ᐅ Solar for hot water and heating, or is photovoltaic better for electricity?

What is it with this forum’s negative attitude toward solar water heating systems combined with gas? Too simple? Too cheap? My approach is that it works and is quite affordable. Having no gas at all would be better, but it is not allowed by the regulators.

On the other hand, photovoltaic systems are only economically viable in our regions because of subsidies. And everyone pays for that, especially the many millions living in rental apartments. I find that really unfair. Karsten

Too vulnerable and uneconomical.

A mechanical ventilation system with heat recovery will also be installed in our house. We still need to have the calculations done. I was mainly interested in the order in which I should ask the building authority.

So... is compliance with the energy-saving regulations achieved using gas, a central ventilation system with heat recovery, and
1. Photovoltaic panels
2. Solar thermal for hot water support and heating

Is this how you would proceed?

If using a mechanical ventilation system with heat recovery, it might even be possible without additional heating. Just gas. Check it.

No. You choose gas with controlled residential ventilation and then calculate whether that is sufficient. If it is sufficient, you don’t need to do anything further (unless you want to for reasons like installing photovoltaic panels or solar thermal systems).

If it’s not sufficient, ask whether there are other options to improve, for example by increasing the insulation.

If none of that helps, you use solar thermal systems. Photovoltaics, as mentioned, won’t really help because with gas heating they do not contribute to heating the building (keyword: renewable share). Photovoltaics only slightly reduce the primary energy demand because the energy produced is partly credited in the calculations.

Nordlys schrieb:
Why is there so much opposition to gas-assisted solar water heating systems in this forum? Too simple? Too cheap? My approach is that it works and is quite affordable. Of course, completely without gas would be better, but the law doesn’t allow that. On the other hand, photovoltaic systems are only economically viable in our region with subsidies. And everyone pays for that, especially the millions of people living in rental apartments, which I think is unfair. Karsten

There are probably strong economic reasons as well. I built in 2011 under the energy saving regulation, with 155m² (1674 sq ft) and an air-to-water heat pump without solar. I only need 10% of my energy for hot water. In this setup, photovoltaic would obviously make sense, but the ratio of energy needed for hot water versus heating with gas is probably not that different (possibly even less for hot water). At such a low level, practically no more savings can be made...


derSteph