The Rheem heat pump for domestic hot water that I have in my home claims a maximum energy savings of 75%. That implies that at 20% efficiency out of my solar panels, the efficiency of photovoltaic panels + the heat pump is equal to the 80% efficiency of solar hot water. However, this ignores losses from DC to AC and the lines.
The photovoltaic panels have the added bonus that the energy can be used for other purposes (e.g. transport, HVAC, computers, cooking, laundry, A/V equipment) should my hot water needs be low compared to what the system is designed to produce. However, from a pure efficiency standpoint, it is unclear to me which approach is better. They seem to be a rough tie, with losses for both approaches making the real world worse than ideal conditions. I am not sure if one is better than the other in the actual real world and if anyone who knows the answer is kind enough to share it, I would find the answer enlightening.
I mean, from a distribution standpoint, electricity is way easier to distribute than heat (pressurized steam? Hot water?) and has less loss over longer distances.
The photovoltaic panels have the added bonus that the energy can be used for other purposes (e.g. transport, HVAC, computers, cooking, laundry, A/V equipment) should my hot water needs be low compared to what the system is designed to produce. However, from a pure efficiency standpoint, it is unclear to me which approach is better. They seem to be a rough tie, with losses for both approaches making the real world worse than ideal conditions. I am not sure if one is better than the other in the actual real world and if anyone who knows the answer is kind enough to share it, I would find the answer enlightening.