Climatological investigation for solar-power stations in the Swiss Alps

An extended measuring campaign has been performed to obtain all the relevant climatological data at a representative power plant located in the Swiss Alps, as a basis for studying the technical and economic feasibility of solar power stations in Switzerland. The data include the irradiations: direct normal, global normal, global horizontal, diffuse horizontal and global inclined at 30, 45 and 60° to the South. From the results, it is concluded that suntracking photovoltaic panels would receive 1.7 times more energy per square metre per year than solar thermal systems converting the direct normal irradiation only. Unexpectedly high global irradiation values in southwards-directed, 60° inclined planes confirmed the enhancing effect of snow reflection, leading to a valuable extra output of panels in winter. Snow and cloud-side reflection occasionally caused peak values of the global normal irradiation, far exceeding the solar constant of 1367 W/m2 (up to 2000 W/m2). The irradiation data are supplemented by wind, rainfall, ambient temperature and humidity measurements. Some solar spectra were also acquired at the end of the project. They contribute to the correct selection of the panel type. Highly resolved measurements of the direct normal irradiation were used to perform simulations of the volumetric receiver of a solar thermal power station.