Cheap and dirty offgrid farmer

[GLC]

Just guessing but maybe heat is the cause. They will produce more in cooler temps? I am not familiar with your controller, maybe some one will chime in that has a suggestion on possible controller settings or controller issues. Wish i could help more. Just wondering what is your controller rated for volts and watt max?

 

[Offgridreefer]

Just guessing but maybe heat is the cause. They will produce more in cooler temps? I am not familiar with your controller, maybe some one will chime in that has a suggestion on possible controller settings or controller issues. Wish i could help more.

I thought of that too. That's why I cooled my panels off with cold water. After doing that the mppt said they were putting out almost 550 watts. My temp gun said they were under 80 degrees at that point. From my research panels typically operate at peak efficiency between 59 and 95 degrees. If that's the case they should have been providing the maximum power that they are capable of producing considering the position and intensity of the sun and the temp of the panels.
I appreciate your help.

 

[GLC]

Just wondering what is your controller rated for volts and watt max?

 

[Offgridreefer]

Just wondering what is your controller rated for volts and watt max?

Max volts for the controller is 150.

 

[Offgridreefer]

Just wondering what is your controller rated for volts and watt max?

Max watts is 800.

 

[Hedges]

Divide and conquer.
(with current flow interrupted first), disconnect one string then operate and note voltage/current readings.
Repeat with other string.
If not same, one panel in a string is low, isolate to find it.

About 5.5A short circuit, did you say? Later, "max power current =5.58 amps"
That's not max current, it is Imp, current at point of maximum power. Another spec would be Isc, short circuit current which you can easily measure.
Probably Isc is about 6.0A
If your measurement of Isc and Voc don't match label, the power extracted by MPPT will be proportionately lower.

Most likely, you just don't have one standard sun, 1000W/m right now.

 

[Craig]

First off 800 watts at 12 volts to the batteries is really close to the limits of the SCC. Secondly panels most likely do not give full output unless they are positioned in the exact angle needed which is really only possible for about an hour a day unless you have a tracker.

BUT you should be seeing more than you are reporting. I agree with hedges above. Try to use half the panels and see what happens do you get the full 400 watts or at least 360 which is what I would expect to get.

 

[ianganderton]

I’ve read through this. Have you checked the voltage and current at the SCC terminals with a multi meter?

While there have been more than just your report of renogy customer service being a bit crap responding to queries in recent times I haven’t seen any issues with inaccuracy but it’s worth checking.

If the multi meter agrees with the SCC then it’s an issue with the panels or the wiring. With the levels of missing wattage though the wires world be pretty damn hot.

Could one of the panels be damaged? I’d be trying to check the output of each panel (both voltage and current). A clamp meter would be useful for this. Maybe disconnecting one string and then the other to see if there is a difference between them.

One shaded cell could cause this kind of wattage drop couldn’t it? Therefore so could a damaged one.

 

[snoobler]

I concur with Hedges for diagnostics.

Another common cause: batteries that are in absorption mode before peak output, i.e., if you're in absorption by 10 or 11 in the morning, your SCC is limiting the power it pulls from the controller. When we're away and only pulling 100W overnight, my 3kW array rarely shows more than 1800W of output because it's in absorption mode by 8-9am.

If your floating or in absorption at high noon, hit your system with as large a load as you can ( higher than your array wattage) ... see what the panels will produce then.

 

[Hedges]

Like snoobler said.

Your picture of charge controller showed "100%" on battery. So it was just doing its job, limiting what power was drawn from the panels.

 

[tazmann]

I get about the same results , I can get the rated amp output of the panel but the watts are pretty much always 70% or less does not matter if I run single 100 watt panel at 12 volt or 4 of them parallel, same results with 800 watts 2S 4P at 24 volt . At best I have got up to 75% but not often

 

[Hedges]

I get about the same results , I can get the rated amp output of the panel but the watts are pretty much always 70% or less does not matter if I run single 100 watt panel at 12 volt or 4 of them parallel, same results with 800 watts 2S 4P at 24 volt . At best I have got up to 75% but not often

OK, always a reduced percentage.
That appears to say the issue isn't that battery is so fully charged no more power is needed; that would have been fixed max watts, not fixed percentage.
But try adding a load or draining battery overnight to check.

Probably, either panels only produce PTC = 75% of STC in full sun (would have expected 85%),
Or, you're getting a bit less than full sun. Maybe you have 900 W/m not 1000 W/m. It isn't always obvious, like clouds or dust storms.
If you can get a meter, or find current on-line data, you could check. Otherwise, continuing to monitor may show higher production days.

"I can get the rated amp output of the panel"
Do you mean that in operation the MPPT is reporting panel current equal to Imp? (but at a lower voltage than Vmp)
Or, that you measured Isc matching specs?

Try measuring Isc (current at zero volts) and Voc (voltage at zero amps)
Voc reflects leakage current equal to Isc, due to thermally excited electrons, defects in silicon, etc.
I think Isc will tell you if you have one full sun an full current production from the panel, but is unaffected by leakage current.

 

[tazmann]

OK, always a reduced percentage.
That appears to say the issue isn't that battery is so fully charged no more power is needed; that would have been fixed max watts, not fixed percentage.
But try adding a load or draining battery overnight to check.

Probably, either panels only produce PTC = 75% of STC in full sun (would have expected 85%),
Or, you're getting a bit less than full sun. Maybe you have 900 W/m not 1000 W/m. It isn't always obvious, like clouds or dust storms.
If you can get a meter, or find current on-line data, you could check. Otherwise, continuing to monitor may show higher production days.

"I can get the rated amp output of the panel"
Do you mean that in operation the MPPT is reporting panel current equal to Imp? (but at a lower voltage than Vmp)
Or, that you measured Isc matching specs?

Try measuring Isc (current at zero volts) and Voc (voltage at zero amps)
Voc reflects leakage current equal to Isc, due to thermally excited electrons, defects in silicon, etc.
I think Isc will tell you if you have one full sun an full current production from the panel, but is unaffected by leakage current.

Yes I can get the amps a little over Imp but the voltage is less than the Vmp, has to be or the higher voltage would cook the batteries . I kinda figure it is what it is because I live in the central valley of California , lots of farming and dust topped with smog. At the moment you would be doing good to get 40% with all the fires going and smoke in the sky