Hi William - This article is a few years old, but I think describes ground fault detection issues well: http://www.solarabcs.org/about/publications/reports/blindspot/pdfs/inverter_groundfault-2013.pdf
I don't have experience (at least since the late 90s) with the type of GFD breaker you describe on the DC-side PV circuit. We switched to AC coupled systems with standard grid tied inverters (transformerless non-isolated) years ago. What kind of setup are you referring to? Best, August Luminalt On Mon, Jul 22, 2019 at 1:42 PM William Miller <will...@millersolar.com> wrote: > Wrenches: > > > > Here is a question that has bothered me for some time: If one is using a > GFD (ground fault detection) breaker on a PV feeder(s) to a battery > inverter system, the state of the industry is to use a breaker with an > extra 0.5 or 1 amp pole. This section of the breaker connects, or bonds > the DC negative, or grounded conductor, to the grounding system. > > > > In order for the GFD breaker to work one needs to isolate the grounded bus > bar (negative). If there is a ground fault the breaker opens and breaks > the bond. > > > > This goes very much against my conceptualization of how a bonding system > should work. The bond should never be broken, particularly when there is a > fault in the system. When this breaker opens, either manually or by an > overcurrent condition on any pole, the DC bond is removed for all portions > of the DC system. > > > > There is a prominent personality in the industry that often presents > academic opinions on solar related electrical issues in articles and in > seminars. This person claimed to have invented this GFD system, but when > pressed to comment on the concerns mentioned above, changed the subject. > > > > I believe ground fault protection is important. I just don’t believe the > method the industry has offered is really effective in solving the issues > presented in a ground fault scenario. > > > > I believe similar issues present on non-battery PV systems with the simple > fuse in the ground system found on many inverters. I know some > troubleshooting guides warn of energized parts in ground fault conditions. > > > > Have any of you thought about these concerns? Are my concerns valid? > What are your policies on this subject? > > > > Thanks in advance for any insight. > > > > William Miller > > > > Miller Solar > > 17395 Oak Road, Atascadero, CA 93422 > > 805-438-5600 > > www.millersolar.com > > CA Lic. 773985 > > > > Quote of the month: “As they age, batteries transition from energy > > storage devices to energy consuming devices.“ W. Miller > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
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