My biggest disappointment about my 200KW (commercial scale) solar system.

woodgeek said:

Semipro said:

It seems there's a opportunity here for combining PV with solar hot water supply. Heat or preheat your DMH while cooling the PV panels. You still need DHW when the weather it hot.

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Actually that's why you see very few hybrid systems--the PV doesn't work when its too hot, the thermal panel only works when its very hot.

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I'm probably not being clear... or maybe I am and I just don't understand.

Why not use the PVs as water pre-heaters. If unheated water (in our case at 50 degrees F) was allowed to cool the PVs from the backside the heated water, though maybe not hot enough for use, could then go on to whatever you use as a water heater whether solar or otherwise.

Edit: took the time to do a short search and found this and other links:
http://news.discovery.com/tech/hybr...t-water-electricity-110504.html#view-comments

Now I'm wondering how a do it yourselfer could do it.

firemedic said:

Woodchip, couldn’t you just catch early sun on one side and late day sun on the other?

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That would be double the panels...... they are quite expensive here, even for diy projects like I'm thinking of......

I have a similar facing roof and I figured the PV panels could be positioned like that to get early day light on one side and late on the other. I have a contractor coming today to look at it. Maybe he will have some recommendations that I can share with you. I figured that the panels will maybe last longer if they are not on the most optimal aspect.

Does anyone know if this is plausible reasoning? Or, is the lifespan based on just age and not on the amount of sun time?

Semipro; I understood your idea and it made good sense to me. I wonder if the little pvc lines that they run in radiant heating applications could be used for cooling the back of the PV panels? I bet that there are significant differences in performance in heat just based on design and the materials that the panels are made out of.

Would this product help prevent the efficiency losses from heat? http://solutions.3m.com/wps/portal/3M/en_US/Scotchshield/Film_Backsheets/

firemedic said:

Would this product help prevent the efficiency losses from heat? http://solutions.3m.com/wps/portal/3M/en_US/Scotchshield/Film_Backsheets/

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This is already incorporated into the pv module, it's the back sheet. There is a company that makes a thermal unit that attaches behind the back sheet. Sundrum. I do not have any experience with it but it looks interesting http://www.sundrumsolar.com