Photovoltaics for hot water

  • Erstellt am 2015-07-02 12:49:32

chrischn

2015-07-02 12:49:32
  • #1
Hello,
we want to build a single-family house with about 200 sqm of living space.
The heating should be a gas condensing boiler.
In the living-dining room, a hydronic stove
and photovoltaic on the roof.

Our energy consultant has now said that if we want KfW 70, we have to install solar thermal on the roof instead of photovoltaic. But I don't really want that.

Now to my question: Does anyone know if hot water with photovoltaic provides
the same as solar thermal?
On the one hand for the KfW application
and on the other hand from an energy perspective? Economic efficiency?

Thanks for your experience and contributions.
Regards
 

Legurit

2015-07-02 12:56:52
  • #2
What a confusing concept. How is the oven accounted for or not at all? Please post the Energieeinsparverordnung documents.
 

chrischn

2015-07-02 13:01:03
  • #3
What is so confusing about it?

Only the percentages are known:
Natural gas: 88%
Wood stove: 3%
Other (electricity): 9%
 

nordanney

2015-07-02 13:02:20
  • #4
Photovoltaics practically do not help (this is what our energy consultant calculated about two years ago) - but it is good for the green conscience if you produce your own electricity.
 

chrischn

2015-07-02 13:04:53
  • #5
But if I can use the electricity for hot water, it is much more profitable. The problem with photovoltaic is only the storage. Then it would also increase.
 

f-pNo

2015-07-02 13:22:03
  • #6
Regarding your question, I can't contribute much. As far as I know, photovoltaics were almost completely disregarded in the calculations here as well.

In general – if you read the forum here – you often find the opinion that solar thermal does not pay off for ages. Whether that's true – I don't know. My father/my sister, who built around 2000, are quite satisfied with the savings on gas.

Contrary to the opinion represented here, an article appeared on t-online last week that praised solar thermal. The gist: Subsidies for photovoltaics have been drastically cut – so it hardly pays off anymore. But with solar thermal, you can get hot water almost for free in spring/summer/autumn. In addition, there is supposedly a subsidy for solar thermal since this year.
Fittingly, the author immediately had the top tip: It's best to put both on the roof. Photovoltaics and ST.

Finally:
There are also providers that offer a combined module variant. The system generates photovoltaic electricity and the heat generated at the modules is used for hot water preparation. When I dealt with this intensively (1.5 – 2 years ago), the whole thing did not pay off. But it may be that prices have changed since then.
 

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