Victron 250/100charge controller lowers PV input voltage?

[Colby Self]

I have a Victron 250/100 charge controller. I am getting 87v 10A to the controller but it lowers the voltage to 67v 10A. Is this the MPPT finding the right combo of volts and amps? My solar set up is 4 Ecoworthy 195W monocrystalline VOC 24.5/ ISC 10.14A in series then in parallel with 4 HQST VOC 24.3 ISC 5.5A panels also in series. All running through 10 AWG PV wire. I am open to suggestions to maximize my production. We have also had temps high as 108 for many days.

 

[Mattb4]

Let me see if I understand you. You have 4-195w panels in series and than 4-100w panels in series that you paralleled them together? The results are 689w. Having such a mismatch of high wattage string with low wattage is reducing your possible output. Your better bet would to be to parallel 2 of the 100w together to get an equivalent 200w panel (X-2). This can than be connected with 200w panels (either is series or parallel) depending on max voltage you need to stay under.

 

[MisterSandals]

Is this the MPPT finding the right combo of volts and amps?

Yes, this is what MPPTs do. I suspect less than optimal sun.

Having such a mismatch of high wattage string with low wattage is reducing your possible output.

I think it is setup correctly for series first to ~96V. Then paralleling strings to add the amps of the 2 strings.

 

[mikefitz]

Check the strings separately, the output is low for 1200 watts of panel.

Having such a mismatch of high wattage string with low wattage is reducing your possible output

With the two strings in parallel with similar string volts, there should not be any issues.
I suspect a problem with one of the strings.

but it lowers the voltage to 67v

This is expected, maximum power could be around 17 volts per panel.

Mike

 

[Mattb4]

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With the two strings in parallel with similar string volts, there should not be any issues.
I suspect a problem with one of the strings.

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Theoretically I agree it should be like two batteries of the same voltage but different capacity. However I have found a production hit anytime I have not kept both voltage and amperage (within a few percent) the same on solar panels setups.