JUL 05

The SolarWall PV/T product, created by Conserval Engineering has been available for a while now, and has been installed at Concordia University in Quebec.

http://solarwall.com/en/home.php

Please investigate these and tell us why they are not being deployed to collect more of the sun's energy.

to Mr. Gumbs,

It does not collect more energy. Every modules has a loss by cell heating (every 1 C degree, %0,5 loss) Hybrid panels decrease this loss by cooling down the cells. It seems that the advantage of Volther comparing with others is that you can use this hot water as well for heating house and the cooling down performance is good.

My question is in regard to the cost, does the extra cost in the combined system made up for in the hot water production? Although any added hot water into the system that isn't heated by natural gas would obviously reduce the amount of gas burned...

Every little bit counts, love when two great sustainable technologies meet and fall in love, ha ha...

www.greencollarenvironmentalist.com

I believe this has been tried before, typically with poor results from pipe degradation well before the PV cells age. Also, it's near impossible to get UL certification in the US, as you're putting high voltage electrical generation right next to water. You can't put a non GFCI outlet near a faucet - imagine the dangers of running a 60 amp line right next to your drinking water.

wonder if there could be some ground storage system, summer and winter making a mini geothermal situation storing hot water for heating or bringing cooled water up?

@ Steve A., your drinking water will not flow trough the pipes, heat will be transfered by a heat exchanger. Seems to me that these are very easy to ground.

To heat domestic hot water to at least ~50C / 122F (to prevent Legionnaires' disease) via a heat exchanger, the hot water coming off the back of the PV/T modules would have to be around ~60C / 140F, and therefore the PV module temperatures would need to be at least ~70C / 158F. In other words, to get hot enough water, the water flow needs to be carefully regulated to allow to the domestic hot water supply to be hot enough.

In the summertime, keeping the panels at ~70C / 158F may be about the same as running the panels on an open rack. In the wintertime, the panels have to be heated to similar temperatures, i.e. seriously restrict the water flows, to get the output temperatures hot enough. The temperature differentials have to be more extreme if the inlet water is quite cold. And the hotter the panel, the less PV electricity is produced.

For heating of swimming pools, these systems may prove to be very effective. The cooler temperatures of a spa or swimming pool allows for the PV modules to run at lower temperatures, which allows for lower PV cell temperatures and more electric power.

In short, there is a trade off to such a system. To get the thermal temperatures hot enough for heat exchanging, the electrical output will be reduced. This may not be an issue as long as the salesmen state this upfront. And as already been previously mentioned, I would be nervous in guaranteeing any water-based plumbed system to truly last 30 years.

An open loop system, using fresh, cold tap water would consume a huge amount of water in order to maintain cool surface temps on the panels.

A closed loop system would require a huge reservoir to avoid overheating. The hotter your water reservoir gets, the less effective the system will be. The smaller your storage capacity is, the faster it will heat up. This is no problem if you have a swimming pool (or a pond) but these aren't often readily available.

This system seems like a great concept, but it is unlikely that this could ever prove cost effective for any commercial applications.

@SteveA
PV solar creates low voltage. So I wouldn't think it would be much danger to keep it close to water. Besides of that most solar thermal installations use glycol or similar products instead of water to transport and transfer heat.

Years ago, I was involved in emerging solar work using a refrigerant system that used the outside coil as an evaporator and the inside coil as the condensor which exchanged that heat into the domestic water system via a circular pump. It actually worked very weel even in a northern climate, as there was always heat available above the evaporator temperature. Seems that technology along with PV would be an ideal combo, since it will keep the PV cooler than water or glycol, require less volume and have a good return on the electirc for generating the refrigeration. That was a reciprocating system and standard refrigerant, but a high temp refrigerant with a centrifugal compressor would take less power and be a little more efficient.

Anyway, my two cents. Now, someone go make a billion dollars on my suggestion! :-)