For the first time since 1984 energy generated by renewable sources outweighed nuclear generation in March and April of this year.
Although strong springtime solar and wind production coupled with scheduled maintenance at nuclear plants resulted in the inflection of generation, this pattern more broadly reflects the reality that renewables will continue to increase their share of the U.S. energy generation mix. Paramount to the evolution from centralized thermal generators to distributed and intermittent energy sources is grid reliability. With this in mind, Underwriters Laboratories (UL) and the California Public Utilities Commission (CPUC) issued testing standards for PV and grid interactive solar electric inverters (and other power conversion equipment).
UL 1741 SA Advanced Inverter Testing
UL 1741 SA is a product safety standard that lays out the manufacturing (including software) and product testing requirements with the goal of producing inverters more capable of riding through grid excursions or even actively managing grid reliability functions.
Up to this point traditional utility interconnection requirements have dictated that PV systems (read inverters) disconnect from the grid during departures from normal grid conditions. As solar penetration increases across the country, it may no longer be desirable for a PV system to disconnect from the grid entirely as this could exacerbate grid instability.