Humidity: A factor in the appropriate positioning of a photovoltaic power station

Abstract

Humidity is an ambient parameter which refracts, reflects and diffracts the direct visible solar radiation. This dispersion effect results in deterring the reception of the direct component of solar radiation by water vapour particles present in the atmosphere. Tropical Sudan Savannah region is known to be a hot climatic area with a highly humidified atmosphere. This paper investigates the effect of humidity on the reception of solar radiation and the resulting effect on the generated electrical power in this climatic region. A monocrystalline silicon photovoltaic module containing 33 cells connected in series was used for the investigation. The module open-circuit voltage (V OC) and short-circuit current (I SC) variations with irradiance level have been established. The variation of solar radiation intensity with humidity has also been analysed. Result indicates a little variation of the V OC with irradiance. On the other hand, the I SC has been observed to vary largely with the irradiance level. Also, the analysis of the variation of humidity with irradiance level reveals a non-linear relationship. This shows the dependence of photovoltaic module efficiency not only on the type of cell structure but also on the maximum irradiance and consequently the humidity of the surrounding.