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Solar Thermal vs. Photovoltaic

It is important to understand that solar thermal technology can be used to create electricity by means of a stirling engine. This technology is not the same as solar panel, or photovoltaic technology. Solar thermal electric energy generation concentrates the light from the sun to create heat, and that heat is used to run a sterling engine, which turns a generator to make electricity. The working fluid that is heated by the concentrated sunlight can be a liquid or gas. Different working fluids include water, oil, salts, air, nitrogen and helium. Different engine types include steam engines, gas turbines, stirling engines etc. All of these engines can be quite efficient, often between 30% and 40%, and are capable of producing 10’s to 100’s of megawatts of power.

Photovoltaic or PV energy conversion on the other hand, directly converts the sun’s light into electricity. This means that solar panels are only effective during daylight hours because storing electricity is not a particularly efficient process. Heat storage is a far easier and efficient method, which is what makes solar thermal so attractive for large-scale energy production. Especially a good option for Wineries, breweries, Meat packing plants and any large scale consumption of hot water. Heat can be stored during the day and then converted into electricity at night. Solar thermal plants that have storage capacities can drastically improve both the economics and dispatch ability of solar electricity. Solar thermal reduces energy dependance by providing heat. It is the best option for swimming pools as an example by providing hot water and eliminating necessity for energy consumption.

Solar thermal power is the best option for energy independence. Efficiency is much higher allowing you to use up to 70% of the sun’s energy with¬† a thermal solar collector. Using a PV collector, sunlight-to-electricity conversion rates average about 12% only. You can also look at it in terms of area. The energy available from the sun is about 1kw per square meter. This is equivalent to 3400 BTU/hr/square meter. Therefore, if you can get 70% efficienty using a solar thermal collector, you would only need approximately 42 square meters to generate 100,000 BTU/hr. or the amount of heat generated by a typical gas furnace.

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