Air space or liquid

[Mike Gibson]

I have built my solar panels with about an 1/8'' air space between the cells and top plate. I read some where that you can fill that space with a liquid to help keeep the heat down. I am wondering if i should use water or a mineral spiret of some kind?

[Paul Bailey]

definately not water. I believe some of the do it yourself panel builders were using some form of very light oil/ or mineral oil for this air space. The intent was to elimimate condensation and build up of who knows what might grow in this space. Not to diffuse heat buildup.Commercial manufactured panels are bonded tight usually to a layer of PVA in a vacuum so they do not have this problem. Also remember that some PV panels Love the heat but most all do not.. I'm sure somebody here will Know so stay tuned. Paul

[Frank Flynn]

I have heard of something like this - not to fill the space between the cells and the top plate. I imagine putting a cell that was not designed for it under water (or oil) would certainly shorten it's life; if not kill it imeadately.

But I have heard of a manufacture that mounts the cells on a solar hot water panel - and the idea is most definately to remove heat from the cells and transferr it to the domestic hot water. The PV cell on a hot sunny day can get quite hot but this design limits the temp to 140 - 160 for a typical home. PV's will produce less energy on hot days then they do on cool days with the same sunshine; I believe it can be up to 10% less energy when they are hot.

This was a panel manufactured for this purpous and the cells and the water never come in contact with each other. Because the solar cells are only ~5% efficent there's pleanty of heat energy for the water.

I have searched but can't find this product - which does make me a bit suspicious that this is one of those things that are true but doesn't really make that much diffference in practice.

Here is a somewhat technical article talking about cooling you PV's with water and using that for hot water.

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000128000002000146000001&idtype=cvips&gifs=yes

[Joe Blake]

If the concern is about heat, have you considered sneaking a little cooling fan in there somewhere? The computer-type ones (not weatheproof) draw something like 2.6 watts. If your panel produces 64 watts and you lose 10%, that's 6.4 watts, so theoretically a fan would give you UP TO a net gain to 3.8 watts.

Then you could go for those "car window" fans that have their own independent photovoltaic cells. The brighter the sun the faster they run. And depending how you mount them, they're fairly weather resistant.

Something like this.

http://www.ciao.co.uk/Auto_Cool_Solar_Car_Vent__Review_5641845

[Mike Gibson]

I hadn't thought about using the car or puttter fans. That sounds like an idea that is worth giving a try.Also i haven't finished the sealing part yet I think i will leave holes in the bottem, maybe from toothpicks or screwers like for shiskabob.

[Rob Beckers]

Hi Mike,

Could you write a bit more about how one makes DIY photovoltaic panels? I really have no idea this could be done at all. There's a source (other than wholesale) for just the silicon cells? What are the prices like? Pictures?

-Rob-

[Mike Gibson]

The panels are rather easy to make. I have got all my cells from Ebay. You can get the cells, Tined wire and i saw just the panel itself W/O cells. I have 4 panels laying on my office floor now waiting to be added to the aray. I have 5 already put up on my shop. I am still in the learning stages. I wanted to do windmills but not enough wind in MIssissippi pleanty of sun though. Try this web sight (http://www.fieldlines.com) or this one http://www.builditsolar.com/ Both are very good but i think you will like the Fieldlines better . It is about all alternative energy Wind, solar and hydro with some very informed people. If i can help any at all let me know. One of the sellers on Ebay is on fieldlines regular. O the fieldlines is also called (the Otherpower .com)

[Frank Flynn]

OK I spoke to a frined of mine who does PV instlations and I asked him about this. His answer was it's true that heat will decrease the efficiency but Domestic Hot water is not a good source to cool the PV panels because it's already too hot. He said if you were heating a pool where the water temp might be 80F this would help. But he doesn't usually do this - just leave a way for air to cool them, they'll be fine.

So - it's true but makes little difference.