context: so If I google how efficient are solar panels and it says the average is roughly 15 to 20% with the max is can get up to is 45%. my question is how is what does that mean?
In: Technology
Not all light that hits a solar panel is used to generate electricity. The Sun emits light on a continuous spectrum, from ultraviolet (UV) to infrared (IR), however the solar panel can only convert a portion of that spectrum into electricity. To be specific, it can only use light with a higher energy than a specific cutoff point which depends on the material the panel is made out of. Light with lower energy is basically ignored, and light with much higher energy is partly converted to electricity and partly lost as heat (so again, not a perfect conversion). You measure the total energy of the sunlight hitting the solar panel (let’s call it A) and the energy output of the panel (let’s call it B), and efficiency is defined as (B/A)%. So a panel which converts a fifth of the energy it receives would have an efficiency of 20%. You can expand the usable sunlight range by basically sandwiching together multiple solar cells which work at different wavelengths of light, these are called “tandem solar cells” and can achieve a higher efficiency, but they get much more expensive and the cost is rarely justified. Instead, you focus on solar panels which perform well in the visible region where most of the total energy is.
Latest Answers