Pellet-solar combination - Issue in summer?

  • Erstellt am 2021-04-15 14:41:55

XxTankerxX

2021-04-15 14:41:55
  • #1
Hello everyone,

I am currently in talks with the first heating engineers. The centerpiece will be a pellet heating system (15kW) -> ETA or KWB. Since I have only heard good things about a solar combination so far, I wanted to implement this now as well. I expect (almost) complete savings of pellets in the summer – solar should be sufficient for pure hot water preparation.

After the conversation with the heating engineer, I am now somewhat uncertain. He told me about problems with such a combination, as too much heat is generated especially in the summer (since hardly any water is needed from the buffer tank), and the glycol in the solar panels partially even evaporates because it gets too hot. He, on the other hand, would rather use photovoltaics and implement heating support with an electric heating rod. I heard about this problem for the first time and also cannot find much about it on the internet.

What do you think about this? Maybe one of you has experience with one of the two heating technologies.

Best regards,
XxTankerxX
 

nordanney

2021-04-15 14:49:21
  • #2

I would ALWAYS prefer photovoltaics over solar thermal energy. Exactly for the reason that the sun shines in summer and you don't know what to do with it. You can't shower continuously that often.
How about photovoltaics and a domestic water heat pump or something similar?
 

Mycraft

2021-04-15 15:47:49
  • #3
Solar thermal energy is good if you have it for free (or get it for free). Otherwise, photovoltaic because you can also use the electricity (sun) for other purposes.

But yes, of course, a 5sqm solar thermal system covers the hot water demand of an average household on average from March to October in our latitudes.

The glycol can also evaporate sometimes, but it mostly remains in the system and since it does not happen abruptly, the system does not suffer any damage.
 

XxTankerxX

2021-04-15 16:00:54
  • #4
Domestic hot water heat pump? The costs are much higher than with such an electric heating rod, aren’t they? That was my thought, yes. If you basically plan to cover the house, i.e. the own demand, with photovoltaics anyway, wouldn’t it be better to rely on an electric heating rod in summer? How much kWp of photovoltaics would you recommend for a single-family house of 170 m2 (+ basement) if it is only meant to cover the own demand?
 

nordanney

2021-04-15 16:24:15
  • #5
None, small photovoltaic systems only for own consumption. As large as possible. Everything else is uneconomical. So 10-15 kwpeak Initially yes. In use, definitely no. This is a very small heat pump, which is installed indoors and performs its work there. Maybe 1 kW power – from this, 4-5 kW heat output is generated (the heating rod is 4-5 times less efficient). Just google domestic hot water heat pump. Your electric heating rod is also called an instantaneous water heater by others. Then it might become clearer to you how efficient it is (although cheap to purchase).
 

XxTankerxX

2021-04-15 16:30:40
  • #6


Thanks for the info. I really have 0.0 knowledge in the heating sector. How much does such a small heat pump cost approximately?
 

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