City of Tucson - Solar Design Requirement for Homes

Tucson adopted an ordinance in June 2008 that requires all new single-family homes and duplexes in Tucson to be "solar-ready." The ordinance was developed by a stakeholder group which included Technicians for Sustainability, the Tucson Association of Realtors, the Sierra Club, the Southern Arizona Homebuilders Association, architectural professionals, solar energy companies and elements of the city government. The ordinance requires all new homes either to have a photovoltaic (PV) and solar water heating system installed, or to have all the necessary hardware installed so that a system can easily be installed at a later date.

To comply with this requirement, new homes must either have a complete solar water heating system installed or comply with one of two solar stub-out options. Option one requires the installation of two insulated pipes and a suitably sized conduit (for two pairs of monitoring and control wires) that run from the water heater area through the roof and are capped. Option two does not require the installation of pipes, but it does require the installation of a sleeve or conduit of sufficient size to hold the two insulated pipes and wires. To comply with option two there must be a straight line from the water heater area to the roof. Both options will greatly cut down on the cost of installing a system at a later date.

To comply with the PV requirement, a site plan must indicate the best roof space for locating the PV panels, and provide a roof structure designed for the additional collector weight. The site plan must also illustrate the best space available for accommodating PV equipment (meter, inverter, disconnect), and it should be adjacent to the electrical service panel or on a wall near the proposed location of the panels. There must also be a minimum 3,800-volt-ampere PV electrical load entry on the Service Load Calculation, and an Electrical Panel Schedule with a 240-volt circuit breaker space labeled “reserved for Photovoltaic.”

These requirements may be waived if it can be demonstrated to the building official that compliance is not practical due to shading, building orientation, construction constraints, or the configuration of the parcel of land.