Hello,
we are planning to build a detached house with about 200 sqm (2,150 sq ft) of living space.
The heating system will be a gas condensing boiler.
In the living and dining area, there will be a water-bearing stove.
And photovoltaic panels on the roof.
Our energy consultant said that if we want KfW 70 (a German energy efficiency standard), we need to install solar thermal panels on the roof instead of photovoltaic panels. But I would actually prefer not to do that.
Now to my question: Does solar thermal for hot water provide the same benefits as photovoltaic?
On the one hand for the KfW application,
and on the other hand from an energy perspective? And economically?
Thanks for your experience and input.
Best regards
we are planning to build a detached house with about 200 sqm (2,150 sq ft) of living space.
The heating system will be a gas condensing boiler.
In the living and dining area, there will be a water-bearing stove.
And photovoltaic panels on the roof.
Our energy consultant said that if we want KfW 70 (a German energy efficiency standard), we need to install solar thermal panels on the roof instead of photovoltaic panels. But I would actually prefer not to do that.
Now to my question: Does solar thermal for hot water provide the same benefits as photovoltaic?
On the one hand for the KfW application,
and on the other hand from an energy perspective? And economically?
Thanks for your experience and input.
Best regards
oleda222 schrieb:
Why are you worried so much about whether photovoltaic or solar thermal systems pay off when you’re already spending several thousand euros extra to install a wood stove with water heating in addition to the gas condensing boiler?
That’s not really about efficiency and cost-effectiveness, is it?
You can achieve KfW 70 standard even without solar thermal, but if you can’t reach it despite the wood stove mentioned above, in my opinion you should reconsider the whole concept (insulation?).
If you don’t want insulation suitable for KfW 70, I would rather recommend avoiding the KfW program altogether, so you don’t end up with a lot of “patchwork.”Okay, this post is a bit old. But my question is:
For the building envelope, we are achieving the KfW 55 standard, and due to window ventilation, we lose so much heat that we can’t even reach KfW 70. Now I noticed that in the energy performance calculation according to the Energy Saving Ordinance, at the end under final energy by energy sources, the water-heating wood stove is only listed with 6.5 kWh for heating. Can someone explain why it shows 0.0 for hot water?
T
toxicmolotof16 Jul 2015 13:05Which water does the wood stove heat? Heating and domestic hot water are separate circuits and operate independently.
I could imagine that the stove only heats the heating water buffer tank.
I could imagine that the stove only heats the heating water buffer tank.
We currently use on-demand water heaters and also have a photovoltaic system. Our pellet boiler is intended only for heating, not for hot water. Hot water will continue to be generated using electricity, but one of the on-demand water heaters will be replaced with a domestic hot water heat pump (80 liters (21 gallons) capacity). This heat pump will be powered by photovoltaic electricity. This is said to save a lot of energy, but it also means hot water is constantly kept ready, which is not necessary with on-demand water heaters. Since our annual electricity consumption is currently 3000 kWh INCLUDING hot water (!!!), I am somewhat skeptical about significant savings. The on-demand water heaters are actually very efficient, as reflected in our electricity use, and we also don’t take baths. Of the 3000 kWh, we only had to buy 1800 kWh last year; the rest was produced by the photovoltaic system. However, it should not be overlooked that the photovoltaic system produces almost no power in winter. In December, production ranges between 0 and 2 kWh per day (total capacity max. 7200 watts), which is not enough to make a big difference.
Our plumber initially offered a gas boiler with a 100l (26.4 gallons) hot water tank. However, we then said that we wanted a hydronic stove, and he said the hot water tank would no longer be needed because we would have a buffer tank instead. I thought both heating and hot water would be supplied from there. By the way, he was also surprised that the stove showed 0.0 for hot water.
So, our plumber initially offered a gas boiler with a 100l (26 gallon) hot water tank. Then we said that we would install a water-heated stove, and he said that the hot water tank would be omitted because we would have a buffer tank instead. I thought that both heating and hot water would be supplied from that. By the way, he was also surprised that the hot water capacity was listed as 0.0 for the stove.
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