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

[MTM98290]

I have 2 25w panels in series. The made 13.19v separately, in parallel, and in series. What am I missing?

I am using a Victron 100/15

 

[sunshine_eggo]

Have you confirmed their Voc values individually with a voltmeter?

13.19V for a solar panel is VERY low.

 

[740GLE]

Are you reading battery voltage or PV voltage on the victron unit?

 

[MTM98290]

The voltmter seemed to deplete them to 0v

Are you reading battery voltage or PV voltage on the victron unit?

Yes I was reading the victron units voltage. I put a voltmeter on it but it seemed to be putting out 14-16 volts but the voltmeter seemed off as the voltage would drop to 0 a moment after connecting. I could break contact like slow pwm and could read voltage. I will try again with better light.

The charge controller works well for monitoring battery voltage from upstairs and for controlling a light. I was hoping to use solar panels on it to give a day night signal for streetlight mode, and hopefully offset the consumption of the scc.

This gives me a connection to the system via bluetooth when the AC charger is powered on and the SCC is always available to check on system. This makes for nice redundancy.

 

[740GLE]

So you were reading the panel voltages with a meter while they were still connected to the Victron SCC?

So you weren’t measuring VOC, or did you turn off charging of the SCC while measuring the voltage?

Typically victron units keep the solar PV voltage 5v higher than the battery, for your case it might be pulling the PV voltage down even lower.

Also can you post a screen shot of the Pv voltage trends of say the past day or so?

 

[Mattb4]

Can you give the brand and model of your solar panels? Hopefully they are not one of those units designed to charge a battery and thus have a built in SCC.

 

[MTM98290]

https://a.co/d/54rdNqg

Does this link work? It works on my end, but it doesn't look right to me.

 

[740GLE]

How are you making the connections between panels? Are you still using those SAE connectors?

 

[MTM98290]

So you were reading the panel voltages with a meter while they were still connected to the Victron SCC?

So you weren’t measuring VOC, or did you turn off charging of the SCC while measuring the voltage?

Typically victron units keep the solar PV voltage 5v higher than the battery, for your case it might be pulling the PV voltage down even lower.

Also can you post a screen shot of the Pv voltage trends of say the past day or so?

 

[MTM98290]

So you were reading the panel voltages with a meter while they were still connected to the Victron SCC?

So you weren’t measuring VOC, or did you turn off charging of the SCC while measuring the voltage?

Typically victron units keep the solar PV voltage 5v higher than the battery, for your case it might be pulling the PV voltage down even lower.

Also can you post a screen shot of the Pv voltage trends of say the past day or so?

No I tried reading voltage separate from SCC.

Then I hooked up SCC. I never had to turn of charging because it was too low to allow any.

The panels should make up to 20vx2 so I should have 32v @ 0.7v right now in our bright overcast weather..

 

[MTM98290]

Trends screen

 

[MTM98290]

How are you making the connections between panels? Are you still using those SAE connectors?

It is still in test mode which means the bare wires are twisted together. I have them in series now, which gives same voltage as parallel.

 

[740GLE]

Can you share a picture of how you made the connections between the panels?

And to confirm you took just one panel, not connected to anything and under decent sun still only saw 13.xx volts?

 

[Mattb4]

https://a.co/d/54rdNqg

Does this link work? It works on my end, but it doesn't look right to me.

Yes I can see the panels on Amazon. Since they have a Voc of 22.41 and a Vmp of 18vDC you should see around 42vDC on your DMM before connecting to SCC when in series. When connected it should still be in the 36-38vDC range if you have good sunlight.

It sounds like you have bad panels.

ETA: it is also a possibility if you test both panels individually and they are good you are not wiring them properly such as pos to pos and then trying to output from the negative leads. Or vice versa. Series requires 1 pos to the next panels neg. Parallel would require pos to pos and neg to neg.

 

[MTM98290]

I have had them both ways. The numbers from th SCC;
1st panel 13.6v
2nd panel 13.6
2panels in paralell 13.6
2panels series 13.6

Voltmeter says 12.96

 

[MTM98290]

If i hook them up backward the diodes do block continuity.

 

[MTM98290]

Can you share a picture of how you made the connections between the panels?

And to confirm you took just one panel, not connected to anything and under decent sun still only saw 13.xx volts?

They can make more than 13.6 but don't seem to once hooked to the scc.

They are reading 19.97v unhooked.

 

[740GLE]

Trends screen

Can you zoom out and show the entire day?

 

[740GLE]

They can make more than 13.6 but don't seem to once hooked to the scc.

They are reading 19.97v unhooked.

So reading 19.97 is the VOC.

Again can you take a picture of the wiring by the panels?

How far away are the panels from the SCC? How far away is the SCC from the battery?

What’s the conductor you are using?

 

[MTM98290]

I am using copper. 6ft long.scc is 2 ft from battery.