Solar Panels Efficiency
When efficiency of solar cells or solar panels are talked about, always keep in mind that this has something to do with size. All solar cells/panels almost always come with an efficiency rating. To understand this right away, just compare a 200Wp high efficiency vs 200Wp low efficiency solar panel. They both produce the same potential amount of electricity which is 200Wp. The only difference is that the high efficiency panel is smaller in size than the low efficiency panel. If you have enough roof space or ground, it does not matter whether you use high or low efficiency panels as long as you reach your required output power.