It's still used in some projects. I remember seeing a deep dive into a net zero lodge (for vacationing) someone built just a few years ago that featured all of

It's still used in some projects. I remember seeing a deep dive into a net zero lodge (for vacationing) someone built just a few years ago that featured all of those: solar water preheating & PV on the roof, as well as heat pump HVAC/water heaters. Perhaps now it would be cheaper to just beef up the PV and active water heating but I'm sure they had their reasons at the time, at least.