More Ohioans are investing in photovoltaic (PV) solar systems to power their homes, businesses, and agricultural operations than ever before. Photovoltaic solar projects certified by the Public Utilities Commission of Ohio (PUCO) increased from 14 in 2009 to 1,834 in January of 2016. Significant cost reductions, favorable energy policy, and the ‘green’ appeal of PV solar systems help explain the growth in popularity, but the growing popularity is also a cause for concern.

The growth of PV solar systems installed on residential and commercial buildings presents new safety hazards to system owners and emergency first responders. When exposed to light, a grid-tied PV solar system will generate direct current (DC) electricity that travels through wires and combiner boxes to an inverter that converts the energy to alternating current (AC) electricity. The inability to power-down PV solar panels exposed to sunlight creates potential concerns for emergency first responders looking to extinguish a fire. Simply put, when exposed to light, the panels will generate electricity energizing the system’s DC wiring, causing first responders to proceed as if the building is energized.

In response to this safety concern, the 2014 National Electric Code (NEC) developed rapid shutdown standards for PV solar systems on buildings (NEC 2014, Section 690.12). In general terms, the Section 690.12 Rapid Shutdown of PV Systems on Buildings requires that energized conductors (AC or DC) can be de-energized on demand, limiting the energized portion of the conductors to not extend more that 10 feet from the PV array or more than 5 feet within a building. Ohio adopted the 2014 NEC for commercial applications effective January 1, 2015 and residential applications effective February 8, 2016.

To learn more, read the fact sheet posted here.

(Submitted by Eric Romich, Assistant Professor and Extension Field Specialist, Energy Development)