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. 🙂
Deliverer schrieb:
You still have to divide that by four, then you get the power consumption.
Just sayin'...How should I understand this? Are the energy or heat demand calculations generally set much too high, or am I calculating incorrectly? I used the Qp value.
Thank you. Is it possible to roughly estimate the heating electricity consumption of a new building using the Qp value from the heat demand calculation (building permit / planning permission application for KfW), or does this calculation not make sense?
Usable floor area 270 sqm (2900 sq ft) * Qp 35 kWh (per m² per year) = 9450 kWh per year / 4 = approx. 2500 kWh per year.
That seems far too low to me.
Usable floor area 270 sqm (2900 sq ft) * Qp 35 kWh (per m² per year) = 9450 kWh per year / 4 = approx. 2500 kWh per year.
That seems far too low to me.
D
Deliverer24 Jan 2022 08:47There are many factors involved now (mainly the plumbing), but roughly speaking, that fits.
R
RotorMotor24 Jan 2022 09:15Maxwell8 schrieb:
Thanks. Is it possible to roughly estimate the heating electricity consumption of a new build using the Qp value from the heat demand calculation (KfW application), or does that calculation not make sense?
Usable floor area 270 sqm (2900 sq ft) * Qp 35 kWh (per m² per year) = 9450 kWh pa / 4 = approx. 2500 kWh pa.
That seems way too low to me.Although this doesn’t really relate to the topic of photovoltaics and air-to-water heat pumps, the 2500 kWh figure isn’t that unlikely. I find the Qp value hard to interpret, because some additional factors are often included to calculate the energy.
For electricity, something around 2.
So it’s better to look at the heating load rather than the primary energy demand.
As much as I regret it, in my opinion the seasonal performance factor (SPF) does not matter here. What counts is the final energy demand (which is also shown in the calculations). This is the actual electricity measured by meters and systems. The QP value is the final energy multiplied by a politically motivated factor. As far as I know, this factor for heat pumps is currently 1.6. That means @Maxwell8 the actual electricity consumption would be:
Usable floor area 270 m² (2900 ft²) * QP 35 kWh (per m² per year) = 9,450 kWh/year. Divided by 1.6 = 5,906 kWh/year (or about 22 kWh/year per m² usable floor area)
This value includes heating, hot water, ventilation, and auxiliary energy (pumps etc.). @Maxwell8, do you find the final energy in your documents, and does it match my tentative claim?
Usable floor area 270 m² (2900 ft²) * QP 35 kWh (per m² per year) = 9,450 kWh/year. Divided by 1.6 = 5,906 kWh/year (or about 22 kWh/year per m² usable floor area)
This value includes heating, hot water, ventilation, and auxiliary energy (pumps etc.). @Maxwell8, do you find the final energy in your documents, and does it match my tentative claim?
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