[RE-wrenches] Testing strings with Tigo

[William Miller]

Friends:



We are in the midst of our first off-grid, DC coupled project using Tigo
TS4-A-F RSS switches.



In my few years installing solar I am accustomed to testing PV strings with
a Fluke 87 for Voc, Isc, Vmp and Imp, or some combination.  I do this
regularly in the midst of installing PV so I can be confident once we are
finished there will be no issues with the panels or the wiring.



I understand these tests are not possible with the Tigo units.  With the
circuits unterminated, I can see the 0.6 VDC/Tigo with no keep-alive signal
transmitted.  With the signal being transmitted, I do not see the expected
readings for Voc.  I get only the 0.6/Tigo.  When shorted into the Fluke DC
input the Isc jumps around between 0 and about 2 amps.



I was told by tech support the PV circuits need to be “terminated” at an
inverter before any voltage or current can be measured.  The circuits do
not terminate in an inverter; they will connect to a charge controller
(FM100, in this case).



We have not pulled the PV feeders so connecting to the charge controllers
is not yet possible.  I am nervous about installing the remainder of the
modules without knowing for certain they will produce as they should.



What would you all do to assure yourselves the PV will produce once
connected?



TIA.



William



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985
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