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
WilderSueden14 Jan 2022 13:11face26 schrieb:
Hmm, I would argue that it’s smarter to run a 10 kWp system with 30% self-consumption than a 4.8 kWp system with 50%.Well, 3 kW self-load versus 2.4 kW is obviously better at first glance. The question is whether the additional 25% self-consumption justifies the higher price of a system twice as large. With a feed-in tariff of around 6.x cents that I will receive for my system, it’s questionable whether that isn’t below the production costs. You can expect around 1000 kWh per kWp, which over 20 years amounts to about €1200–1300 (without considering opportunity costs and depreciation). That might sound decent at first, but it’s roughly the amount it costs to install it on the roof. Opportunity costs and loss of value over time are not included.But let’s see, maybe the new government will still make changes in time.
WilderSueden schrieb:
With a feed-in tariff of around 6.x cents that I will receive for my system, it is questionable whether this is below the production costs. You can expect about 1000 kWh per kWp, which amounts to 1200-1300€ over 20 years.With a smaller system, you face the same issue, even more so, since smaller systems usually have a higher cost per kW than larger ones. In absolute terms, however, larger systems allow you to use more electricity yourself, especially in winter or during off-peak times when you still get a bit more output. You can check a well-known forum on the topic to see how this is generally viewed.
W
WilderSueden14 Jan 2022 13:33face26 schrieb:
With a smaller system, you still have the same issue. Even more so, since smaller systems usually have a higher price per kW than larger ones. It depends on how you calculate it. For us, the walls were already quite good, and I could also make the case that the minimal system with minimal storage costs basically nothing due to the jump from KfW55 to 40+, and every additional module then needs to justify itself financially. Not just breaking even, but compared to a profitable investment, say 5% per year.
But I still need to have the general contractor arrange for the solar expert to discuss extension options. I keep thinking about installing something on the carport to get a second orientation (SSE on the house, WSW on the carport). But that would, of course, be a second installation.
One problem with forums is that each has its own community with common sense and tends to overlook some things. In a house building forum, investing money is primarily about real estate; in a solar forum, the focus is on how much you can save with solar systems; and in a stock market forum, stocks are the ultimate. Weighing all that against each other is not so easy.
WilderSueden schrieb:
Self-consumption is what determines profitability nowadays. It doesn’t help to produce tens of thousands of kWh if you feed them into the grid at only 7-8 cents while paying much more for your own electricity. However, surplus is the key. Feeding that into the grid at 8-9 cents is not a bad option either. Of course, it doesn’t sound like much. And with a 5 kWp (kilowatt-peak) system, it’s not significant, which is why I plan to fully cover the roof and benefit from it as long as possible. That’s at least my plan.
But now, our hipped roof shape is complicating things for us.
Roughly speaking, for our region and including all costs, with 25% self-consumption, the system will pay off after 10-12 years.
Stiftung Warentest offers a very good calculation tool for this. Or you can find one in the photovoltaic forum.
Of course, I might be wrong in some assumptions.
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