Solar in Boston starts on a roof that may already be working as a deck, a dryer vent run, and a place for the neighbor's shade. Triple-deckers stand close enough that the south wall of one house is the view from the next kitchen. A slope that looks sunny at noon can be in shade by midafternoon because of a taller block on the corner. Flat roofs take a different mount from pitched asphalt in Hyde Park or West Roxbury. Say which roof you have.
The deck has to be sound before anyone fastens equipment to it. A spongy low-slope roof in Dorchester, a ponding seam, or a membrane patched in several eras is a reason to fix the roof first. Party walls, chimneys, and skylights break up the open area. Hardware has to live with harbor wind in East Boston and South Boston and with ice that slides off a pitched roof onto a lower porch. None of this is a promise about how much the array will do in a year.
Brick rows on Beacon Hill, the Back Bay, and the South End bring visibility and structure questions that a frame house on a side street does not. Drilling a decorative slate or a copper roof is a serious alteration, not a Saturday task. Access without a driveway means materials come through a narrow hall or up from the street. The electrical panel in an old three-family may already be full, split by floor, or located in a basement that floods. Say what you know about the service.
A roof deck that people use cannot become an array without a plan for walking, vents, and the membrane seams. Shade from a tree the block likes, or from a new story next door, belongs in the conversation before equipment is ordered. Ask how the attachments will be flashed so the next nor'easter does not enter through the mounts.
Call with the neighborhood, flat or pitched, and what shades the roof. Mention a deck, slate, copper, or a tired rubber roof if that is what you are standing under. Ask about structure and flashing, and how a later leak at a mount would be closed. Call the number on this page.