ᐅ Photovoltaic System and Air-to-Water Heat Pump – Profitability for a Single-Family Home Built to KfW 55 Energy Efficiency Standard
Created on: 11 Jan 2022 23:19
M
Maxwell8
Hello,
we are building a fairly large KFW55EE house with external dimensions of approximately 10x14m (33x46 feet) and a roof pitch of 15° (roof surfaces facing north and south).
We have a lot of window area (100m2 (1,076 sq ft)) and expect an energy consumption of about 7-9k kWh per year due to the size.
Heating is provided by underfloor heating with the Tecalor THZ 504 air-to-water heat pump.
Feed-in tariffs are no longer significant, but the electricity price is currently 45 cents/kWh.
We would have to finance the photovoltaic system ourselves because there is no sufficient budget left.
> From a profitability perspective, does a photovoltaic system make sense in our situation?
> What size and costs should we expect?
> Should it be installed directly or should we first prepare with conduits?
> We also have an attached 6x6m (20x20 feet) flat-roof garage on the east side. Would adding photovoltaic panels there be beneficial?
I will, of course, speak with companies but would like to gather some opinions beforehand.
Thank you in advance. 🙂
we are building a fairly large KFW55EE house with external dimensions of approximately 10x14m (33x46 feet) and a roof pitch of 15° (roof surfaces facing north and south).
We have a lot of window area (100m2 (1,076 sq ft)) and expect an energy consumption of about 7-9k kWh per year due to the size.
Heating is provided by underfloor heating with the Tecalor THZ 504 air-to-water heat pump.
Feed-in tariffs are no longer significant, but the electricity price is currently 45 cents/kWh.
We would have to finance the photovoltaic system ourselves because there is no sufficient budget left.
> From a profitability perspective, does a photovoltaic system make sense in our situation?
> What size and costs should we expect?
> Should it be installed directly or should we first prepare with conduits?
> We also have an attached 6x6m (20x20 feet) flat-roof garage on the east side. Would adding photovoltaic panels there be beneficial?
I will, of course, speak with companies but would like to gather some opinions beforehand.
Thank you in advance. 🙂
W
WilderSueden12 Jan 2022 08:33Maxwell8 schrieb:
There is a large window area (100m2 (1,076 sq ft)) and, due to the size, an expected annual energy consumption of 7-9k kWh.
Heating is provided by underfloor heating with the Tecalor THZ 504 air-to-water heat pump. In winter, you probably won’t get much benefit from the photovoltaic system. In good weather, you will heat with solar gains and will likely end up too warm rather than too cold. In bad weather, the photovoltaic system generates relatively little electricity compared to the heat pump. The low roof pitch further reduces efficiency in winter.
For profitability, it will be more important whether you can also use the electricity in summer. In other words: Are you home during the day?
The same question applies for bidirectional charging. How often does the electric car leave in the morning and only return in the evening?
If he can charge for free at the employer’s location, the vehicle will arrive at home nearly fully charged. The question then is whether this constitutes a taxable benefit that needs to be accounted for in terms of taxation (regardless of whether the employer will tolerate this for a long time).
When will construction start, and by when do you need to decide on the photovoltaic system? There will likely be short-term changes in approvals, bureaucracy, and subsidies for photovoltaic systems—probably not for the worse. Therefore, I would suggest finding a solar installer to plan with, but possibly only give the official order once the new regulations are available. If you have to finance it entirely yourself, that’s not a problem. There are also KfW loans available for this, and usually the loan payments are easily covered by feed-in tariffs or your own electricity savings.
What kind of roof is it exactly? A single-pitched roof, facing south?
What kind of roof is it exactly? A single-pitched roof, facing south?
We have the THZ 504 installed in a KfW55 standard house.
In 2021, we covered about 14% of our energy costs with photovoltaic power (4.55 kWp with a relatively ideal roof pitch and orientation), with the rest coming from the grid.
During the months when the system consumes the most electricity, photovoltaic generation is very low. Good synergy occurs in the transitional seasons of autumn and spring, as well as in summer for hot water and ventilation. However, we also have a software component that converts excess photovoltaic energy into warmer water before it is fed back into the grid.
Nevertheless, I am absolutely in favor of photovoltaics. We have basically financed ours as well. There are few other investments that almost pay for themselves.
In 2021, we covered about 14% of our energy costs with photovoltaic power (4.55 kWp with a relatively ideal roof pitch and orientation), with the rest coming from the grid.
During the months when the system consumes the most electricity, photovoltaic generation is very low. Good synergy occurs in the transitional seasons of autumn and spring, as well as in summer for hot water and ventilation. However, we also have a software component that converts excess photovoltaic energy into warmer water before it is fed back into the grid.
Nevertheless, I am absolutely in favor of photovoltaics. We have basically financed ours as well. There are few other investments that almost pay for themselves.
Hangman schrieb:
When is construction starting, and by when do you need to decide on the photovoltaic system? There will likely be short-term changes in approval processes, bureaucracy, and subsidies for photovoltaic systems—probably not for the worse. Therefore, I would recommend finding a solar installer to help plan this with you, but possibly only give the official order after the new regulations are in place. If you need to finance it completely yourself, that’s not a problem. There are also KfW loans available for this, and usually the repayment is easily covered by feed-in tariffs or savings on your own electricity.
What kind of roof is it? A single-pitch roof facing south?Construction is scheduled to start around May/June 2022, with completion in spring 2023.I thought so too, but the subsidies will probably be added onto the prices by the providers.
A gable roof with a 15° pitch (roof surfaces face north and south).
kati1337 schrieb:
We are using the THZ 504 in a KFW55 house.
In 2021, we covered about 14% of our energy costs with photovoltaics (4.55 kWp with a relatively ideal roof pitch and orientation), the rest came from the grid.
Ouch, since I am currently in the process of buying a photovoltaic system myself, the 14% feels like a slap in the face. Why so low? Why generate hot water instead of feeding the electricity back into the grid, even if the compensation is only 7 or 8 cents?
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