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 equivalent of a large coal-fired power station(2 000MW+) is used to provide hot water on tap to the domestic sector alone. Since the inception of the accelerated domestic electrification programme through grid extension, a major distortion of the national load curve has emerged, with the early evening load peak growing significantly.
Modelling indicates that the introduction of solar water-heating can ameliorate the situation substantially. Switching from electrical to solar water-heating can, therefore, have significant economic and environmental benefits.
There are economic benefits for home owners in reducing their energy bills. Expensive generation capacity to address load peaks will be obviated, and the introduction of new base-load capacity will be postponed. Benefits for the country include reducing greenhouse gas (GHG) emissions, and the release of scarce capital for other pressing needs.
Solar water heaters have many benefits both for the customer and for South Africa. The customer benefits by having a reduced electricity bill and the country benefits because less power has to be generated by Eskom and so less pollution is generated.