Evaluation of solar modelling techniques through experiment on a 627 kWp photo-voltaic solar power plant at Edinburgh College—Midlothian Campus, Scotland

The accuracy and applicability of existing methods of solar resource modelling and solar photovoltaic module performance are investigated in the case of a ground array installation at Edinburgh College, Midlothian Campus, the principal derived quantities consisting of slope irradiation, cell temperature, and cell efficiency. Experimental data were obtained on site through both automated and manual measurements for comparison with the calculated quantities. Results indicate that the horizontal-to-slope conversion models used are extremely accurate, with greater than 99% degree of confidence in the calculated results. Likewise, correlations between measured and calculated cell temperature were very high at up to 94%. Estimations of the cell efficiency and hence module output were less reliable, however, with only one of the models used, for one of the days studied, giving reasonable results. Efficiency values were, however, in the approximately correct range of 15%–20%.