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Forum Index : Solar : fronius inverter "min" input from PV`s

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rgormley
Senior Member

Joined: 22/02/2006
Location: Australia
Posts: 245
Posted: 09:54am 30 Mar 2009
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I have ordered a larger inverter (fronius IG30) for my 2kw system (allowing for expansion later)

i have just spied on the tech specs for the IG30 that it says miniumum input range from 2500-3600 watts

http://www.powerupsolar.com.au/pdf/Fronius-IG-Brochure.pdf

my PV system is only 1980watts

will this be a problem ie: will my PV input drive the IG30 effectivly

help   
 
GWatPE

Senior Member

Joined: 01/09/2006
Location: Australia
Posts: 2127
Posted: 11:15am 30 Mar 2009
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hi Richard,

have a think about what happens every morning and afternoon and on cloudy days to the output power levels from a 3600W array? I think you will have answered your question re power. peak efficiency may be marginally lower.

Gordon.

become more energy aware
 
rgormley
Senior Member

Joined: 22/02/2006
Location: Australia
Posts: 245
Posted: 12:00pm 30 Mar 2009
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yes, of course....


i feel a bit stupid for asking that one...

 
sPuDd

Senior Member

Joined: 10/07/2007
Location: Australia
Posts: 251
Posted: 10:39pm 30 Mar 2009
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"There's no such thing as stupid questions, only stupid people."
Mr Garrison - South Park   

Fun intended,

sPuDd..
It should work ...in theory
 
rgormley
Senior Member

Joined: 22/02/2006
Location: Australia
Posts: 245
Posted: 10:10am 01 Apr 2009
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ok now for question on adding panels to the fronius inverter
My orig setup will be 11 x sharp 180 watts (1980W 330v)

If i wish to expand to say 3200 watts (funding later)

The fronius has a max input voltage of 450 volts (only has one inpout string) so i presume my panels will have to be broken up and rearanged to a parr/series setup.
9 x series in parr with 9 x series.
this will keep the volts to 270 for the string input.

does this sound correct?
 
micke
Newbie

Joined: 25/10/2008
Location: Australia
Posts: 15
Posted: 12:52am 06 Apr 2009
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Hi Richard.

It is always good to try to keep the Maxium Power Point Voltage in the upper half of the inverter's window to allow for losses.

Allowing for a min temp of -10 and a max of 40 deg C.
and some cable losses 6mm2 for string cable and 10mm2 for array to inverter.

With 11 panels in series        Sting   Array
Power max @ Min Temp         &n bsp;1831.5     1831.5  &n bsp;  Watts     
Power max @ Max Temp         &n bsp;1336.50     1336.50      Watts     
Vmpp @ Min Temp         &n bsp;        271.70     271.70      Volts     
Vmpp @ Max Temp         &n bsp;        216.70     216.70      Volts     
Voc @ Min Temp         &n bsp;        341.00     341.00      Volts     

With 18 panels (2 x strings of 9 in series)
Power max @ Min Temp         &n bsp;1498.5     2997  &nbs p;  Watts
Power max @ Max Temp         &n bsp;1093.50     2187.00      Watts
Vmpp @ Min Temp         &n bsp;        222.30     222.30      Volts
Vmpp @ Max Temp         &n bsp;        177.30     177.30      Volts
Voc @ Min Temp         &n bsp;        279.00     279.00      Volts
     
As you can see on a hot day your Volts at maximum power are only 27 volts above the lower limit for the inverter, which may be the difference between the inverter turning on at 9 in the morning instead of 8 o'clock or the inverter turning on at all on a cloudy day.

The minimum number of series conected 180W sharp panels for this inverter is 8 with a 5% margin
Power max @ Min Temp         &n bsp;     1332   &nbs p; Watts
Power max @ Max Temp         &n bsp;     972.00   &n bsp; Watts
Vmpp @ Min Temp         &n bsp;             197.60      Volts
Vmpp @ Max Temp         &n bsp;             157.60      Volts
Voc @ Min Temp         &n bsp;             248.00      Volts

and the maximum is 15 with a 5% margin
Power max @ Min Temp         &n bsp;     2497.5   &n bsp; Watts
Power max @ Max Temp         &n bsp;     1822.50   & nbsp; Watts
Vmpp @ Min Temp         &n bsp;             370.50      Volts
Vmpp @ Max Temp         &n bsp;             295.50      Volts
Voc @ Min Temp         &n bsp;             465.00      Volts

Mick

          
 
rgormley
Senior Member

Joined: 22/02/2006
Location: Australia
Posts: 245
Posted: 01:02am 06 Apr 2009
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hi mick
the formatting is a little skew....

where did you get this information from???
is there a web site i can visit??
chart to download?

Thanks,
Richard
 
micke
Newbie

Joined: 25/10/2008
Location: Australia
Posts: 15
Posted: 01:22am 06 Apr 2009
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Hi Richard

I have an excel spreadsheet to calculate various data to help with the design of grid connect systems and i cut and pasted those values in sorry about the skewness.

Your supplier or installer should be able to give you some more information on how best to procede in your future system upgrades, but for now 11 series connected panels will work perfectly.

Mick
 
rgormley
Senior Member

Joined: 22/02/2006
Location: Australia
Posts: 245
Posted: 01:25am 06 Apr 2009
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thank you kindly....
 
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