The short answer
Usually no. NREL's SAM snow model puts annual energy lost to snow cover at 0% to almost 16% in the continental US; the fall risk is the bigger cost.
Plain explanation
Snow can wipe out a snowy month, but as a share of the whole year NREL's national SAM study found fixed-tilt snow losses from 0% to almost 16% in the continental United States (some Alaska sites up to about 40%). The model assumes snow slides when plane-of-array irradiance and air temperature allow. For most roofs, leave the snow unless you can clear safely from the ground; never walk on modules.
Steps from the source
- Leave snow unless you can clear from the ground
- Check array tilt — steeper often sheds faster
- Never walk on modules; treat roof access as a fall-risk job
"ranges from 0% to 16% in the continental United States (although some sites in Alaska were as high as 40%)"
Word for word from the source.
Source
NREL: Integration, Validation, and Application of a PV Snow Coverage Model in SAM (NREL/TP-6A20-68705), Conclusions: continental US fixed-tilt snow losses 0% to 16%; Alaska up to ~40%; Marion sliding rulewww.osti.gov ↗
Where installers ask this
- Should I remove the snow? (r/solar)
- reddit.com/r/solar/comments/1hdgqhc/snowy_panels_ho_hum_how_to_safely_get_the_snow/
- reddit.com/r/solarenergy/comments/1qqbp5t/do_you_clear_snow_off_your_panels_or_just_let_it/
General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.