2s 25w panel makes same voltage as 1 panel?

[Hedges]

I moved plug into 5A. It showed 0.02A
It as a $5 dmm so who knows. I trust the voltage as I have used it for voltage, continuity and ohms, I trust that these functions to be close. I am not sure that I trust the 5A measurements it gives.

Without even using SCC, you need to measure Voc, Isc, V(load), I(load).
We usually say Vmp and Imp, but that means something like MPPT with a place to send the current.
A suitable resistor can provide load.

 

[740GLE]

What are your charge settings in the victron app?
Have you tried removing whatever is connected to the load port on the mppt?

If the MPPT had the charging disabled (low temp protection) wouldn’t we see the PV voltage rise to that 34v that was measured earlier?

 

[740GLE]

1 voltage reading In Victron 100/15

2 Series wiring to sccc

3 series wiring

4 series wiring voltage when not attached to scc

Can you do a screen shot of the SCC settings?

 

[42OhmsPA]

If the MPPT had the charging disabled (low temp protection) wouldn’t we see the PV voltage rise to that 34v that was measured earlier?

I'm not super familiar with Victron, yet.
It's well past sunset, I just went in and disabled charging then re-enabled.
I have 720W panels connected, 82VOC.


I'm convinced the OP has a wiring issue or bad panel.

 

[740GLE]

I'm not super familiar with Victron, yet.
It's well past sunset, I just went in and disabled charging then re-enabled.
I have 720W panels connected, 82VOC.
View attachment 195336
View attachment 195337
I'm convinced the OP has a wiring issue or bad panel.

Yeah I’m 95% as well, but one last check is those setting, the gear in the upper right.

 

[MTM98290]

Yeah I’m 95% as well, but one last check is those setting, the gear in the upper right.

it is not a wiring issue. We are talking about 1.54A At 20v.

Even when I attached a battery, and one panel directly @ 20v to scc the voltage drops to 13.3v.

The settings are default with low temp cutoff @40°f can't take pictures because its all put away at the moment.

2 bad panels seems unlikely, but stranger things have happened.

I have a cheap pwm scc coming tomorrow. Hopefully it is more appropriate for these small panels.

 

[MTM98290]

What are your charge settings in the victron app?
Have you tried removing whatever is connected to the load port on the mppt?

The charge settings are default with a 40°f low temp protection.

 

[MTM98290]

I was able to charge the batteries today. After some delay and a lost controller later was able to get a proper charger to make these panels work. The $11 Renogy pwm scc was hooked up with panels in parallel and functioned as expected.

An mppt charger controller would be neat, but they have the issue of needing 5v over battery voltage to start. Connecting panels in series should really work to mitigate this issue but both Victron units that I tried would pull voltage down to just below battery voltage. This is a mystery to me. I do wonder If a 24v battery would work, but who knows.

This may be the rare time that one needs to swap out their Victron for Renogy to get the desired result.

 

[MTM98290]

I was able to hook up the Victron 75/15 today. It was overcast and raining off and on. For some reason it was able to charge the battery both in series and parallel. I used a parallel configuration until it was too dark to charge. Then I switched the panels to series to see if it would charge, it did not. I then switched to the Renogy PWM and it continued to show that it was charging, but I don't know how much.

I am not sure why this worked today but not the other two times that I attempted the same. My best guess is that it was just too overcast to function.

As a side note; the 75/15 seemed to sweep much lower than 5V above battery voltage and continued outputting a whopping 0.5A-0.6A.
It seems that it may take battery Volts + 5V to initiate charging but it can swing lower looking for the max power point.

I will attempt the same with the 100/15 and see if works the same way.

 

[sunshine_eggo]

+5 Voc to start
+1-2Vmp to keep charging.

 

[MTM98290]

+5 Voc to start
+1-2Vmp to keep charging.

Great, thank you.

 

[MTM98290]

For future readers of this thread I should give a conclusion. Both the 75/15 and now the 100/20 (I exchanged the 100/15 for the 100/20 for the 48v option) are able to charge off the small panels without issue.

Victron Mppts will pull the voltage close down to battery voltage if the have enough voltage but not enough current. This makes it seem as if it should work, but panels seem to be able to make a fair amount of voltage at almost no current flow, so it was misleading to me when I first started using these.

They are great and adaptable to many uses, especially since they don't require the battery to be hooked up to function.