Solar in Oregon has to answer whether the roof can carry the array. Fir trees erase a south slope that looked clear in a drawing. East of the Cascades the sun is stronger and the wind is the harder question for the mounts. The visit is the covering, the framing, and the electrical service.
Do not attach rails to a composition roof that is mossed through, soft, or already leaking at the valleys. Ask how the feet are flashed against months of rain and what happens when the roof is replaced later. A photo from the air has not stood on a slick deck or looked at older rafters in a bungalow. Someone has to see whether the framing can carry the array. Say what service is already in the panel.
Name the modules and the inverter. Ask who owns the panels and who gets called when an inverter goes quiet. Put that equipment where you can reach it in the wet season, not in a crawl you avoid or behind a locked gate. Shade from a fir or a neighbor roof can wipe out the hours a drawing assumed. A bare east-side lot is not a shaded valley roof, and the rails are not obvious until you say which one you have.
Wind on the dry side and wet penetrations on the west side are hardware questions about mounts, glass, and flashing. They are not a script about clear afternoons. If a roof repair or a claim is open, finish the covering first so the feet are not an obstacle on a rotten deck. Attachments that block a valley already packed with needles are a bad trade. You want framing that can carry the load and a name for the quiet-inverter call.
Say the town, whether the roof is mossed or tired, and whether shade or wind is the real limit. Mention who owns the panels if they are already up, and who you call when the inverter is quiet. If the covering is soft, start there. The array waits on the roof, not the other way around. Call the number on this page.