Designing Buildings for Solar Power and Fire Safety

Chuck Colgan's picture

Tools for architects and designers to create safer solar installations

With the rapidly growing demand nationwide for solar systems to supply electricity for new commercial, industrial and multitenant buildings, architects and building designers need to know how to plan installations that are not only functionally correct and aesthetically fitting, but also account for concerns about safety during firefighting.

Solar photovoltaic (PV) panels and related support systems present unique challenges for anyone working on a rooftop, but are especially an issue for first responders applying normal tactics for fire suppression, building ventilation and electrical shock prevention – always in emergencies and oftentimes at night.

The Building Codes Assistance Project (BCAP) and Center for Sustainable Energy are offering a series of day-long workshops at cities coast-to-coast specifically for architects and designers to better understand how to plan and construct solar PV systems. Sponsored by the Department of Energy’s SunShot Initiative, the workshops cover solar integration into building design, utility connections, codes and other aspects of solar, and highlight fire safety issues.

Upcoming trainings are scheduled in Albuquerque, New Mexico; Dallas, Texas; Raleigh, North Carolina; Columbus, Ohio; and other locations. For information and registration, visit BCAP’s Solar Training and Education for Professionals website.

Solar codes and standards

As firefighters respond to a burning building with solar PV, they need to feel confident that the systems they face conform with safety requirements and are installed to meet specific codes and standards set by local and state building departments. While it is exceedingly rare for PV installations to start a fire, their physical placement, wiring and shutdown procedures have specific fire and electrical code requirements that need to be considered during initial system design.

Most PV panels have glass surfaces and generally don’t catch fire, but several first responder concerns need to be addressed during the system design to mitigate the potential impact on firefighting operations. These concerns include access impediment, tripping hazards and firefighter vulnerability to electrical and casualty hazards during rooftop firefighting operations.

The International Code Council and National Fire Protection Association have helped lead efforts addressing standardization of firefighting safety guidelines. From their work and contributions from other organizations, most state and city building codes now call for solar installations that facilitate fire suppression operations and ensure firefighter safety by including provisions for panel positioning, placement of wires and supporting equipment.

PV system fire classification

State and local building codes require that rooftop mounted photovoltaic panel systems must be tested, listed and identified with a fire classification that is based on the type of construction of the building and the required fire classification for the roof covering.

Placement, access and ventilation

PV code design requirements begin by giving fire personnel adequate access to the roof and take into account the locations of HVAC equipment, electrical connections, access hatches, skylights and other roof-mounted features. To ensure safety, a 6-foot wide clearance is required around the roof edges, and typically, a minimum 4-foot cleared space around standpipes, ventilation and roof access hatches and other areas. When planning clearances, consideration should be given to wiring conduits and cable trays that may require extra space or ramps and step-overs for wiring.

Pathways are the next level of concern, creating multiple avenues for firefighters to safely and effectively move about the roof, inspect areas and, when needed, vent smoke from within the building. Fire codes call for centerline axis and straight-line pathways from the perimeter access to skylights, ventilation hatches and PV system components that are at least 4 feet wide. To further facilitate smoke ventilation opportunities, the size of PV array sections is limited to not greater than 150 x 150 feet in either axis.

It’s critical that pathways are structurally capable of supporting all elements of the “live load” associated with fire crews and their equipment in addition to water sprayed to fight the fire or even weather conditions, such as snow and ice.

Shutting down shock hazards    

Because PV systems collect sunlight and convert it to direct current (DC), just disconnecting standard alternating current (AC) feed-in lines won’t stop the flow of power. To avoid life-threatening electric shock hazards, the National Electrical Code requires PV systems to have a dedicated rapid shutdown switch installed outside of the building near the DC-to-AC inverter that may be triggered manually or automatically when the AC supply is shut off. However, the solar DC supply may still be live from the panels to the central inverter and other system components.

Approaches to decreasing shock hazard include installing DC-DC power optimizers along with an inverter that can shut down rapidly or using microinverters on each solar panel or fitted on a section of panels that replace a central inverter. When the building’s AC circuit goes down for any reason, each unit in a microinverter array performs its own shutdown function. Using microinverters also increases overall electrical safety as they use AC to distribute power from the panels to the rest of the system.

Check with the experts

Building design professionals need to understand all the safety issues surrounding solar system installations and assure that firefighting precautions are correctly incorporated when adding solar panels to their construction planning. The best advice is to contact local building departments early in the project design so that you know which national codes they enforce and any special local design and safety requirements.

National Workshops
Audience: Architects & Building Designers
Topics: Solar integration into building design, utility connections, codes and other aspects of solar
Dates & Registration

Chuck Colgan