Most new panels announced these days top 20% efficiency[1]. Output is guaranteed to 90% after 10 years, 80% after 20, real world often better[2]. [1] https://

Most new panels announced these days top 20% efficiency[1]. Output is guaranteed to 90% after 10 years, 80% after 20, real world often better[2]. [1] https://www.greentechmedia.com/articles/read/Is-SolarCitys-New-PV-Module-the-Worlds-Most-Efficient-Rooftop-Solar-Pane https://www.greentechmedia.com/articles/read/Is-SolarCitys-N... [2] http://sroeco.com/solar/solar-efficiency-losses-over-time/ http://sroeco.com/solar/solar-efficiency-losses-over-time/