Why smart grids need smart inverters (and where to find them)



Quick Take:  As rooftop solar continue to proliferate, utilities everywhere are facing the challenge of safely integrating it into the grid. Today's "dumb" inverters are one major challenge. For instance, during a natural disaster, many owners of rooftop solar systems cannot tap into the power they are generating. Their inverters don't have the intelligence to allow them to isolate from the grid.


Smart inverters are here already. What's missing are national standards and testing protocols, writes John Berdner in Renewable Energy World. Ideally, utilities will delegate someone to participate in the standards process that he describes. At a minimum, they should monitor the activities of groups such as the Smart Inverter Working Group (SIWG), IEEE and UL. - By Jesse Berst


The increasing deployment of solar power has created an urgent need to revise the standards governing how they connect and communicate with the grid. In particular, inverters must become smarter.


The Smart Inverter Working Group (SIWG) is at the forefront of these standards revisions. It is working to revise California's rule 21, which governs interconnection. Although applies only to California, it will have a large influence countrywide and even worldwide.


On the national level, ongoing activities are also progressing on amending the UL/ANSI 1741 and IEEE 1547 standards. Before inverters can be certified in the United States, they must be tested by third-party laboratories. But those labs can't move forward without the new standards.


SIWG hopes to develop the first draft test protocols early in 2014 and submit them to UL for review. They could be approved as early as spring 2014. Even so, it will hike a long time for every inverter from every manufacturer to be recertified to the new standards.


To overcome this lag, SWIG is recommending that utilities be allowed to pilot advanced inverters this year. If the field testing goes well, the new inverter standard would then become mandatory in October 2015.


Jesse Berst is the founder and Chief Analyst of SGN and Chairman of the Smart Cities Council, an industry coalition.


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