Solar Builder

JAN 2018

Solar Builder focuses on the installation/construction of solar PV systems. We cover the latest PV technology (modules, mounting, inverters, storage, BOS) and equip installers/contractors with tips and tools to make informed purchasing decisions.

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SOLARBUILDERMAG.COM | 17 NEC 2017 changes The 2017 edition of the National Electrical Code (NEC 2017) includes an update to section 690.12 Rapid Shutdown of PV Systems on Buildings. The update pushes the requirement to "module-level" rapid shutdown instead of the "array level" that was listed in NEC 2014. Effective Jan. 1, 2019, this requires conductors inside the array boundary to be discharged to 80 volts or less within 30 seconds of initiating a rapid shutdown event. This requirement comes in addition to the outside the array boundary voltage being limited to 30 volts or less. At first glance, the changes didn't require such a collaborative effort. Module-level electronics could have done the trick and piecemeal proprietary products and one-off collaborations from various manufacturers could have continued as usual. Luckily, that wasn't the case. The SunSpec solution Formed in 2009, the SunSpec Alliance is a trade alliance of more than 100 solar and storage distributed energy industry par- ticipants, together pursuing information standards to enable plug-and-play system interoperability. After nearly two years of intense technical collaboration, the Communication Signal for Rapid Shutdown Interoperability Specification was published in September 2017 as a method to comply with NEC 2017. This spec defines a communication protocol that uses the cabling of the solar array to transmit mes- sages over the DC power lines between the PV modules and a master control device located near the inverter. In addition, PV module manufacturers can implement the protocol on intelligent devices embedded in the junction box of each PV module. A master control device associated with the inverter communicates with the PV modules. Altogether, the specification enables plug-and-play interoperability and any-to- any rapid shutdown solutions. "This open standard delivers multiple benefits to the distrib- uted energy industry, most notably lower integration costs and the freedom to choose from an array of interoperable products," saysTom Tansy, chairman of the SunSpec Alliance. What's this mean for me right now? 1. If you are a big fan of installing microinverters, you're already meeting these rapid shutdown requirements. 2. As mentioned earlier, the implementation date for NEC 2017 is Jan. 1, 2019. Depending on the Authority Having Jurisdiction where you do business, you may not even be held to the NEC 2014 requirement right now, let alone NEC 2017 when it arrives. The Northeast portion of the country will be the earli- est adopters, followed by California. 3. If you are going to be held to NEC 2017 — or just generally would like to comply on your own — sit back and wait for these SunSpec-certified products to hit the market and design systems the way you always have.

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