FYI Sol Ark sales engineer has suggested the following: “For the 15K, we've recommended AcuCT R Series - AcuCT-4161R-800:100mA | Accuenergy <https://shop.accuenergy.com/product/acuct-4146r-800a-100ma/> with 100mA output.
On the inverter, you will need to adjust the CT ratio to 8000:1. Also note that this will have to be confirmed with Tech Support upon installation/commissioning, to prevent void of warranty.” The CT has an ID of 4” so all parallel conductors should pass through just fine. The 30 and 60K units use a similar Accuenergy CT but higher amp draw that are not compatible with residential units. On Thu, Jul 18, 2024 at 11:51 AM Dan Lepinski, P.E. <d...@ntree.org> wrote: > Chris, > > If the only goal is to avoid backfeeding the grid, in the configuration > as described, the inverter will sense any outbound current and reduce its > output accordingly. > > Should you desire to monitor incoming power and energy, all readings will > need to be multiplied by three .. which unless there's a specific setting > in the inverter to automatically allow this scaling (unlikely, and requires > Sol-Ark verification), such multiplications will need to be consciously > performed when looking at the data. > > Not ideal from a data tracking perspective, but it will at least meet the > zero-backfeed stipulation. (You may want to discuss adding bi-directional > CT "current scaling" capability with Sol-Ark if it doesn't already exist in > their firmware.) > > > Dan > > > > On 7/18/24 10:24, Chris Sparadeo wrote: > > Hi Dan, > > > > Thanks for your thoughts. The idea of 1/3 CT crossed my mind as well. > The question is how to set up the inverter with a 3x multiplier on those > two CTs to get a full 800A reading. I assume that would be something a Sol > Ark engineer would have to program remotely? > > > > Thanks again, > > > > -Chris > > > > On Thu, Jul 18, 2024 at 8:42 AM Dan Lepinski, P.E. <d...@ntree.org > <mailto:d...@ntree.org>> wrote: > > > > Gentlemen, > > > > A possible solution is to utilize one CT around one each of the > three paralleled 400 MCM. One CT around one of the three L1 conductors, > and the other CT around one of the three L2 conductors. Ensure correct > direction for current flow when you install them. (Sol-Ark calls it > "polarity".) > > > > With three 400 MCM in parallel, each conductor will carry nominally > 1/3 of the total current, regardless of direction (in or out). Thus a CT > around each of the three phase conductors will measure 1/3 of the total > current. > > > > 800 Amps / 3 = 266.67 amps. > > > > As you probably know, there's a 200 amp CT and 600 amp CT on > Sol-ark's website. https://shop.sol-ark.com/catalog/extra-large-cts/ < > https://shop.sol-ark.com/catalog/extra-large-cts/> > > > > Obviously the 200 amp CT isn't suitable (267A > 200A), which leaves > the 600 amp part. > > > > Program the inverter accordingly, with an understanding the 600 A CT > will be reading 1/3 of the total current. > > > > You'll give up some resolution (267A/600A = 44.4% of the total > full-scale current reading for a 600 amp CT), but with proper inverter > setup, it will work for purposes of limiting export. > > > > That said .. each CT requires its own burden resistor, and the > inverter isn't designed for three to be connected as you're discussing, > whether series or parallel. > > > > > > Hope this helps... > > > > > > Dan > > > > > > -- > > Dan Lepinski, P.E. > > Professional Solar Consultant & Electrical Design Engineer > > Serving the Solar Industry Since 1972 > > www.ntree.org <http://www.ntree.org> > > 817.884.6081 (cell) > > Texas License 123654 > > Texas Registered Firm F-17965 > > > > * United States Department of Energy National Building Codes > Assistance Project > > (One of only two engineers selected nationwide for the program.) > > > > * Voting Member - UL 1741 / UL 62109 Standards Technical Panel > > > > * Voting Member - IEEE 1547 Standards Development Committee > > > > * Voting Member - North Central Texas Council of Governments > Regional Codes Coordinating Committee > > > > * Voting Member - North Central Texas Council of Governments > Electrical Code Advisory Board > > > > * State of Texas Energy Advisory Council Member > > > > * State of Texas Contracted Subject Matter Expert on Solar Energy > > > > * International Code Council Preferred Education Provider (#2882) > > > > Professional Profile: > https://www.linkedin.com/in/dan-lepinski-p-e-5339bb22/ < > https://www.linkedin.com/in/dan-lepinski-p-e-5339bb22/> > > > > "Scientists investigate that which already is; engineers create that > which has never been." > > ~ Albert Einstein > > > > Unless indicated otherwise, all information contained in this > message is privileged and confidential. As such, it is intended only for > use by the addressee(s) named above, and others who have been specifically > authorized to receive it. Correspondence designated as privileged and > confidential is subject to all terms and conditions of any Confidentiality > Agreements and/or Non-Disclosure Agreements in effect between our > respective parties. > > > > > > > > > > > > > > > > On Thursday, July 18, 2024 at 07:04:47 AM CDT, Kirk Herander via > RE-wrenches <re-wrenches@lists.re-wrenches.org <mailto: > re-wrenches@lists.re-wrenches.org>> wrote: > > > > > > > > > > > > > > > As an aside, I ran into this with a Fortress True 12kw. (As of > several months ago) They have not tested parallel CTs, nor have they tested > single CTs in any service above 200A. They would not approve my plan to > parallel CTs on a parallel conductor, 400A service. > > > > > > > > > > Fortress does have an input for a 3rd party meter, who knows if > it's been developed, maybe Sol-Ark does too. > > > > > > > > > > Definitely run it past Sol-Ark first. > > > > > > > > > > > > > > > > > > > > On Thu, Jul 18, 2024 at 7:46 AM Jason Szumlanski via RE-wrenches < > re-wrenches@lists.re-wrenches.org <mailto: > re-wrenches@lists.re-wrenches.org>> wrote: > > > > > You should be able to parallel 6 CTs (3 per phase) as long as you > get the phases and directions right. The question really comes down to > whether the Sol-Ark can handle the current from 800A at the CT ratio (which > I believe is 2000:1). For practical purposes, on an 800A service, > particularly residential, you will probably never see more than 600A, so it > would probably be fine. > > > > > > > > > > But I would like to know what Sol-Ark says about this. It does not > appear to be documented. For the 30K and 60K they have recommended CTs for > up to 1200A. I'm not sure if 600A measurement is a hard limit for the 15K > considering that's the largest single CT they specify in their > documentation. > > > > > > > > > > Jason > > > > > > > > > > > > > > > > > > > > On Thu, Jul 18, 2024, 7:23 AM Chris Sparadeo < > sparadeo.ch...@gmail.com <mailto:sparadeo.ch...@gmail.com>> wrote: > > > > > Hi Jason, > > > > > > > > > > Sorry for not clarifying. This is a export limited scenario, so > CTs would still be required. > > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Jul 18, 2024 at 6:51 AM Jason Szumlanski < > ja...@floridasolardesigngroup.com <mailto: > ja...@floridasolardesigngroup.com>> wrote: > > > > > This may or may not be helpful, but are you sure you need the CTs? > They are not always required. You would need them for power export limiting > or grid peak shaving, but for straight grid-tied with or without battery > backup, you don't need them. > > > > > > > > > > Jason Szumlanski > > > > > Florida Solar Design Group > > > > > > > > > > > > > > > > > > > > On Wed, Jul 17, 2024, 8:41 PM Chris Sparadeo via RE-wrenches < > re-wrenches@lists.re-wrenches.org <mailto: > re-wrenches@lists.re-wrenches.org>> wrote: > > > > > Hey there wrenchers, > > > > > > > > > > I am working on a larger project with 6 Sol-Ark 15K units and an > 800A service. The main service conductors are 3 parallel runs of 400 kcmil. > I am wondering how to CT these conductors from the master inverter. Sol Ark > tech support has not been very helpful so far. I have the included 300A CTs > ....and I do know that they make a 600A CT, but its physical size and > rating aren't a good fit. Does anyone have experience with either a Sol Ark > or third party CT that might fit this 800A configuration? > > > > > > > > > > Kindly, > > > > > > > > > > Chris Sparadeo > > >
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