Despite the high cost and relative immaturity of concentrated solarpower (CSP), South Africa is emerging as one of the global focusareas for this technology because the country has one of the bestsolar resources on the planet suited to it.

For CSP (as well as concentratedphotovoltaics (CPV)) the key parameter is direct normal irradiance (DNI). This is in comparisonwith global horizontal irradiance (GNI)which is more relevant for conventionalphotovoltaics. While the vast tractsof northern and Saharan Africa haveoutstanding GNI, that region’s overallfigures for DNI are less impressive.

Though some locales such as parts ofMorocco do have excellent DNI, much ofthat overall region has challenges of dustand attenuation.

In general, high elevation areas havehigher DNI due to less absorption andscattering of sunlight. Rainfall and cloudcover affect DNI, so arid or semi-aridareas with clear skies are best. The bestDNI typically lies at latitudes from 10O to40O North or South. Closer to the equatorthe atmosphere is usually too cloudy andwet in summer, and at higher latitudesthe weather is usually too cloudy.

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