PV Gap

Leroy Said:

how do you make a solar powered water heater?

We Answered:

Solar powered as in photoelectric cells or solar powered as in "use solar radiation to heat water"?

For the solar radiation answer, yes. A professor when I was in school used to have a solar-powered {fill in the blank} contest each year. Some years it was hotdog cookers, one year was a water heater. The trick is to capture as much heat as possible. Common tricks are:
1) reflectors to focus the light on the thing to be heated - aluminum foil is a decent reflector, although it's hard to keep it from crinkling and scattering some of the radiation.
2) black surfaces, since black bodies absorb more radiation heat energy - black pans can be a good thing to use for this.
3) Greenhouse effect - by placing a glass dome (mixing bowl) over the thing to be heated, you allow radiation energy in, but it has trouble leaving... plus it has the added bonus of reducing heat loss to convection... you get a nice, stagnant layer of air over the thing being heated... stagnant air is a poor conductor of heat.

Those are three very common things that you can do to maximize the amount of solar radiation available for heating the water.

The trick is getting enough energy to heat a sufficient amount of water... so, I guess he real question is how much water you want to heat and how fast you want to heat it.