Even small objects, such as dust and leaves, can block sunlight from reaching solar cells, and understanding how the loss of incoming radiation affects power output is essential for optimizing photovoltaic technology. In the Journal of Renewable and Sustainable Energy, researchers explore how different shade conditions impact performance of single solar cells and two-cell systems connected in series and parallel. They found that the decrease in output current of a single cell or two cells connected in parallel was nearly identical to the ratio of shade to sunlight. However, for two cells running in series, there was excess power loss.