Was going to mention Sunamp. 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 insulatio

Was going to mention Sunamp. 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.