[RE-wrenches] Integrating Fortress E-vault maxes into an SI AC-coupled system

[William Miller]

Friends:



I am still working on getting the E-vaults to play nice with the Sunny
Islands and Sunny Boys.



With Open loop I was getting significant discrepancies in the reporting of
SOC in the e-vaults versus that reported by the SI inverters.  This
discrepancy did not diminish over time.  The discrepancy caused
unacceptable charging and generator operations.



I got Closed loop hooked up, but I found that every few days the SI
inverters would shut down due to a battery over-voltage condition.  I
believe that when the e-vaults are near 100% SOC the BMS units increase the
battery impedance which means any charging current applied will cause the
voltage spike I have been seeing.   I was able to measure these conditions
myself on site, although they were very fleeting and required recording
with the Fluke87 Min-Max function (love this meter!).



I was able to extract log files from the Sunny Island primary inverter and
perform some analysis.  It appears when I turned on remote BMS on the SI
(as part of the Closed loop protocol) it disabled the Frequency-Shift Power
Control.  This means the SI inverters have gone from having poor control
over battery charging to having no control over battery charging.



I have documented my research here
<https://millersolar.com/MillerSolar/case_studies/36_SIFortress/36_SunnyIslandFortressIntegration.html#Inhibit>.
There is a table of contents to take you to the latest information.  I
appreciate pertinent comments any of you might have.



By the way, if anyone has called SMA tech support for help on a Sunny
Island system, you have likely been asked to extract log files, zip them up
and send them off for review (and waited a long time for a reply).  I am
the kind of guy who does not like to wait for solutions and who likes to
figure out things for himself.  I have taught myself how to evaluate those
log files. I will be posting a web page on the subject.  In the meantime,
if you are interested, two of my analysis Excel sheets are linked in the
case study.  I will be expanding on this and providing resources to any
integrator that wants that knowledge.



Thanks in advance for any insight.  I hope I am wrong about this and I am
just missing something.  I also hope revealing my headaches will help
someone someday…



William



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985
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