Applying measured reflection from the ground to simulations of thermal perfromance of solar collectors

Solar radiation on tilted and vertical surfaces in the Arctic is, in large parts of the year, strongly influenced by reflection from snow. In connection with planning and optimization of energy efficient buildings and solar energy systems in the Arctic, it is important to have an accurate representation of the reflection from the ground. In this study a more accurate description of the albedo is obtained based on detailed measurements from a solar hat, installed at ASIAQ’s climate station in Sisimiut, Greenland. The solar hat measures the global radiation on horizontal, the total radiation on vertical surfaces facing north, south, east and west, and radiation reflected from the ground on vertical surfaces facing north, south, east and west. Based on measured data from 2004-2007 the albedo is determined for each month of the year as a function of the difference between the solar azimuth and the azimuth of the surface in question. The paper will present an analysis of simulations of the thermal performance of solar collectors using the standard description of the albedo and using the albedo determined by the measurements. It will be elucidated how important an accurate description of the reflection from the ground is for the thermal performance of solar collectors.