Converting Solar Heat into electricity?

[Derek]

Cant remember where I read such a thing.  But if I have a solar device that gets 400 degrees, and then the outside temperature is 70 degrees, dont have have a potential difference to make electricity using a heatsink or something like that?  Let me know how to do that, cant find any info on that, or remember in the slightest bit how that is done.....

-Derek

[RogerAS]

Derek,

I think you're remembering the thermocouple. This device will work but they are VERY expensive per watt.

Look up solar stirlings, and new (relatively) approach to use the collected heat in a parabolic dish focused onto a stirling engine which in turn drives a generator. A big setup has just been started in S. Cal.

Hope this helps,

[Derek]

The stirling thing is where it spins, heats and cools and turns a DC motor or something.  Thats not really what I'm going for.  But every single thermocouple thing I'm looking at is for sensing temperatures, but I dont see anything about producing electricity.

I was thinking it was something along the lines of a heat sink, heat pump, or something that if one side of it was hotter than the other it would produce power.  What in the world was I looking at?

[TomW]

(blank)

[DamonHD]

http://en.wikipedia.org/wiki/Peltier-Seebeck_effect

In fact, I think it's the Seebeck effect that you're after (Peltier is the other way if I understand correctly: electricity into heat), but yes, I think it's very expensive per Watt.

If you have sunlight and you want electricity and you don't want moving parts, PV is your man / woman / small furry creature from Alpha Centauri I believe....

Rgds

Damon

[Derek]

I already have a solar oven that I am using for cooking that reached 400 degrees, which is way more than enough.  I was thinking of simply adding this idea to the oven to make a little electricity on the side.  =)  Where can I buy something for this?  I cant seem to figure out what it is I need....

[Mary B]

Do a search on Ebay for peltier. I picked up 2 350 watt (in cooling mode) peltiers for cheap.

[Derek]

I think that IS what I saw a good while back that had the heat sink on it!  Can get big ones for $20 on ebay it looks like.  If I got a big 370 watt one versus a 170 watt one, would I be able to get more voltage out of it?

[snowcrow]

The watts rating on the Peltiers are for power into the device, not out. I use one to cool the CCD chip in my telescope camera. (Cool to -35C for reducing camera noise.) I just found my spare one, and put some fire to it with a lighter. It leveled off at .56 volt for a 35 watt rated Peltier. Sorry Derek, they're great for heating and cooling but a very poor choose for a power source!

[Derek]

What I'm wondering is if the bigger 350 watt rated type will have more of a power output than a smaller watt type like you have.  Commen sense would say probably so since its bigger, but hard to say.  I think using a heat sink for absorbing the most heat onto one side is going to be better as well.  And still, a lighter wont heat the entire thing equally to 400 degrees probably.

Anyone know if a higher watt rating would result in a higher electrical output in a Peltier?

[DamonHD]

You might get more power/energy, but not necessarily a higher voltage.  Depends what you want.

Rgds

Damon

[ghurd]

There are 2 types of Peltier's.

They are not the same.

One type is for heat transfer.

One is type for power generation.

There is a large commercially produced device that is propane (and other) powered device for DC power using Peltiers.

There is a small commercially produced lantern powered emergency radio using Peltiers.

Etc.

G-