Solar heating panels

[medvampire]

Getting ready to set up some solar heating panels and was wondering.
Temporary going to lay them on the ground would it be better to lay black plastic, tar paper, or just bare ground under them?
Steve

[CarlD]

Just bare ground is fine. The heat bakes through so you don't get that slimey, wormey, bug-filled muck that you normally get from something on the ground. You get dead grass either way, but it won't be disgusting when you lift the panels up--it will be dry and baked. It will heat the ground around it, and that ground will go on heating the water after the sun passes, passing it back to the panel. Done this a couple of times.

[matt4x4]

I used my useless winter cover as a barrier under my panels and landscape edging around the perimeter, then spread 3/4" pea gravel around and between the panels - gives it a nice finished look and I don't have to deal with Grass/weeds growing up around the panels.

[Poconos]

After several years of having my homebrew array laying on tarpaper I gave up. It doesn't last. Had to replace every year. Bought some rolled roofing this Spring and so far shows no sign of deterioration. Tarpaper would have been pretty ratty by now. Got the cheapest stuff I could find at Home Depot. Time will tell.
Al

[medvampire]

Thanks for the answers. I am going to build racks in the spring and plan to use rolled roofing to underlay the panels.
Steve

[matt4x4]

If you're going to build racks for your panels, I presume you will use wood - possibly PT. In this case, I don't think any underlay is needed, it will certainly NOT help with heat gain, the only possible extra heat gain I could see is if you were to use something reflective like aluminum foil or the silver foil covered foam boards used in house construction. Reason being, the black underlay would actually absorb heat that's allready in your panels, where the reflective would bounce the heat trying to push through the panels right back at them.

The only reasons I used my black winter cover as underlay on the ground was to keep the weeds down and that I had it kicking around and it saved me from buying tons of landscape fabric which is also black, however, for a raised install I would not use it.