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!
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!
N
nordanney9 Feb 2026 09:06Pianist schrieb:
That’s a good start. Does anyone else have thoughts about the overall project? Or is my father the only one who wants something like this? I think you need to visit a specialized prepper forum. Most “normal” people don’t worry so much about a power outage and don’t want to spend extra money on it unnecessarily.
So yes, your father is definitely a bit of a special case.
There is a professor somewhere in West Germany who made his house completely self-sufficient back in the early 2000s. He used a (surprisingly small) photovoltaic system, storage, and a combined heat and power unit for the winter. He also has a manual switch that allows him to connect to the grid if necessary, but I don’t think he actually needs it.
There was a report about this on WDR at some point. Unfortunately, I don’t know the name of the program or the gentleman.
But what it shows is that it is possible—and today, it would most likely be much cheaper than back then. What might complicate things for you a bit is supplying two single-family homes. But that’s probably more of an official issue; technically, it should work with enough money.
I believe that in Germany, investing in a storage system with black start capability is sufficient. The likelihood of having to manage without power for several weeks is quite low. And if you design one part for that, you would have to design everything else accordingly. Consider that during a widespread power outage, infrastructure wouldn’t work either. For example, drinking water (waterworks pumps would stop) wouldn’t be available. So you’d also have to keep drinking water tanks with several cubic meters, regularly replace the water, flush the tanks, and completely renew them every 5–10 years. Well, then it really becomes a prepper thing, as @nordanney already mentioned.
There was a report about this on WDR at some point. Unfortunately, I don’t know the name of the program or the gentleman.
But what it shows is that it is possible—and today, it would most likely be much cheaper than back then. What might complicate things for you a bit is supplying two single-family homes. But that’s probably more of an official issue; technically, it should work with enough money.
I believe that in Germany, investing in a storage system with black start capability is sufficient. The likelihood of having to manage without power for several weeks is quite low. And if you design one part for that, you would have to design everything else accordingly. Consider that during a widespread power outage, infrastructure wouldn’t work either. For example, drinking water (waterworks pumps would stop) wouldn’t be available. So you’d also have to keep drinking water tanks with several cubic meters, regularly replace the water, flush the tanks, and completely renew them every 5–10 years. Well, then it really becomes a prepper thing, as @nordanney already mentioned.
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