Use the formula Efficiency = (Output Power / Input Power) × 100% to find out how well your solar panel changes sunlight into electricity. Solar panels can make energy even when it is cloudy or cold, so do not think they only work when it is sunny. Efficiency, in combination with latitude and weather, determine the energy output of a solar system. For example, a solar panel with 20% efficiency and an area of 1 m 2 produces 200 kWh/yr. The conversion efficiency of a photovoltaic (PV) cell, or solar cell, is the percentage of the solar energy shining on a PV device that is converted into usable electricity. Improving this conversion efficiency is a key goal of research and helps make PV technologies cost-competitive with. Solar panels, also known as solar modules, are an assembly of individual photovoltaic cells that are electrically interconnected together in series and/or parallel combinations to produce an array with a specific power output. Learn how NLR can help your team with certified efficiency measurements.