[RE-wrenches] UPS disturbance with SMA Inverters

Chris Mason cometenergysystems at gmail.com
Mon Aug 4 16:29:57 PDT 2014


Is it possible that the UPS issue is raised voltage, causing the UPS
voltage regulator to switch settings? A large amount of solar on a circuit
can raise the voltage in the system at full sun. I would rent a Fluke
Energy Analyzer and leave it in place for a number of days to see how the
voltage, current and power factor varies with the inverter output.


On Mon, Aug 4, 2014 at 5:11 PM, Carl Adams <swingjunkie at gmail.com> wrote:

> Bob, Ray, Glenn,
>
> Thanks for the responses.  We could cycle through the inverters and see if
> it is one, or some combinations of inverters, which is causing the problem.
>  This results in a minimum of 6 trials.  If it is a combination of
> inverters  many more.
>
> Any feedback on the idea of monitoring the AC circuits; computer feed and
> combined inverter output?  Seems to me this might provide a one step
> correlation between the event and the cause.  Just not sure what equipment
> to suggest for this.
>
> Could be there is some other cause, unrelated to the inverters.  AC unit
> kicking on, etc.  Though they do not see any lights dimiming/brightening,
> or any other notable change in electrical equipment at the sight.
>
>
>
> On Mon, Aug 4, 2014 at 1:03 PM, Glenn Burt <glenn.burt at glbcc.com> wrote:
>
>>  I wonder if the UPS is grumbling about high voltage as the inverters
>> push back current...
>>
>> Glenn
>>  ------------------------------
>> From: Carl Adams <swingjunkie at gmail.com>
>> Sent: ‎8/‎4/‎2014 10:29
>> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> Subject: [RE-wrenches] UPS disturbance with SMA Inverters
>>
>>  Hello Wrenches,
>>
>> I have a site which is experiencing nuisance disturbance of the computer
>> UPS systems at the site.  The site owner "suspects" this is due to the PV
>> system which is a 50 kW system using 6 SMA SunnyBoy inverters.  The
>> nuisance disturbance is a clicking noise in the UPS units.  The disturbance
>> is not enough to cause the UPS to engage, so it seems to be a small
>> disturbance on the AC power.   The site owner "suspects" the inverters are
>> the source of this disturbance since 1) It seems to only occur when we have
>> a good solar day.  2) If the inverters are shut down the problem goes away,
>> and if you start up the inverters the problem exhibits again.
>>
>> The site was commissioned in March of 2012 and has had no problems till
>> this issue last month.  In reviewing the event log on Sunny Portal there
>> are no inverter anomalies.  SMA tech support had not run into this issue
>> and had no ideas, they too agree the inverters are not reporting any
>> anomalies.
>>
>> The problem is not persistent but rather intermittent making this harder
>> to troubleshoot.
>>
>> So my questions are
>> 1) Has anyone else seen this sort of issue before, related to SMA
>> SunnyBoy inverters.
>> 2) Can you recommend an AC power monitoring tool which would support
>>  frequency and voltage monitoring on the AC line.  Perhaps one data set on
>> the circuit feeding the computers and another on the inverter output
>> circuit.
>>
>> For clarity the six SunnyBoys feed into an AC Combiner panel which
>> backfeeds into the building main distribution panel.  The service is
>> 240V single phase.
>>
>> With Regards
>> Carl Adams, SunRock Solar
>> NABCEP Certified PV Installer
>>
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-- 
Chris Mason
NABCEP Certified Solar PV Installer™
Solar Design Engineer
Generac Generators Industrial technician

www.cometsolar.com <http://www.cometenergysystems.com>
264.235.5670
869.662.5670
Skype: netconcepts
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