Solar Thermal Collector
Converting Sun Radiation
to Heat

Solar thermal collectors, also known as solar thermal panels are used to heat water. The two main application areas for solar thermal panels are solar hot water heaters and solar swimming pool heaters.

The Sun is Earth Energy Source

The Sun is a remote enormous radiation source. The Sun is in essence a huge fusion reactor; it is a very big ball of hot gases mass that is pulled in by the Sun own gravity, producing at its center a combination of very high pressure and very high temperature. The pressure and the temperature are sufficient to combine light Hydrogen atoms into heavier Helium atoms. The mass of the Hydrogen atoms before the combination is slightly more than the mass of the resultant Helium atom. The “lost” mass is converted into energy in the form of radiation. A destructive demonstration of the fusion process is the H-Bomb. Experiments to generate here on Earth a “micro Sun” that will generate energy in a controlled fusion reactor were started in the 1970s, but it will take many years until these experiments will lead to commercial implementations. Going back to the Sun, the generated radiation goes from the center of the Sun to its surface and from there through space the radiation spreads to all directions. A tiny fraction reaches Earth; The Sun radiation that reaches Earth in one 24 hours day is more than the energy used by all Earth population over one year. This process started billions of years ago and the Sun will deplete its Hydrogen billions of years from now.

The sun is the major energy source for planet Earth. We use Sun energy in the following manners:

• Trees, grass and other green plants use photosynthesis to produce bio-mass from CO2, minerals in the soil and Sun radiation. They serve as a food source (energy) for animals and can be used to produce bio-fuel

• Fossils (coal, crude oil) are the products of plants and animals that lived millions of year ago and were deposited and buried under high pressure

• Solar Thermal Collectors – converting Sun radiation to Heat using the greenhouse effect

• Home Solar Electricity and larger scale Solar Power Plants

• The climate machine is driven by Sun radiation heating differently the different regions of Earth land and oceans; these can be used by power plants “riding on waves”, hydroelectric power plants and wind energy

Solar Thermal versus Solar Electricity

There are two major methods to convert Sun Radiation into a useful renewable energy source

• Solar Thermal Collectors – convert Sun radiation into Heat, to solar thermal hot water and for space heating
• Solar Electricity – using the photovoltaic effect for residential solar electricity

Large scale Solar Power plants use concentrated radiation (using mirrors or lenses) to steam water and run steam turbines. Another method is to use concentrated solar to generate more electricity from a given size of the expensive solar panels

Due to the higher cost of Solar Electricity compared to Solar Thermal for residential applications, investment in Solar Thermal is returned much faster than the investment in Solar Electricity