I wonder how many people have a climate where this would work?
I will say at least 90% of the world if not more has climate where this will not just work but also be more cost effective than any other source.
My location is relatively sunny (sort of average) and about as cold as it gets.
Moving my house and system to many location around the world will still work as it is with some exception's in northern Europe where a slightly larger PV array will be needed but since competing energy sources like natural gas are more expensive there it will still make PV the most cost effective.
For a new house build is even more so as connecting a new house to utilities like electricity and natural gas may cost as much or more than the entire solar system at least for a small house like mine.
Old existing house have the problem that they are improperly insulated meaning they will need a large ground mount array and they may not have the space for such a large array and they may also have large trees or building and so no good access to sun.
Finding things to do with the excess energy may even generate so profit making heating and electricity free or even profitable. For now I have at least 50% of the energy unused in an average year, with as much as 90% unused energy in summer.
That's not necessarily how'd you use it. Ideally you'd use it to heat the water storage tank and then just use any surplus electrical power to do the same. Though I'll admit, unless you need the AC in the summer it doesn't really make sense.
Not sure I understand what you mean.
As one unit uses 2.5kW and outputs say 5kW at a COP of 2 and the PV array provide 5kW then in order to take advantage of all available energy when is available you will need two of this units so that in a sunny afternoon you charge the thermal mass storage with a 10kW rate that is the same sate that I have now. Not using the solar energy when is available means lost energy.
The current setup with direct PV heating and a 10KW PV array plus 158kWh thermal storage provide full house heating in worst case scenario. So the only reason to use a heat pump will be if it will reduce cost and so thermal mass storage capacity will need to remain the same and the only way to reduce cost is to reduce the PV array size as mentioned reducing that to half of current size so 5kW PV array instead of 10kW will save about $4000. Then assuming the heat pump can get an average COP of 2 the same amount of heat can be transferred to thermal storage but since that particular heat pump takes about 2.5kW and outputs 5kW (COP of 2) two of them will be needed to achieve 10kW heat output to be equivalent with direct PV heating and larger PV array.
Result was that to add a heat pump even in a very optimistic use case will result in much higher cost not to mention PV panels will last a minimum 30 years where that heat pump may need replacement every 10 to 15 years depending on quality so even more expensive to the absurd likely it will cost 3x as much to include a heat pump and the only advantage will be needing less pace for the PV array.