On a clear day, a single square meter of surface directly facing the sun is offered energy at a rate of approximately one kilowatt per hour. So if you had a collector surface of ten by twenty feet, you could be receiving up to 18 kilowatts per hour – how many homes use that much?

   The kicker lies in just how much of all this you are able to accept. If you're collecting it in the form of heat you might be able to retrieve better than eighty percent. If it's electricity you're after, be happy with about ten percent. Another problem is that the sun spends its days continually changing position, so unless you are mechanically tracking it, you are only briefly optimum.

   In spite of all this, the sun remains an incredible resource, and even on an overcast day you may still be graced with about twenty percent of its clear day offering.

   This one is great for daytime heating, and can be cheap and easy to apply.

   I have enjoyed the luxury of a quiet town from the perspective of a 14-foot diameter pool 90 degree water. Solar heating it was almost as easy as getting up for an hour or so at 3:00 am to enjoy the solitude.

   A couple varieties: One is a sturdy sheet metal version, and the other is a surprisingly high performing contraption of cardboard, aluminum foil and glass.

   The module defined here could be to the solar industry what the steam engine was to the industrial revolution.