@solargoat: Official method for testing solar panel cells. Charles Fritts the inventor of the solar cell used this in his laboratory when he invented the solar cell. This practice is still used to day by me. When checking a solar panel to see if it’s working you don’t need fancy electrical equipment, I just repel down the system and touch each individual cell with my hand. If I say a swear word like “gosh darn” or “sheet that’s hot” I get the sn and submit a warranty claim….. Jokes aside I thought hot spots were fixed after we started using diods. Has anyone else seen this problem with newer panels?