The Breakroom > The Water Cooler

Low voltage DC solar heating pump from europe?

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PekkaNF:
At this latitude tank is inside, panels are at the roof there is least 300 mm of insulation against the winter cold and heat transfer fluid must withstand closer to -40C.....so...no thermosiphon...actually shut of valves are needed to prevent unwanted thermosiphon during the coldest winter months....but yes...it will work least 6 months a year.

vtsteam:
I don't know why photovoltaic panels aren't fitted with backside heat exchangers and insulation since most of the energy hitting a them is wasted as heat..... estimated at 80%+ or 1kW/sq M in direct sun. Cogeneration is a big topic for DIY engine driven generators, why not photocells? Why should one have to install both types as separate panels taking up additional space and materials?

Well as long as we're going outside the box, add thermoelectric modules between the cells and the heat exchanger since they work on a delta T for maybe another 3% sunlight/electrical conversion efficiency. and use a liquid Stirling engine pump for circulation if thermosiphoning isn't possible.

WeldingRod:
Note that a regular relay will not survive switching 200+ Volts DC..

Sent from my SM-G715A using Tapatalk

vtsteam:
Pekka,
March brand pumps are available in Germany:
https://www.marchpump.com/en-de/pumps/

The 809 and 815 pumps come in bronze and 12v and 24V, example:
https://pumpbiz.com/march-bronze-circ-pump-809-br-24v-dc-brush#

They have less expensive pumps using plastic, but seemingly high quality.

PekkaNF:
Thank you all!


--- Quote from: vtsteam on July 19, 2022, 12:17:27 PM ---I don't know why photovoltaic panels aren't fitted with backside heat exchangers and insulation since most of the energy hitting a them is wasted as heat..... estimated at 80%+ or 1kW/sq M in direct sun. Cogeneration is a big topic for DIY engine driven generators, why not photocells? Why should one have to install both types as separate panels taking up additional space and materials?

Well as long as we're going outside the box, add thermoelectric modules between the cells and the heat exchanger since they work on a delta T for maybe another 3% sunlight/electrical conversion efficiency. and use a liquid Stirling engine pump for circulation if thermosiphoning isn't possible.

--- End quote ---

I have seen some studies of cooling the PV panel and also using the cooling energy for heating. I went two years ago to Biosphere II, AZ ant they had outside few PV panels elevated little off from the ground. The shade was used grow some plants who in turn kept panels cooler.  I heard that some panel plantations in very arid climate attracted plant undergrow due to more favorable microclimate. Apparently panels here produce pretty well early on spring when ambient temperature is cold but sun shines from clear sky.

I saw one study about liquid cooling of the PV panel back, there was some complications on chemistry and physical structure....nothing show stopper, but needed some special encapsulation to keep the coolant of the traditional PV-parts...voltages get easily few hundred volts across the panel string, there is another consideration.


--- Quote from: WeldingRod on July 19, 2022, 04:54:55 PM ---Note that a regular relay will not survive switching 200+ Volts DC..

Sent from my SM-G715A using Tapatalk

--- End quote ---
Noted. AC and DC is ibit different when it comes to contactors. Here the current would be pretty low (10-16A absolute max) and resistive load is pretty well behaved. Most likely electronic solution would be eventually better choice, because PV panels are not a linear power supply and something should change (like load) to get best out of them. Here it pays off to use excessive energy for heating instead of pushing back to network. One solution would be "diverter".
https://www.solarpanelprices.co.uk/articles/solar-panels/solar-pv-diverter-explained/



--- Quote from: vtsteam on July 19, 2022, 05:51:12 PM ---Pekka,
March brand pumps are available in Germany:
https://www.marchpump.com/en-de/pumps/

The 809 and 815 pumps come in bronze and 12v and 24V, example:
https://pumpbiz.com/march-bronze-circ-pump-809-br-24v-dc-brush#

They have less expensive pumps using plastic, but seemingly high quality.

--- End quote ---

That looks pretty good. I'll follow that lead and see what cost structure it would produce.

Thank you,
Pekka

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