The energy conversion efficiency is obviously the most important parameter of any solar cell device.However,a typical solar cell measurement will not give you much information on how to further improve the solar cell efficiency.In this contribution a powerful loss analysis method will be presented that details how various losses in a silicon wafer solar cell can be quantified.It will be shown that,by a combination of high precision measurements,the various loss mechanisms that reduce the short-circuit current,the open-circuit voltage,and the fill factor can be fully quantified.This extensive quantitative analysis,which is not limited to silicon wafer solar cells,provides solar cell researchers and production line engineers a"health check"of their solar cells,which can be used to further improve the efficiency of their solar cells.