Photovoltaic panels are more sensitive to the angle and intensity of light striking them than solar hot water panels are, but the most serious impact to PV performance is partial shading. Solar cells on a panel are strung together in series, like links in a chain. If a shadow falls on one cell, or link, the chain is broken and output of the entire panel is seriously degraded.

Even thin lines of shadow can interrupt PV generation. These images show the impact of adjusting an adjacent row of PV panels so they do not cast a shadow along the bottom of the first row.