All, If the grid-tie inverter is operating under UL1741 (and therefore IEEE1547), then the inverter has to cease output within 1 second of the voltage going over 10% of the base voltage. So in the case where the generator is outputting and the load is less than the inverter output, the voltage will rise and the inverter will cease to ouput. The voltage will then drop, the inverter will reconnect, and the cycle will repeat itself. That assumes the generator's waveform is clean enough for the inverter to connect to in the first place. James Worden from Solectria Renewables covered this briefly in a SolarPro article: http://solarprofessional.com/article/?file=SP2_5_pg16_QandA_2.
- Mike -- Michael Kelly Project Manager / Project Engineer NABCEP Certified Solar PV Installer ™ SolarFlair Energy, Inc. 11 Mayhew Street Framingham, MA 01702 Direct Mobile: 617-899-9840 Main Phone: 508-293-4293 Main Fax: 508-293-4003 m...@solarflair.com On Tue, Mar 2, 2010 at 9:29 AM, Drake Chamberlin < drake.chamber...@redwoodalliance.org> wrote: > I was recently told by SMA that in the event that the inverters did connect > to generator output, and the load was less than the inverter output, that > the voltage would rise and the inverters would fall off line. A year or so > before I'd been told by another SMA representative that generator circuit > boards had been fried by inverter backfeed. > > It would be very good to get to the bottom of this one. >
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