Great discussion! I had not thought about the implications for low cost PV competing with solar hot water collectors.
In a home renovation I am planning, am strongly considering the use of a geothermal heat pump for both domestic hot water and for radiant heat. Also incorporating about 10 kW of PV with grid tie. The high COP of the water heater makes sense.
I had not fully recognized the implications of the long term storage of watts "on the grid" but it just makes sense now that I think of it.
Steve
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consulting on geothermal heating/cooling & rational energy use since 1990
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