Solar for hot water/heating or better photovoltaic for electricity?

What is it that people in this forum have against the gas-powered solar water heater? Too simple? Too cheap? My approach is, it works and is quite affordable. Completely without gas would be better, but the law does not allow it. Photovoltaics, on the other hand, are only economically viable here with subsidies. And everyone pays for that, especially the many millions in rental apartments. Which I think is a scandal. Karsten

Too susceptible and uneconomical.

A controlled residential ventilation system will also be installed in our house. We still need to have it calculated. I was mainly interested in the order in which I should ask the building authorities. So... is the Energy Saving Ordinance complied with using gas, a central ventilation system with heat recovery, and 1. Photovoltaics 2. Solar for hot water support and heating. Is that how you would proceed?

If controlled residential ventilation, it may even work without additional [Zusatz]. Only gas. Check it.

No. You use gas with controlled residential ventilation and calculate whether that is sufficient. If it is sufficient, you do nothing further (unless you really want to because you like photovoltaic or solar thermal). If it is not sufficient, you ask whether it is possible to achieve it in another way, for example by further improving the insulation. If none of that helps, you use solar thermal. Photovoltaic, as mentioned, will not help you further because it does not contribute to heating the building when using gas (keyword regenerative share). Photovoltaic only slightly reduces your primary energy demand because the yields are (partly?) offset.

What is it that people in this forum have against the gas hot water solar system? Too simple? Too cheap? My approach is that it works and is quite inexpensive. Completely without would be better, but the legislator does not allow that. Photovoltaics, on the other hand, are only economically viable here with subsidies. And everyone pays for that, especially the many millions in rental apartments. Which I find outrageous. Karsten

It probably also has hard economic reasons. I (built 2011, Energy Saving Ordinance, 155m2, air-water heat pump without solar) need only 10% of my energy for hot water. In this constellation, photovoltaics would of course make sense, but just the ratio of hot water to heating (regarding energy demand) is probably not that different with gas (more likely even less for hot water). At this low level, practically nothing more can be saved...


der Steph