Soiling

When we clean VectHor photovoltaic systems we observe an interesting pattern: the energy yield of VectHor increases with cleaning, but the change is much less noticeable than with conventional fixed tilt systems. An example is shown in the figure above. While the energy yield of the 30 degree fixed tilt system increases with cleaning by 4%, the VectHor system in the same location and with the same cleaning schedule only increases its energy yield by 1.4%. This is due to a number of factors. Most importantly the soiling of fixed tilt solar panels at tilt angles ranging from 10 to 30 degrees is about 4 times worse than that of vertical solar panels. This is known from the scientific literature. Secondly, while the reflectors accumulate dirt, this dirt is much less detrimental on the reflectors than on the solar panels because dirt drastically reduces optical transmission but has a small effect on hemispherical reflection. As a consequence, while conventional solar systems require frequent cleaning to obtain optimal economic performance, we only recommend our customers one cleaning per year coinciding with yearly inspection and maintenance operations.