Thank you William, I stock those breakers in large numbers and purchase them from the manufacturer. We're it not that I leave in 10 hours for the rest of the winter I would have just sent a bunch to Jay, but time is of the essence. That is the only reason for the (poor) recommendation.
Best, Daryl On Thu, Jan 18, 2024, 2:57 PM William Miller via RE-wrenches < [email protected]> wrote: > Friends: > > > > I am not familiar with the inverter cited and I am not going to take the > time to research it. There are too many options this day to keep up! > > > > If this system requires load disconnecting, a touch safe fuse holder is > not the correct device. They are not rated for load break. A work-around > is to plainly indicate the inverter AC disconnect should be activated or > the inverter turned off before opening the fuse disconnect. > > > > Also, please consider not shopping at Amazon. They have a terrible record > regarding employee safety. PV-Cables carries this fuse holder at a > competitive price and they are great people to work with. Here is a link: > https://pv-cables.com/product/littelfuse-spf-solarfuse-holder/. There > are many other solar vendors that have these and that could use your > shopping dollars. > > > > Below are some related subjects I have been pondering: > > > > RSS as PV disconnecting means: > > > > I have been whining at great length about having to install RSS MLPE on > off-grid installations. My most pathetic whining has been about having to > install these on ground-mount arrays. My understanding is that RSS is > supposed to protect fire fighters when they respond to structure fires. > How does an RSS system on a ground mount even apply here? > > > > However, I do find it handy to have an easy way to de-energize PV circuits > so I can safely work in combiners and recombiners. This makes me wonder: > Is module level RSS equipment suitable to act as PV disconnecting means? > > > > Tigo Transmitter-Where should it be installed? And a warning: > > > > I like to be able to measure PV circuits when connected and disconnected. > If the Tigo RSS transmitter donut is installed down-stream of the PV > disconnecting means then open circuit measurements are not possible. If > you open the disconnect, the keep-alive signal goes away and you can’t > measure the PV string. > > > > I got a surprise when doing just this a few days ago. I have two rows of > PV racks and a combiner on each row. If I want injection of Tigo > keep-alive signal upstream of the combiner breakers, I need to install a > transmitter in both combiners. I looped the feeders to the far combiner > through the near combiner. The Tigo donut in the near combiner was near > those looped feeders and induced enough signal in the feeders that the RSS > MLPE in the next rack were switched on. I got a nasty 200 VDC shock out of > the deal. See photo below. > > > > > > Automatic RSS: > > > > As noted above, everything I have read about RSS is that it is designed > for the safety of fire fighters. RSS is a manually activated system. > Someone needs to find and push or twist the disconnect button. If this is > not done the RSS provides no protection. Why could we not require AFCI and > GFDI equipped inverters and charge controllers to provide a contact closure > in case of either fault that could easily be wired into the RSS system to > activate the RSS automatically? Seems like a no-brainer to me. > > > > True PV safety for fire fighters and the public: > > > > I was watching a webinar > <https://www.youtube.com/watch?v=MyBe21Q3xCQ&t=629s&ab_channel=MayfieldRenewables> > on UL 3741 recently. In it the presenter early on makes the claim that PV > systems are “inherently safe” (8:45 in the video). I think this is wrong. > String PV systems are inherently *unsafe*, for two reasons: 1. PV panels > have no off switch. If the sun is shining the panels are creating power, > at potentially fatal levels. 2. PV panels cannot trip OCPD. PV panels are > finite in ampacity and we need the OCPD to be rated at above the available > current. In case of a fault an AFCI or GFDI equipped inverter or charge > controller can detect those faults and shut off, but the fault still exists > and is still being fed power. These concerns apply to PV string systems. > Micro-inverter systems could be argued as being inherently safe. > > > > To get to true PV safety, we need to find a way to shut off power at the > source. If we can trigger MLPE RSS to shut off in the case of detectable > faults, we are much closer to the holy grail of true safety. > > > > The interconnection of AFCI and GFDI inverters and charge controllers with > RSS is one way to achieve this goal. This should be easy to achieve-- it > requires only a contact closure be built into the electronics. Outback’s > FM100 charge controllers have a contact closure that can be programmed to > open in the case of an error, but not the errors we need. So close… > > > > Thinking this through further, why not build AFCI and GFDI protection > right into MLPE electronics? That way in the case of a fault the power is > shut off at the source. Maybe Solar Edge does this already. Does anyone > know? > > > > UL3741: > > > > I have just started studying UL 3741. From what I have learned so far, I > am not convinced this is the right direction. For one, the standard > upgrades the allowed voltage exposure to 160 VDC. Number two, the standard > is written only to protect fire fighters. This leaves out protecting the > public. This includes kids climbing on a ground mount or using a piece of > copper pipe to retrieve a Frisbee from under a PV array, or a homeowner > falling into a PV array while hanging holiday decorations on a dormer-- to > name just a few scenarios. Number three, the goal is to eliminate MLPE. > Until PV panels come with an accessible off switch, we need MLPE. We > cannot have power sources so ubiquitous to our lives that can’t be turned > off. > > > > As an industry, I think we have not prioritized PV safety nearly as much > as the industry does for regular electric equipment safety. If you don’t > believe me, try running conductors to a roof-top air conditioning unit > without conduit protection and see what your inspector thinks about that. > > > > I am interested in thoughts any of you may have on the above topics. > > > > William > > > > Miller Solar > > 17395 Oak Road, Atascadero, CA 93422 > > 805-438-5600 > > www.millersolar.com > > CA Lic. 773985 > > > > > > *From:* RE-wrenches [mailto:[email protected]] *On > Behalf Of *Nick A Lucchese via RE-wrenches > *Sent:* Thursday, January 18, 2024 9:50 AM > *To:* RE-wrenches > *Cc:* Nick A Lucchese > *Subject:* Re: [RE-wrenches] Recommendation on DC Breaker > > > > The Siemens HNF361RPV is worth looking into. Quite affordable and reliable > build quality without having to resort to Amazon. It first appears that > it’s limit is 250 vdc but the footnotes indicate 600 once going deeper into > the details. Obviously not a fuse though. > > > > Nick > > > > > > > > On Jan 18, 2024, at 7:59 AM, Jason Szumlanski via RE-wrenches < > [email protected]> wrote: > > > > Thanks, all, for the quick recommendations. I believe an isolator like the > IMO is technically all that is needed since it is a current limited circuit > and OCPD shouldn't be required, but the manual calls for a circuit breaker. > That is probably just a semantics issue. > > > > On the other hand, the 1000V DIN rail breakers on Amazon are a dead cheap > option and worth considering, too. > > > Jason Szumlanski > > Principal Solar Designer | Florida Solar Design Group > NABCEP Certified Solar Professional (PVIP) > Florida State Certified Solar Contractor CVC56956 > > Florida Certified Electrical Contractor EC13013208 > > > > > > On Thu, Jan 18, 2024 at 10:48 AM Jay via RE-wrenches < > [email protected]> wrote: > > I’d use an IMO disconnect as you don’t have any current limitations. > > > > I think sometimes things get lost in translation. > > > > Jay > > > > > > > > On Jan 18, 2024, at 8:43 AM, Jason Szumlanski via RE-wrenches < > [email protected]> wrote: > > > > I am installing an EG4 off-grid 3k inverter for the first time, and the > manual requires a DC circuit breaker on the PV input. It will be a small PV > array with adjusted max Voc around 280V @ Isc 10.6A. > > > > I'm looking for a cost-effective DC breaker and enclosure for this purpose. > > > > Jason Szumlanski > Principal Solar Designer | Florida Solar Design Group > NABCEP Certified Solar Professional (PVIP) > Florida Certified Solar Contractor CVC56956 > Florida Certified Electrical Contractor EC13013208 > > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. 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