ᐅ New Construction with a Separate Apartment: Solar Power – Electricity – Heating
Created on: 15 Jul 2024 22:21
T
Tobi_SLHello,
I know some of my questions have been touched on in other threads but were never answered in detail. So here is my specific situation:
My wife and I want to build a single-family house on a slab foundation with an additional granny flat on the ground floor for my mother-in-law. We already have a plot of land (750 sqm (8,073 sq ft)).
Of course, we want a photovoltaic system on the gable roof with as many kWp on the south side as possible. I have read here that the system can only be connected to one electrical circuit. The granny flat would therefore be permanently connected to the external grid. That much is clear.
My main question concerns the heating system (air-to-water heat pump): Can the heat pump and the rest of the heating be powered entirely from the electricity of the main apartment (with photovoltaic)? Or does that also have to be split somehow?
We would, of course, like to use as much photovoltaic electricity as possible. If we were to rent the granny flat externally at some point, we would simply arrange a flat-rate rent including heating costs. Would that comply with legal requirements? Or does the electricity for heating costs also have to be accounted for separately?
One more thing in conclusion: I have noticed that prefab house providers often charge significant premiums for photovoltaic systems compared to the open market, and you often cannot choose components freely. On the other hand, it is said that a system planned directly by the builder along with the house is better integrated into the overall project. Would you still recommend contracting the photovoltaic system externally? What should be considered during house planning in this case to ensure the installation and integration go as smoothly as possible?
Thanks in advance!
I know some of my questions have been touched on in other threads but were never answered in detail. So here is my specific situation:
My wife and I want to build a single-family house on a slab foundation with an additional granny flat on the ground floor for my mother-in-law. We already have a plot of land (750 sqm (8,073 sq ft)).
Of course, we want a photovoltaic system on the gable roof with as many kWp on the south side as possible. I have read here that the system can only be connected to one electrical circuit. The granny flat would therefore be permanently connected to the external grid. That much is clear.
My main question concerns the heating system (air-to-water heat pump): Can the heat pump and the rest of the heating be powered entirely from the electricity of the main apartment (with photovoltaic)? Or does that also have to be split somehow?
We would, of course, like to use as much photovoltaic electricity as possible. If we were to rent the granny flat externally at some point, we would simply arrange a flat-rate rent including heating costs. Would that comply with legal requirements? Or does the electricity for heating costs also have to be accounted for separately?
One more thing in conclusion: I have noticed that prefab house providers often charge significant premiums for photovoltaic systems compared to the open market, and you often cannot choose components freely. On the other hand, it is said that a system planned directly by the builder along with the house is better integrated into the overall project. Would you still recommend contracting the photovoltaic system externally? What should be considered during house planning in this case to ensure the installation and integration go as smoothly as possible?
Thanks in advance!
N
nordanney15 Jul 2024 22:35Tobi_SL schrieb:
I have already read here that the system may only be connected to one electrical circuit. So the secondary unit would be permanently connected to the external grid. Fair enough. No, you can also implement the topic of "tenant electricity." Whether you enjoy that is another question.
Tobi_SL schrieb:
My main question concerns the heating (air-to-water): Can the heat pump and the rest of the heating system be entirely powered by the electricity from the main dwelling (with photovoltaic)? Or does that have to be divided somehow? Where is the heat pump connected? If it’s on the same circuit as the photovoltaic system, it’s almost unavoidable.
Tobi_SL schrieb:
If we ever rent out the secondary unit externally, we would simply agree on a flat-rate rent including heating. Would that comply with the law? No. A flat-rate rent including heating is not legally compliant. You can still do it if the tenant doesn’t complain. grin
Tobi_SL schrieb:
One last thing: I have noticed that prefab house providers always charge a hefty premium for photovoltaic systems compared to the open market, and you often can’t choose the components as you like. On the other hand, it’s said that a system planned directly with the house by the builder is better integrated into the project. Nonsense. The house sellers just want to make big profits. They usually just slap the same system on all 32 house types and configurations without further planning.
Tobi_SL schrieb:
Would you still subcontract the photovoltaic system? What should be considered during house planning to ensure smooth installation and integration? Not “still,” but definitely. What to consider? Either incorporate it directly into the building planning (coordinating cable routes, electrical setup) or simply prepare empty conduits.
Wow... that was quick. Thank you very much for the response.
I’m just wondering how I should calculate the heating costs for the rented granny flat proportionally when the energy for the heat pump/heating comes from my electrical circuit, which is partly supplied by the photovoltaic system and the external grid? And even if you manage to calculate a reasonable amount for the total heating costs: how can you determine the share of the underfloor heating for the granny flat in the overall total? Is it possible to separately read the different water circuits and their respective energy consumption?
I’m just wondering how I should calculate the heating costs for the rented granny flat proportionally when the energy for the heat pump/heating comes from my electrical circuit, which is partly supplied by the photovoltaic system and the external grid? And even if you manage to calculate a reasonable amount for the total heating costs: how can you determine the share of the underfloor heating for the granny flat in the overall total? Is it possible to separately read the different water circuits and their respective energy consumption?
Malle Zwabber16 Jul 2024 04:21Simply install a heat meter for each apartment. This way, the exact consumption for each unit can be determined, similar to an electricity meter.
To use photovoltaic electricity also for heating, there is a special measurement system (MK8). This means your meter cabinet would need space for at least 3 meters. However, I am unable to advise on the tax implications of this setup.
To use photovoltaic electricity also for heating, there is a special measurement system (MK8). This means your meter cabinet would need space for at least 3 meters. However, I am unable to advise on the tax implications of this setup.
H
Haus Luni16 Jul 2024 07:27Hello,
Perhaps a tax advisor can help here. I think the main question is how to properly report this in a tax return.
We currently have a rental agreement for a secondary apartment where we do not know the exact water and heating consumption. The rent is below average, and we are only interested in the monthly rent amount. We have even agreed with the tenant that they can set the utility costs higher separately, which gives them tax advantages. For this, we neither receive additional payments nor refunds. There is a separate meter for electricity.
However, I don’t know how they handle this in their annual tax return.
Perhaps a tax advisor can help here. I think the main question is how to properly report this in a tax return.
We currently have a rental agreement for a secondary apartment where we do not know the exact water and heating consumption. The rent is below average, and we are only interested in the monthly rent amount. We have even agreed with the tenant that they can set the utility costs higher separately, which gives them tax advantages. For this, we neither receive additional payments nor refunds. There is a separate meter for electricity.
However, I don’t know how they handle this in their annual tax return.
N
nordanney16 Jul 2024 07:55Tobi_SL schrieb:
I’m just wondering how to fairly calculate the heating costs for the rented granny flat when the energy for the heat pump/heating comes from my electrical circuit, which is partly powered by the photovoltaic system and partly by the external grid? This is indeed an interesting challenge. A topic for your tax advisor, since this also involves tenant electricity.
Tobi_SL schrieb:
How should the share of the underfloor heating for the granny flat be determined from the total amount? Separate circuits, heat meters—just like in any standard multi-family building.
Or you keep it simple. Just install a small heat pump for each apartment. That’s how I did it in my place.
nordanney schrieb:
No. A flat rent including heating is not legally compliant. You can still do it if the tenant doesn’t mind. grin I replied too quickly yesterday. It’s a granny flat, not a multi-family house. You’re allowed to include utilities in the rent in that case.
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