10.2 Practical notes when integrating solar into a new build

1. Meters: confirm the city's expectations on the ADU's electrical panel and meter layout. If the ADU has a separate meter, the ADU's solar cannot share electricity with the main house. If they share the main meter, a single solar system can serve both. Lock this in during design — discovering you need to rework after the install is finished is painful.

1. Roof reservation: get the solar layout decided as early as possible, ideally at the ADU's roof design stage. Panels need fire-access setbacks, so for new builds try to design large continuous roof sections instead of many small fragments. Roofs that look spacious can shrink to near-zero after setback math eats them up. Especially if you want solar to power the entire house, the roof layout, orientation, and per-section length and width directly determine the maximum system capacity.

1. During construction: pre-route the solar wiring during the build. It will save money and look much cleaner. Many homeowners wait until the home is nearly done before thinking about solar — at which point conduit that could have been buried inside the walls has to be surface-mounted, drilling holes all over the exterior. Two runs are good candidates for in-wall routing:

• From the roof down to the ground floor.
• From the inverter to the main panel.

Both must be installed before drywall is hung, so the solar contractor needs to make a pre-drywall visit.

Also: even if today's system is small, future expansion is likely. Have the contractor pre-pull extra conduit, or split a single planned run into two parallel runs into the inverter. When expansion happens later, you won't need to re-pull conduit — the install will be cleaner and dramatically cheaper.

1. Watch where roof vents go on a new build

Builders rarely think about future solar when planning the roof, so vent placement is often arbitrary — and that arbitrarily eats up panel real estate. Hand the builder your solar design as early as possible and ask them to leave space for the panels. They can usually shift vents to land between panels, which doesn't disrupt the overall layout much. But if a vent sits dead-center on a future panel position, there is no fix — you simply lose that panel. With multiple vents per roof section, this can dramatically reduce capacity. Coordinate early.