Solar Panel//Underside//Thermoelectric
 

I have seen this suggested idea..

This is fairly straight forward idea to take solar panel and on the underside of panel mount thermoelectric square pads. I have/ am considering doing this just for the sake of trial if nothing else.... Now which size solar panel and how many and which size thermoelectric generators....solar PV meet TEG

TEGS are inefficient under optimal conditions, and even more so by covering them with a solar panel rather than a heat sink. The bottom side would need to dissipate heat somehow if the solar side is providing the heat.

It would be interesting to see if this actually produces more energy or less. The TEGs will insulate the back of the panel to some degree which will reduce the solar cell efficiency.

It would have to be a thermal solar to even begin to make sense even then PV is more efficient cost wise.
The only benefit a teg would have over solar is it could work anytime you needed it like the middle of the night, powering it with say a coal or wood fire.

I'd like to put a 3-4x24-32ft collector for heating air on the roof of my 35ft trailer. Partially for the roof insulation, as well as space heating.

When I heard Tesla rents solar installs for $50/ month, I thought — replace the black body and glazing with PV panels.

I wouldn't waste my time with a tesla rental system.

I doubt it would ever happen, but it made me have the thought. About a single row of panels connected end-to-end.

It wouldn't save money, my bill runs $40-80/month.

A roof top rig made with used poly panels and used inverter could run you 70 cents a watt if you do it your self.

Since polycarbonate passed 90+% of light, might it make sense to glaze over the panels and pass air above and/or below them?

I'm not cutting holes in the roof, but if I was building from scratch it'd be a trolley-top, with curved solar panels on top with 23-window bus roof lights using Dodge Caravan frameless hinges and latches. The ribs would be aluminum I-channel with dimple-died lightening holes.

Tempered glass, polycrystalline cells.
Are you talking about vehicle installls?

The situation is a S(outhern) P(acific) Airstream grounded on the county tax roles so [shrug]. There exist four 14" roof vents. Air and conduit in and out there.

The pipe dream could be anything. A Dutch canal houseboat? I just like trolley-tops.

I think rather than TEGs I would line the back of the panels with some type of water or glycol carrying device. Maybe solid, maybe a bladder that could be attached across the back. This way the panels themselves would become more efficient since the liquid would cool the panels and one would be getting hot water out of the deal at the same time. Seems like I read about someone trying this years ago but I can't recall the outcome. Certainly there would be a few issues to overcome. You'd have to consider the extra weight due to the water and figure out how to handle the ever present possiblity of leaks and of course what to do in the winter for those of you that have that, but I believe this would be a viable use of the back side of PV panels.Maybe I'll play with this next summer.
JJ

In my case there are three 14" square roof vents, with a whole house fan on the center one. So it can suck up on the center one and blow down on the two ends. It may not be as efficient but it works with what's there.

I think that's a brilliant idea for a grounded TT with holes in the roof already. Maybe a black painted box with recycled sliding glass door cartridges arranged as a pitched roof, with 6" metal ducting going lengthways to a plenum on each end and the middle. Insulate the box with 2" foam, paint the tubes and background black.
I think it would cook you quite nicely on the shoulder seasons in the PNW, and act as a bit of insulation in the dark of night when you close it all off.

Thanks. The plan is for metal 2x4 channel with 2" of insulation. But instead of tempered glass doors, I'd probably spring for corrugated clear plastic over curved ribs with the corrugations running crosswise.

Thermoelectric
 

Question /Discussion

Preface
Thermoelectric squares come in a couple of different sized dimensions available on ebay and etc. That being stated...

The curious question being is the following .. Could a direct application on a vehicle headliner(removed to expose metal skin provide a space for placement and there in make a setup for peltier cooling side toward personal space cooling

Sure it would work... terribly. You've specified no objective though, so how are we to evaluate the question?

TEGs are like 5% efficient if you've set them up correctly (lots of heating and cooling surface area on both sides). AC is generally over 100% efficient by comparison.

I once bought a peltier cooler so I could experiment with overclocking my CPU. Even with a triple fan massive heatsink, it couldn't seem to dissipate heat fast enough to shed the minor amount of heat generated by the CPU plus the massive amount generated by the peltier. That, and there were concerns about condensation (you want water dripping from your headliner?).

So, you could mount peltiers to the roof, but it wouldn't have enough surface area to even achieve 5% efficiency, and you'd be rained on by condensation. The roof would turn into a giant frying pan before it was able to cool the cabin reasonably.

The only practical use for TEGs in a car would either be:
- stuck to the exhaust behind the last cat with a big flat copper plate on the cool side in the airflow, or
- a 2-way coolant TEG harvesting the heat difference between coolant flowing from the engine to the radiator and the return flow.
I looked into the latter but it isn't cost effective at several $ per W.

Solid state cooling takes about 4x as much power as modern refrigeration to cool something.
The only place it makes sense is in really tiny applications where adding refrigeration isn't practical.

interior driver
 

FYI
application of driver side interior spot cooling....Texas is a little warmer than the PNW

If you attach the cold side to yourself, and use a water cooled heatsink to pump away the heat it might work.

MIT has a paper on this, where they had a bulky watch sized device that would occasionally cool the inside of your wrist. Che chilling sensation there made your body think that it was cold.