What do Fronius codes 475 and 502 insulation fault mean?

Short answer

Fronius codes 447 and 475 (insulation fault between the panels and earth) stop feed-in, while 502 is a warning that insulation on the solar modules is low. They point to damaged cabling, moisture in connectors or a faulty panel. Don't touch the panels or DC cables; Fronius advises contacting your installer to test the system (checked 24 September 2026).