Overcurrent Protection Designed for PV

Direct-current (DC) electrical distribution is certainly nothing new – 
in fact, the technology was the basis for Thomas Edison’s original 
designs back in the 1880s. While alternating current (AC) distribution 
has since become more prevalent, the rapid growth in solar photovoltaic 
(PV) installations and more recent interest in energy storage has 
electrical contractors paying attention to DC requirements all over 
again. Mersen

Chuck Ross

Direct-current (DC) electrical distribution is certainly nothing new – in fact, the technology was the basis for Thomas Edison’s original designs back in the 1880s. While alternating current (AC) distribution has since become more prevalent, the rapid growth in solar photovoltaic (PV) installations and more recent interest in energy storage has electrical contractors paying attention to DC requirements all over again.

Illustrating just how important these two resources have become, solar, at all sizes, was the top source of new U.S. generating capacity in 2016, according to the U.S. Solar Energy Industries Association. And the energy storage market grew by 100% last year, versus 2015, in added capacity. In both cases, this growth was driven by larger, utility-scale projects, but interest in distributed commercial-scale – and even residential – installations also is growing, in both cases.

Growing alongside PV and energy-storage systems of all sizes is interest in related overcurrent protection devices. For PV installations, especially, these products need to address the reality that a short circuit current might not be much higher than a normal current. As a result, a typical alternating current (AC) circuit breaker might not operate quickly enough in an overcurrent situation.

To address DC applications in which devices might be subject to both high- and low-overcurrent situations, manufacturers have begun to market a new generation of DC protection products capable of addressing both scenarios. Unlike fuses, these hybrid offerings bring together two different technologies to address the range of overcurrent issues that might be faced in PV and battery-based energy-storage applications.

In some cases, these devices combine a semiconductor and a switch, which allows resettable and arc-less operation. Other designs for higher-voltage uses bring together a fast-acting pyro element controlled by a gate current, along with a parallel clearing element. Both options offer system designers new choices to meet application-specific demands as DC overcurrent protection becomes a more important topic of discussion.


Photo courtesy of Mersen

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