How big is a solar panel? Post author:freedomtask2 Post published:January 15, 2020 Post category:FAQ The average size of most panels for rooftop solar installation is about 65″(5.4 ft) by 39″(3.25ft) You Might Also Like What if I am thinking of moving? January 14, 2020 what is a critter guard? January 13, 2020 What is the difference between grid-tied and off-grid solar systems? January 15, 2020