PV Gap

Ron Said:

Is a Fresnel lens the best way to heat large amounts of water for a solar heating system,if not what is?

We Answered:

What is best depends on what you want. How hot, how much water, how much sun (where you live), how much it costs and how much space on your roof and what sort of regulations you may need to comply with.

The simplest and cheapest for a build it yourself system may use black polyethylene pipe. This can work well in the tropics. By placing the tank above the absorption panel the water moves by convection currents, and no pump or controller is needed. Commercial units use blackened plastic or metal tubes behind glass. In colder zones they may be glass tubes in a vacuum. Look around what others use in your region. You will need a consultant anyway (perhaps a supplier) to size the system using their own local knowledge, and knowledge about their system. The important questions are more likely how it behaves in a storm, with snow, how long it lasts, etc. Most people buy on price too.

As you have an underground tank you need pumps and a control system to circulate the water, as that is how they heat the water, recirculating it through the tank and panel, adding a bit of heat each time.

Systems that use focusing will most likely need to have a tracking controller. The result is that the energy obtained over the day is maximised, as the collector is always pointed directly at the sun. What kind of focusing you use depends on availability in your region, regulations etc. A highly focused beam of sunlight is hazardous, and unnecessary for water heating. The energy obtained is per unit area of the incident sunlight so focusing increases the temperature not the energy. Tracking the sun alignment increases the energy over time (daily basis).

Eva Said:

What is the greatest source of heat in our solar system?

We Answered:

Capitol Hill.

There's enough hot gasses emitted from Congress that can be harness to solve global energy problems for the next millennium.


If global warming is truly happening because of man's careless actions then those who are concern about earth's destruction has a much bigger fish to fry than just the United States alone.

China, India & Brazil would be largest culprit.

They have the largest populations among the industrialized countries in the world with minimal or NO enviromental regulatory enforcements in place.

They along with other emerging third world nations polute the earth's enviroment with man made toxics.

We don't see global warming activists policing their actions anywhere else.

If global warming is truly a dangerous global ending catastrophe in the making then go out and stop the rest of the world from poluting.