Should rooftop PV mounting layouts keep roof drains and water paths clear?

Yes. Keep building roof drains and rainwater paths unobstructed, and leave safe access for inspection and cleaning. FEMA’s rooftop solar attachment guidance advises against installing panels over roof drains and recommends walkways to each drain. GAF warns that ballasted trays can block drainage and cause ponding, so array layout and rack height should allow roof servicing. Coordinate supports and drainage routes with the roofing manufacturer and project designer before installation. Determine clearances from project-specific requirements and applicable rules, not a generic dimension. This concerns building roof drainage, not the small drain holes in module frames.

Sources: FEMA, Rooftop Solar Panel Attachment: Design, Installation, and Maintenance (April 2018), page 7, For all regions (PDF hosted by Enphase): https://enphase.com/sites/default/files/2021-05/USVI-RA5RooftopSolarPanelAttachment_finalv3_508.pdf GAF, Roof Design Considerations When Incorporating Solar, Solar Array Attachment and Solar Array Layout: https://www.gaf.com/en-us/blog/building-science/roof-design-considerations-when-incorporating-solar-49b20371-7654-49fd-9cf6-244ef3df979d