St. Louis recently passed a new law requiring all new buildings to be made solar-ready.
All new structures—commercial and residential—must reserve rooftop sections for solar panels to be easily installed. The ordinance does not mandate that rooftop solar be installed.
The solar-ready zone must be at least 40% of the roof area. It can be one contiguous area or multiple smaller sub-zone areas that are no less than five feet in width at their narrowest point. The solar-ready area cannot be obstructed by pipes, vents, HVAC equipment, or other shadow-casting elements.
Construction documents must outline pathways for routing of piping from the solar-ready zone to the building’s electrical service panel or service hot water system. The electrical panel must also have reserved space for a dual-pole circuit breaker to support future solar installations.
New buildings that have permanently-installed onsite generation systems already, buildings whose solar-ready zones would be shaded from sunlight for more than 70% of the day, and buildings where a licensed design professional has deemed that the solar radiation available to the building is not suitable to a solar-ready zone or because the area requirement cannot be met due to extensive rooftop obstructions, may be exempt.