Solar panel not putting out

[learning all the time]

Hopefully my title sparks interest. I am running 500w of solar panels. 2 renogy eclipse hard solar panels and 3 rich solar flexible panels. The renogy I have had for two years and the rich solar I am in the process of adding. The two renogy and 1 rich solar connect to my mppt controller without problems-- a little inefficient but that is a flat roof problem I believe-- two of the rich solar panels do not connect. I get 21.5 voc on both and 5a imp. When I try to run these in parallel I lose voltage and amps. I tried running the two rich solar each indivually and the controller says mmpt waiting to charge. I tried series between the two and the same thing. I do have extensions on the two bad solar panels but again, everything seems to test good through the connectors. Any thoughts or ideas or another test I can try? All help is wonderful.

 

[gnubie]

Can you draw up a simple diagram of how you are connecting things? It's easy to get exactly how you are connecting up the panels confused from what you've said. What is your battery voltage? 12, 24, 36? If you have batteries in series the voltage across the batteries is what matters. A single 12V battery is 12V, two in series is 24V etc.

 

[learning all the time]

Here it is. Just trying to run 5 panels in parallel to a 12v battery system. 2 280ah 12v batteries in parallel.

 

[gnubie]

OK, much clearer. When hooking panels in parallel you need to pay attention to the voltages. Can you post a link to both types of panels specs or failing that post the Voc, Vmp and Imp rating for both types from the labels on the back?

 

[learning all the time]

rich solar:

• Maximum Power(Pmax): 100W
• Maximum Power Voltage(Vmp): 18.7V
• Maximum Power Current(Imp): 5.35A
• Open Circuit Voltage(Voc): 22.3V
• Short Circuit Current(Isc): 5.70A
• Maximum System Voltage(Vmax): 600VDC
• Temperature Range: -40°C ~ 85°C
• Maximum Series Fuse Rating(A): 15A
• Weight: 4.8 lb
• Dimensions: 41.1 x 27.2 x 0.11 in

Renogy:

Solar Cells: 32 Cells	Cell Efficiency: 22.00%
Maximum Power: 100W	Maximum System Voltage: 600V DC (UL)
Operating Temperature: -40°F to 176°F	Maximum Series Fuse Rating: 10A
Optimum Operating Voltage (Vmp): 17.7V	Open-Circuit Voltage (Voc): 21.2V
Optimum Operating Current (Imp): 5.70A	Short-Circuit Current (Isc): 6.10A
Weight: 15 lbs

The other piece of this puzzle is i tried to run each solar panel individually and still had zero results on the two bad ones.

 

[gnubie]

When you have just one of the suspect Rich panels connected to the controller, what voltage does the controller say the panel is producing? If no power is going to the battery/load it should be up towards 22V. If the SCC doesn't tell you the panel voltage you can use a multimeter on the SCC's solar input terminals to check it.

Is your battery fully charged, if so can you put a load on the system so that something can draw power from the SCC? If there isn't a load taking power the SCC will not show any power being produced.

 

[learning all the time]

So I think I found my issue. Even though the cables test good with a multi meter and amp meter my system does not like them. I disconnected and went straight to one of the rich solar panels giving me trouble and its good. I will have to get back to this on Monday as I work the weekend. I should get some time to work on cabling this weekend. Thanks for your help gnubie.

 

[RCinFLA]

Rarely putting different manufactures panels in parallel will yield good results. You are mixing 32 series cell mono panels with 36 series cell mono panels in parallel panel configuration.

The Renogy 32 cell mono panels are odd balls having too low a voltage to run an MPPT controller on non-series connected panels to a 12v battery. I would bet your MPPT controller is just operating in PWM mode as the 32 cell panels likely don't have enough voltage overhead above batteries to run in MPPT mode. At the least it is unlikely the MPPT controller will be able to find the optimum MPPT point with so little overhead voltage from panels.

The Rich panels are 36 series cell mono panels. Their optimum Vmp will never be reached when put in parallel with lower Vmp Renogy panels.

You would be better to run panels in series. Just make sure you don't exceed max MPPT controller input voltage with cold Voc total.

 

[heatwave]

I realized a similar issue on 2x 100w panels that are moved around often at home, disconnecting and reconnecting the MC4 plugs. Two of 10 panels have very loose wring connections, that are pulling free from the crimp inside the MC4. Hard to see that the crimp is weak and the wire has pulled out from connecting. It is only about a 1/4" difference when not making a connection to push the wire back into place; hard to see for sure when a meter isn't on hand.

 

[tictag]

I would buy another SCC and connect both your dissimilar panel strings in series to each. A recommendation for a second SCC might be the Victron 75|15 at about $100.

 

[learning all the time]

I would buy another SCC and connect both your dissimilar panel strings in series to each. A recommendation for a second SCC might be the Victron 75|15 at about $100.

Yeah this is an option for me. I am thinking maybe a second SCC but not hooked up and I can just switch from the house batteries to the engine battery and keep everything charged. The other option is a 6th panel and a series parallel scenario

 

[learning all the time]

I realized a similar issue on 2x 100w panels that are moved around often at home, disconnecting and reconnecting the MC4 plugs. Two of 10 panels have very loose wring connections, that are pulling free from the crimp inside the MC4. Hard to see that the crimp is weak and the wire has pulled out from connecting. It is only about a 1/4" difference when not making a connection to push the wire back into place; hard to see for sure when a meter isn't on hand.

I do believe this is what is happening. I had some older mc4 connectors (not sure of the brand) and they were a little tough to deal with.

 

[learning all the time]

Rarely putting different manufactures panels in parallel will yield good results. You are mixing 32 series cell mono panels with 36 series cell mono panels in parallel panel configuration.

The Renogy 32 cell mono panels are odd balls having too low a voltage to run an MPPT controller on non-series connected panels to a 12v battery. I would bet your MPPT controller is just operating in PWM mode as the 32 cell panels likely don't have enough voltage overhead above batteries to run in MPPT mode. At the least it is unlikely the MPPT controller will be able to find the optimum MPPT point with so little overhead voltage from panels.

The Rich panels are 36 series cell mono panels. Their optimum Vmp will never be reached when put in parallel with lower Vmp Renogy panels.

You would be better to run panels in series. Just make sure you don't exceed max MPPT controller input voltage with cold Voc total.

Thank you. I realized there would be some trade offs. My first step is to get all the panels to work. Second step is to optimize which may be a second SCC and a 4th solar panel