Electric arc-flash energy calculations for photovoltaic systems

Photovoltaic systems have increased in both the quantity of installations and the size of installations over the past decade. As more utility-run systems are being constructed, it is important to consider the safety of operators and maintenance crew during the design and analyses phases. Unfortunately, one potential safety hazard, the electrical arc-flash, is not well understood for photovoltaic systems. The thermal energy released by this hazard can be significant, especially in large photovoltaic systems operating at high voltages and currents. This paper examines the conditions surrounding electric arc-flashes in photovoltaic systems based on typical designs. Using existing models for DC arc-flashes and basic circuit theory, equations and analysis techniques are developed to estimate the thermal energy that can be released if these hazards were to occur. These techniques can be used to determine the hazard-risk-category for the system components most at risk, until more empirical models are developed.