ᐅ Backup power system for two single-family homes

Created on: 6 Feb 2026 16:41
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Pianist
Good day!

Due to the power outage in southern Berlin, my father considers it necessary to examine to what extent it is possible to prepare for such an event, and he has asked me to gather relevant information. Before I speak with an electrical contractor, I would like to understand the technical and legal conditions under which this could be done.

It is important to distinguish between a "temporary solution" (where only the heating system is powered) and a proper installation (where the entire house is supplied). Additionally, one should clarify whether major appliances such as the stove and oven are included or not.

In theory, a diesel generator (with HVO 100 fuel in the tank to prevent degradation) could suffice if a supply connection point has been created at both houses, for example under a stair landing or similar. The supply lines to the heating systems would then be disconnected (each originating from the emergency switch) and connected to the supply point, while the generator runs outside.

A proper installation as part of the overall system would, however, need to ensure that when the generator is in use, the connection to the public grid is simultaneously disconnected. This is necessary firstly to prevent backfeeding, and secondly because the grid power would eventually be restored.

I don’t believe that a well-insulated house would cool down enough over a week for the heating pipes to freeze, but he wants me to clarify this.

Thank you, Matthias!
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nordanney
11 Feb 2026 07:57
Pianist schrieb:
why there is no solution that satisfies him...

Yes, there is. Just stay a few days in a good hotel and let yourself be pampered. Over the next 20 years, this will probably be much cheaper than spending a lot of money now on technical things you only need theoretically but still have to maintain regularly.
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Pianist
11 Feb 2026 08:25
Exactly. But he is worried that after a few days the heating pipes might freeze and burst. We recently discussed this here and concluded that it won’t happen. My impression is that people beyond a certain age tend to focus only on the problems and live in fear, even if it is completely irrational. By the way, this also explains voting behavior (fortunately not with my parents)...
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GeraldG
11 Feb 2026 10:42
At least one family where the parents do not vote Green.
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Pianist
11 Feb 2026 10:52
I did not claim that. In any case, they do not choose the one party that primarily spreads fear. Are political topics actually welcome here? Many forum moderators don’t allow them because they tend to escalate quickly...