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Solar Energy 101

Solar Power 101

Solar Energy, like all other renewable energies, is very safe and environmentally friendly. There are no emissions as the source of fuel is the sun, unlike coal-powered stations. Solar offers a limitless supply of clean, safe, renewable energy for heat or power. And it's more affordable, more efficient, and more reliable than ever.

Most areas in South Africa average more than 2 500 hours of sunshine per year, and average solar-radiation levels range between 4.5 and 6.5kWh/m2 in one day. The southern African region, and in fact the whole of Africa, has sunshine all year round. The annual 24-hour global solar radiation average is about 220 W/m2 for South Africa, compared with about 150 W/m2 for parts of the USA, and about 100 W/m2 for Europe and the United Kingdom. This makes South Africa's local resource one of the highest in the world.

The use of solar energy is the most readily accessible resource in South Africa. It lends itself to a number of potential uses and the country's solar-equipment industry is developing.

Water Heating

Solar hot water systems use energy from the sun to heat water. In the Southern Hemisphere 60-70% of the domestic hot water usage of temperatures rising up to 90oc can be provided by solar heating systems. The most common types of solar water heaters are evacuated tube collectors and glazed flat plate collectors generally are used for domestic hot water; and unglazed plastic collectors are used mainly to heat swimming pools.

As of 2007, the total installed capacity of solar hot water systems is approximately 154 GW. China is the world leader in their deployment with 70 GW installed as of 2006 and a long-term goal of 210 GW by 2020. See Solar geysers

Heating, Ventilation and Air Cooling (HVAC)

Thermal mass is any material that can be used to store heat — heat from the Sun in the case of solar energy. Common thermal mass materials include stone, cement and water. Historically they have been used in arid climates or warm temperate regions to keep buildings cool by absorbing solar energy during the day and radiating stored heat to the cooler atmosphere at night. However they can be used in cold temperate areas to maintain warmth as well. The size and placement of thermal mass depend on several factors such as climate, daylighting and shading conditions. When properly incorporated, thermal mass maintains space temperatures in a comfortable range and reduces the need for auxiliary heating and cooling equipment. See Passive solar building design.