Preliminary study of environmental solid particles on solar flat surfaces in the UK

The increased use of flat solar devices, such as photovoltaic (PV) panels and solar water heaters (SWH) globally has prompted this area of research to identify the efficiency reduction due to deposited solid particles on their surfaces which reduces the absorbed solar radiation on which the device depends for generating electricity or heat. Most manufacturers of these devices quote their efficiency as measured in a clean environment, and normally at 20̊C and one air mass. Efficiency reduction due dirty surfaces can be as high as 60% if the installation is in dusty or polluted climate and not cleaned regularly. In this preliminary research, the authors are studying the UK conditions on flat surfaces when they are not cleaned, over one, two, three and four week periods. Additionally, the study will investigate the various angles of tilt to the horizontal in the natural environment to achieve the maximum incident solar radiation on them. Because UK, environment has many rainy days, the results showed a small reduction in solar absorption from flat surfaces devices placed in the sun in an open environment. This is equal to 5% transmittance reduction after a period of three weeks though the glass samples exposed to the environment. Outdoor particle and dust distribution lies in the range of smaller than 400 microns with the most frequency smaller than 20 microns. Moreover, indoor laboratory experiments have been carried out to show quantitatively the effect of dust/pollution on the glass surfaces. Finally, a comparison between the results from outdoor and indoor experiments has been provided.