# African solar systems part 3: concentrated solar power

The amount of energy calculated in part 2 is a tremendous amount of energy, far more that can be reasonably used. The trick is to get it into usable form. Right now there are dozens, if not hundreds, of new companies investing in technology and systems to provide solar energy to Africa. Devices that convert solar energy into usable energy generally fall into two classes. First, there are photo-voltaic devices which directly convert sunlight into electricity. If we are thinking only of cell phones or other electronic devices, photo-voltaic cells provide direct electric power at a reasonable cost. However, they have drawbacks. If you need other forms of energy, for example heat for cooking, a photo-voltaic system must perform two conversions - sunlight to electricity and then electricity to heat. This results in a loss of efficiency. Additionally, photo-voltaic systems cannot store large amounts of energy and therefore stop working after the sun goes down.

The second conversion method goes by the name of concentrated solar power (CSP) - you concentrate the sun's energy to heat up a fluid of some sort. You then transport that fluid to another location and use the fluid heat to generate electricity through a steam turbine, cook, or provide ambient heat. Alternatively, you can store the fluid heat in a storage tank. A CSP system has two advantages - it generates heat directly so can be more efficient for a combined heat and power system, and since it can store heat it can provide power and heat after sunset. However, it also has to do a double conversion of energy to get electricity, so if the demand for electricity is higher then the demand for heat a CSP system is not as cost-efficient.

Note by David Mattingly
7 years, 4 months ago

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