.com seems to be just ohmic heating for thermal usage of excess electricity.
I thought sunamp is some kind of room temperature phase change material that does not require heavy insulation.
It does use a PCM, and that is described as a salt so maybe it's where the confusion comes from.
It also has far better insulation than equivalent devices (hot water cylinders). Typically VIPs, although I've read a few reports about the casing being compromised recently and that wouldn't play nicely with the panel.
- https://reneweconomy.com.au/mit-team-gains-ground-on-molten-...
- https://1414degrees.com.au/ (which looks like a competitor for malta)
(Not knowing much about the chemistry, I’m naively conflating the two)
Edit to add: Sunamp has non-zero heat loss, so it must be stored hot rather than room temperature, but it might not be very hot.
They make a molten salt heat battery for homes and businesses. You store excess heat or electricity in the battery, and use it for central heating and hot water. Since you’re not trying to convert it back to electricity it’s very efficient. It basically replaces a large expensive water cylinder with a smallish box.
PS: I have no connection with or investment in Sunamp, I just think it’s a terrific idea. I am a potential customer, though!