The continued drive to lower the cost of large photovoltaic (PV) systems has designers, developers and engineering procurement companies looking beyond 600- and 1000-volt systems to 1500 volt. Increased system voltage allows for longer strings, which cuts back the number of combiners and wiring in the DC collection system, reducing labor costs. By decreasing wire losses and increasing efficiency at the inverter, higher voltage systems also improve financial returns and lessen the levelized cost of energy, especially across large commercial and utility-scale systems.

The use of higher voltages in PV modules has been limited by electrical codes, standards and the availability of products. While the NEC limits residential systems serving one or two families to 600 volts, this is not the case for commercial rooftop and ground-mounted systems. Higher voltage installations are addressed for these uses within the 2014 NEC, “other installations with maximum system voltage over 1000 volts shall comply with Article 690, Part IX.”

In response to the growing need of the PV industry for higher-voltage photovoltaic systems, UL has also recently published requirements for the evaluation and certification of 1500V PV modules. The requirements examine the construction of the PV module, junction box, cables and connectors as per the standard UL1703 and addresses potential electrical hazards associated with the increased voltage.

As a result, getting approval to design and deploy 1500-volt systems is now easier, enabling the pursuit of new opportunities.

For further information on PV standards or UL’s solar energy services, please stop by SPI, Booth #2942 or contact Scott.Jezwinski@ul.com.