Solar in Portland, Maine, starts with a roof that has to survive a nor'easter off Casco Bay before it carries anything else. Wind on Munjoy Hill and the proms lifts shingles and drives rain uphill. Salt works on hardware. A West End roof in brick may be older, steeper, and partly shaded by the block. A lower roof toward the cove ponds. If the deck is soft or the flashing already failed in the last storm, fix that before a mount gives water a new door. Say the neighborhood and the slope.
Shade from close peninsula houses and from street trees can cut the day short. That is siting, not a forecast of output, and a phone call should not invent one. Snow here is often wet and then it freezes, and a smooth surface will shed it onto a tight walk or a lower roof. Attachments have to live with uplift in an onshore gale. Flat roofs and pitched asphalt are different layouts. A roof deck people use cannot become equipment without a plan for walking and for the membrane.
Electrical panels in these older houses are often full and in damp cellars. Access is a narrow lot on a windy street, with no generous driveway, during the same season everyone else is trying to dry out from the last blow. Ask about structure and about flashing that will see rain driven up under the edge, not a calm summer hour. Slate or a decorative metal roof is not a casual place to drill. Mention it if that is what you have.
Shade you will not cut and a roof at the end of its life belong in the first conversation. So does the simple fact that the next nor'easter will test every new hole. Ask how each attachment is closed against that weather and how a later leak gets repaired without pulling the field apart. A shared roof or a multi-family building needs an honest answer about who controls the surface.
Call with the exposure, the material, and what shades the roof. Mention salt air, a deck, a soft spot, or a prom-facing slope. Ask how it stays on in a gale. Do not expect a production promise. Call the number on this page.