[RE-wrenches] Efficiency Curves of Fronius Inverters?

Bill Brooks billbrooks7 at yahoo.com
Thu Jul 9 20:25:23 PDT 2009


Peter,

 

All of the events I saw were similar to each other and different from your
experience. What I saw was the inverter operating 40Volts above Max Power
Point (MPP) (it was at 330V when it should have been at 290V). This caused
the inverter to operate at 90% of what a properly operating inverter would
produce. After cycling the inverter off and back on, most went to the proper
MPP, but some went back to the wrong voltage. The consistency is uncanny and
not encouraging. It looks like they have a software problem. It's likely
other inverter companies have similar problems, but to catch a problem after
so little investigation is depressing.

 

We really need a solid MPP tracking test to catch these issues before they
go out broadly into the field. Everybody likes to talk about inverter
efficiency. What is the efficiency of a 95% efficient inverter producing 90%
of available power. Effectively it is 0.95 x 0.90 = 0.855. Nobody would ever
buy an inverter with an 85.5% efficiency, but apparently it happens
regularly.

 

Bill.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Peter
Parrish
Sent: Thursday, July 09, 2009 8:19 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Efficiency Curves of Fronius Inverters?

 

I have a decidedly skeptical opinion of the Fronius MPP algorithm. A few
years ago, I was one of the first (I believe) to notice a curious
"continuous saw tooth ramping" of the DC current and voltage on a couple of
Fronius IG4000's. The problem (I was told by Fronius) was triggered by an
increasing Vdc crossing 240 V (the "line voltage"). The problem was fixed by
a SW upgrade. Ignoring the fact that 240 Vac is not a fixed value, the
standard Fronius IG inverter line may have a generic challenge when Vmp is
in the 240 V range. Was this the case?

 

- Peter

 

Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com  
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885


 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Bill Brooks
Sent: Wednesday, July 08, 2009 4:20 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Efficiency Curves of Fronius Inverters?

 

Mark and Jeff,

 

To be clear, manufacturers do not supply the data. It is required to be
tested by a Nationally Recognized Testing Laboratory (NRTL). Mark's message
could be misconstrued as the data being something Fronius cooked up.

 

On another note. Anyone notice Fronius inverters having trouble finding max
power? Of the 10 Fronius inverters I have looked at in the past 2 weeks, 4
were operating at a voltage well above max power and losing about 10% of the
available array power.

 

Bill.

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Frye
Sent: Wednesday, July 08, 2009 3:43 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Efficiency Curves of Fronius Inverters?

 

Jeff,

 

Here is what they submitted to the California Energy Commision:

 

http://www.gosolarcalifornia.ca.gov/equipment/inverter_tests/summaries/Froni
us%20IG%204000.pdf

 

 

Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
 <http://www.berkeleysolar.com/> www.berkeleysolar.com  

 

 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jeff
Clearwater, Village Power Design
Sent: Wednesday, July 08, 2009 3:35 PM
To: RE-wrenches
Subject: [RE-wrenches] Efficiency Curves of Fronius Inverters?

Hey Folks,

 

Anyone have or know where I can get my hands on the efficiency vs. wattage
curve for the Fronius IG series (the old series - not the Plus).

 

I have a 4000 in stock and wondering if I can apply it to a friend's 2660
watt system without losing much to efficiency at low power levels.

 

Best,

 

Jeff

 

 

 

There are numerous options here:  most ground mount manu's offer ballasted
systems, I would look to them 1st. Other systems I've seen or used - 1) Pour
a continuous surface "footer" that is large enough in size to provide the
proper ballast for the uplift in your area, pour one along the S. edge/legs
and another along the back/north legs. 2) Tie all legs together via a horiz.
rail at least 6' wide and embed this in a rock filled gabion, again of the
required weight. 3) Limestone is easy to drill, useing a hammer drill and
extension bit drill 11/16" - 3/4" holes at least 18" into the stone at an
angle, vary all angles as viewed in plan as they relate to the N/S line of
the array (not as they relate to level), to mitgate pull-out from them all
being in a line. i.e. - 1st leg hole is 90 degrees to the N/S line, 2nd leg
is 180 from this, 3rd is 45 and so on, in other words if looking in plan and
you could see all holes they would radiate around the "face of a clock" with
each leg hole on a different "hour". Finally, epoxy in 5/8" all thread, you
can pre-bend the end to come out of the hole verticle or use a swivel
connector from Uni-strut, B-line or equal.

All of these suggestions should be run by a Structural Engineer before
embarking, thus the 1st choice of working with a manu.


 

Good luck!

-jeff o

>From the Solar, Wind and Hydro powered office of Jeff Oldham/Regenerative
SOLutions



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-- 

~~~~~~~~~~~~~
Jeff Clearwater
Senior Design Engineer
NABCEP (tm) Certified Solar PV Installer
http://www.nabcep.org/
Village Power Design/NorthEast Solar Design
Turnkey Solar Design & Installation for the Commercial Sector
http://www.villagepower.com
gosolar at villagepower.com

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