Thermal Solar: Photovoltaic system for hot water production

  • Erstellt am 2016-04-07 21:29:07

T21150

2016-04-07 21:29:07
  • #1
Thread for relaxation – I do not want to start a fundamental discussion.

Steffi has the late shift and I have some peace and quiet.

I did a little calculating. At first I got carried away.
But it can be done more simply.
Since installation until today, the PV system has produced an average of 2.26 kWh per day.

I know the house and the heating and I know: Without a photovoltaic system I need about 4.5 kWh/day (via gas) for hot water production in our house. We are not exactly sparing with hot water. We both shower at least once daily and I have the energy-wasting habit of pre-rinsing dishes with hot water before they go into the dishwasher (because the machines don’t like dirt and break prematurely for that reason).

Thus, the solar coverage rate, purely mathematically in an approximate consumption estimate (in reality the calculation would be more complicated) is almost exactly 50%.
62% was calculated. That’s okay by me. In NRW the summer of 2015 was pure rain misery (compared to other federal states where the summer was very good and sunny).

Presumably, with “normal weather” around 60% would have come out, mathematically.

From my observations, however, the PV kWh don’t count quite so directly, a lot is lost.
I estimate 30% less effectiveness because a lot is also heated at the bottom in the storage tank, which initially brings nothing directly (stratified storage tank).

Overall, though, a good result, which surprised me a bit myself.

Conclusion:
- Heating drinking water does not cost much
- The PV delivers approximately the calculated proportion from the energy certificate, despite the east orientation. Mathematically. Real less, which is bearable.
- The investment for that: *look away*, tick it off.
- I would not invest the money anymore, but now I have it and don’t want to miss it anymore, since I like toys. And technically it’s nice because it’s so simple and fundamentally works (which many things nowadays no longer do).

Thorsten
 

T21150

2016-04-10 09:33:25
  • #2
Addendum. Yesterday the weather was generally usable, especially in the morning and into the afternoon. Almost the first time this year that the system ran properly.

The system produced 9.1 kWh (this is a calculated value from the system).
And it heated the water (300l) from 34 degrees in the morning to 49 degrees.

In autumn 15, maintenance was carried out, during which some parameters of the system were changed (flow behavior of fluid over temperature) - according to the latest specification from Buderus. I must say now: That really made a difference, the system is now running more efficiently.

I am satisfied with yesterday’s result.
 

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