Do Solar Panels Add to Roof Snow Load?

Rooftop solar is booming in snowy states, and a common question is whether the panels add to the roof's snow load. The honest answer: panels mostly add dead load, but they also change how snow behaves on the roof.

Dead load first

A typical rooftop array adds roughly 3–4 psf of dead load (panels plus racking). That is separate from snow load but stacks on top of it in the load combinations, so the structure must carry both.

Panels change snow behaviour

Smooth panel glass is slippery and can shed snow faster than the surrounding roof, but the racking can also trap snow at the lower edge and create mini-drifts between rows. In heavy-snow regions, designers sometimes treat the array area carefully rather than assuming it sheds clean.

What to check

Confirm the roof's existing snow load capacity, add the array dead load, and make sure the attachment points and rafters still work. Run your design roof snow load here first so you know the number the structure already has to meet.