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solarozq

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Posts: 3
Reply with quote  #1 
I have 2 solar strings on one inverter and am interested in the PV values. Both strings are similar but looking at values one shows much higher 370 against 280. The lower value seems to go down with increased solar output 300 to 260. Does this mean anything?

stmbtwle

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Reply with quote  #2 
Voltage WILL drop when you put a load on them, just like a battery. That's normal. The big difference in string voltage would be a concern to me; I'd investigate. What does the inverter manual say?

As the lower-voltage string is only dropping 20v, I'd suspect it's not putting out it's share, and the other string is carrying the load. What is the VOC and the VMP of the strings?

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
solarozq

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Reply with quote  #3 
String 1 Vm 354, Voc 442. String 2 Vm 318, Voc 397.
The actual inverter does not identify which string is which. String 1 (the first installed, a couple of years earlier) is showing the lower values.
Maybe it's possible that the inverter has now selected the first string installed as being the second string?? Growatt Sungold 3000.
At dusk yesterday I inspected and washed the first string installed (dirt but no obvious damage), today I didn't observe any changes to voltage.
The manual doesn't say anything on the subject. 
stmbtwle

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Reply with quote  #4 
I really don't know. Possibly the older string has some corrosion issues but that's just a guess.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
solarozq

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Reply with quote  #5 
Thanks for responding, the panels appear to be clean but corrosion wouldn't be obvious without really close inspection.
I added another panel to the first string, off line it indicated 360 v but when the inverter synchronised it immediately dropped to 300 v. 
The whole system is probably 5-6 years old as the second string was pre used.
With all the panels hooked up I'm now running close to the inverter rating (3000 w) which is good.
I have 12 v cooling fans fitted around the inverter to keep its temperature reasonable. 
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