City of Tucson - Solar Readiness and EV-Ready Sustainability Codes

Solar Readiness

Tucson adopted an ordinance in June 2008 that requires all new single-family homes and duplexes in Tucson to be "solar-ready." 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.

Electric Vehicle Readiness

Residential

Tuscon adopted an ordinance in June 2021 that requires all new one-to-two family dwellings and townhouses with on-site parking spaces to provide at least 1 EV Ready space. "EV Ready" is defined as a designated parking space with one 40-ampere minimum 208-volt or 240-volt dedicated single phase branch circuit for electric vehicle supply equipment (EVSE). The circuit must terminate in a suitable termination point (such as a NEMA 14-50R receptacle or an EVSE) and be located within 10 feet of the proposed parking space.

Construction documents must indicate the EVSE location and provide information on wiring methods, circuiting, and electrical load calculations that demonstrate the premise's electrical system can accommodate the EV charging load.

Multifamily Residential and Commercial

The city adopted a second ordinance in August 2022 for EV-readiness in multi-family residential and commercial buildings. The percentage of spaces that must have EVSE installed, must be EV Ready, and must be EV Capable varies from 5% to 20% for each, depending on the type of building. At least 4% of EVSE spaces (or at least 1 space, if less than 25 spaces) must be accessible EV charging spaces.

Installed EVSE can be networked or non-networked Level 2 chargers, and must be within 6 feet of a designated parking space. A single Level 3 charger counts as 3 EVSE spaces. "EV Ready" has the same meaning as under the residential requirements, but with a 6-foot limit. "EV Capable" is defined as a parking space within 6 feet of the termination of a listed electrical conduit to accommodate a future individual branch circuit originating at the main service or subpanel. The panel should provide capacity to accommodate a 40-ampere minimum 208-volt or 240-volt dedicated branch circuit. The conduit should be installed so that minimal removal of materials is necessary to complete a future installation.

The codes allow the number of required motor vehicle parking spaces to be reduced if the parking lot exceeds the minimum number of required EVSE spaces, up to 30%; the number of required EVSE spaces is based on the original number of required parking spaces. Total parking spaces can be reduced by 1 or 2 for each EVSE installed, depending on the type of building. Total parking spaces can be reduced by 1 for each EV Ready space, depending on the type of building.