Solar in Detroit starts with an older roof and a tight lot, not a picture from the sky. Freeze and thaw work on every mount. Snow slides off some slopes and sits on low porch roofs that should not carry an array. Street trees and the next house shade more of the day than an open lot would. If the covering is tired, the deck comes before the modules.
Do not accept a layout drawn only from above. It will miss a soft valley, chimney mortar that has let go of the flashing, and a basement electrical service never meant for more load. Ask who stands behind a leak at each penetration, and how the array comes off when this old roof is replaced. Narrow side yards and alley gates decide whether materials can even reach the slope.
Modules and inverters should be named as specific gear, not a family of products. String equipment and module-level electronics behave differently when a chimney shade or the house next door covers one corner. You should know who gets the call when an inverter goes quiet under a gray winter sky. A garage behind the house may have the clearer sky and the weaker deck. Say if the gear should belong to you.
Permits and the utility permission to operate are part of the work. Ask who files them, and what changes if the layout has to move off a bad section of deck. Winter output on a Detroit roof will not resemble a bright June afternoon, between snow, low sun, and lake cloud. That belongs in the conversation before the array is up. Ice leaving a valley can also beat on anything mounted in its path.
Say the age of the roof, which way the main slope faces, and whether a tree owns the southern sky. Mention soft chimney flashing if you already know about it. Call the number on this page.