ECN Forum Forums General Topics of the Trade General Discussion Area Building photocells and self generating electric

Just ran across an ad where a photocell panel was advertised for $100. It didn't give any specifics about how much juice it would put out, but got me thinking about how hard it would be to make one. I think it takes silicon and phosphorous crystals, or perhaps a lazer.
Wondered if anyone has thought about, or does generate their own electricity. What method they use, I read a little a long time ago about solar cells, batteries, windmills, and a guy who lived on a cattle farm that got his fuel to run generators and tracters off the methane he produced by putting cow patties in a silo.
Anyone thinking or have any practical experience along these lines?

Fifty to a hundred million bucks of semiconductor processing equipment should get you going on that for a small-scale operation. Getting a PhD in semiconductor physics would also be useful...

In all seriousness, it's really, really hard to make solar cells. You need a cleanroom facility (those cost many millions of dollars), and then you need very precise, expensive equipment to do the processing. For example, the diffusion tubes that diffuse the various dopants into the silicon wafer have to hold everything at something like 1000C (that's just a ballpark number) and keep it there with no more than 1/10 of a degree variation. You don't do that with a kitchen stove or a pottery kiln--you need specialized equipment that sells for millions of dollars a copy.

And then, it takes a HUGE amount of knowledge to be able to get the silicon process right. You're generally talking about a whole team of people with PhDs and years of experience under their belts.

The moral of this story: Don't try this at home!

Making electricity is probably one of the hardest DIY tricks.
It is hard to compete with a utility. The Germans were spending something like 55 eurocents per KWH in a commercial PV setup the last time I saw an article on it. Any hobby setup will undoubtedly be a lot more expensive.
The thing that you can do with solar, pretty cheap is to just trap the heat and do something with that. Domestic hot water seems to work well. Pool heating is my big solar project. It works pretty well. I am down right now because my collectors were on the part of the house I tore down for the addition but I will have them back up soon, maybe this week. The innovation comes with the controller. The trick is to make it as simple as possible and still have good functionality

Look at nanosolar.com

There you can see the $$$$$$$$$ required to be a player.

For the contractor, it should be more than enough to install listed PV equipment. That'll keep you fully occupied.

As for patching together PV battery chargers... it's totally uneconomic. The cost per watt is horrific.

Naw, nobody does wafers anymore outside of aerospace and other high-dollar applications, and even a lowly class 1000 cleanroom would be fine; it's all about amorphous silicon now, and it can be made MUCH more cheaply. All you need is a a source of semiconductor-grade glass and series of car-sized vacuum chambers to set up the various sputtering and doping processes. Then you, too, can be a solar panel manufacturer!

Actually, just running black-painted PEX through a black painted box would work pretty good for heating water, and that hot water could be used to power a small heat engine. This would be a more practical method. Alternately, sun-tracking parabolic mirrors could be used to concentrate solar energy on a steam generator, which could drive a small steam engine.

I think a DIY wind turbine might be an easier project.

From what I hear the obvious answer, car alternators, is not a good plan for alternative energy projects. They are supposed to be fairly inefficient. The only good thing is they can be had cheaply if you have access to junked cars.

Not to mention that they are typical wound for only 12 V. If the intent is to power up 120 V devices, inverters like higher input voltages like 48 or 60 V.

Larry C

I think car alternators can put out 120v at about 3600 RPM with the right regulator but spinning one that fast is not likely very often in a wind system. If you had falling water you could probably make it happen with the right gearing.