I am however concerned about freezing problems, more due to glued joints at the ABS pipe at the top and bottom of an assembled panel bursting. I plan to have a large holding tank of water used directly with the panels without a heat exchanger to the holding tank so I’m not too interested in using a bunch of anti-freeze. I am planning to build a drainback system using these panels, and just painting them black.

I also saw that polypropylene does not tolerate UV light well and will become brittle and break after long exposure. Coroplast can however be made special order with a UV absorber mixed in with the polypropylene. I am getting some regular Coroplast from a local sign shop that does not have the UV protection, so I’m looking into paints that absorb the UV. If the prototype works well I’ll look into getting UV protected Coroplast for additional panels.

I’d like to use this design to heat a hot tub (in addition to a bio-gas powered water heater: read more about biogas here: http://solarcities.blogspot.com/)

I’m a bit worried about chemicals leaching into the water. I’m not planning on drinking the hot tub water, but are there any issues with exposure to the plastic chemicals?

I came across your site a few months back while I was prototyping my own plastic thermal panel. I think plastic solar panels have the potential to completely revolutionize the industry by lowering the cost. However, you hit on the problem I was working on:

“because the whole collector is made of plastic, it is important that the temperature doesn’t get too high or it will soften and possibly spring a leak. 80 degrees C (176 degrees F) is about the limit. Don’t think it can get that hot? Think again. …Therefore this may not be a practical design for residential installation”

Well, I put some thought into it and I think I have a solution that will prevent the panel from overheating (the panel turns itself off when no water is flowing), which means that it can be insulated and hopefully compete with commercial systems, only at 20% the cost. I think the efficiency may also end up being higher then commercial systems. I built a prototype:

http://www.particlepanels.com

…and posted a video of it to youtube.

I just wanted to give you a big thanks for your website and the work you are doing. Its people like you that are going to save this planet.

Blue Skies,

Alex

I plan on making an insulated sand-box w/ paving blocks as the top surface. This way I will always know the walking surface is in contact with the sand. I will insulate 4 sides and bottom.
As for the location of the collecter vs sandbox….I guess I will need to use a pump

Any idea if your design (as posted and unmodified) will be able to fend-off freezing inside a 12 x 12 hoophouse? I’m not sure of all the math aspects of air volume/heat dissipation…etc.

2) Unless you can locate your collectors at least a couple feet lower in elevation than the sand bed, you’ll need to use a pump to circulate the water.

1) I plan to use some form of thermal mass in the floor to hold and maintain heat (maybe 6″ sandbed with finned-pipe throughout). Should I run my pipe direct from the collector to the sand-bed and then to the storage container, or from the collector to the storage container THEN my sandbed?

2) Since I’m cheap and dont want to run a pump all the time (allowing syphon to do the work), will I be able to install this system to heat a sand bed?

Any and all help is welcome. You seem to really know your stuff

Well, just one concern. I am worried about what Eric said about sanitation. Anybody with any ideas on how to make this system “anti-bacterial”, “anti-fungal”…just safer.

The idea is less materials, lower cost, less leaks, with the air taking up all the space for heating but you move that heat with the fan so it’s like collecting with long tubes over the same area. It might be as simple as painting the wood inside black or putting a black trash bag in there. Maybe convection would move the air, but I think a fan would raise the efficiency and you could run that with a small solar panel.

I am interested to add a solar water heater on top of our camper. Since I also live in vancouver, BC would it be possible to meet with you and see your prototype? Where I grew up in Israel it is very popular (mandatory actually…) but those systems are too heavy and not mobile. I liked your use of plastic however if you check carefully, the acid rain might corrode your plastic so a glass cover is recommended. I also suggest you warn people not to drink those water!

Best regards

Alon Newton – Vancouver, BC

Regarding the idea of the shallow tank of water with black metal sheet “floating” on it… An even simpler design is to paint the bottom of the tank black, or use a black liner of some sort. It does not need to be a good conductor since the absorbing surface is in direct contact with the water being heated. The only issue with this design is that water may condense on the underside of the glazing reducing the amount of radiation transmitted.