Solar not working

[Purrfecttune]

Had the problem for a few weeks and nothing makes sense.

After changing the connectors for more modern ones where the cable comes into the van it finally started working, and then stopped again after 8 days.
Voltage coming in at the connectors is 21v
Voltage at the MPPT IS 2v

When I upgraded, the original wires from entry to the MPPT were too short, so extended them by 1m using professional clips and quality wire.

Readings at the join are 18v
Continuity from the join to the MPPT is 0 resistance
Reading at the MPPT (with wires plugged in) 2v

What’s going on

 

[Ian_H]

Some pics and more details may help. What was the original setup, the problems with it and the changes made?
A first stab would be run another wire from negative nearest panel to mppt to check no breaks/bad connection, repeat for positive.

 

[Purrfecttune]

I disconnected the Positive wire at the PV on the MPPT and then measured the voltage across the bare wire and the (still connected) MPPT minus PV terminal.

The result was that full charge was being received from the panels (21.8v)

However, plugging the positive wire back in again the reading dropped to 2v

 

[Ian_H]

I disconnected the Positive wire at the PV on the MPPT and then measured the voltage across the bare wire and the (still connected) MPPT minus PV terminal.

The result was that full charge was being received from the panels (21.8v)

However, plugging the positive wire back in again the reading dropped to 2v

So could be a bad connection/partial break that allows voltage measurement when no current flow but drops voltage under load.

 

[NR]

Had the problem for a few weeks and nothing makes sense.

After changing the connectors for more modern ones where the cable comes into the van it finally started working, and then stopped again after 8 days.
Voltage coming in at the connectors is 21v
Voltage at the MPPT IS 2v

When I upgraded, the original wires from entry to the MPPT were too short, so extended them by 1m using professional clips and quality wire.

Readings at the join are 18v
Continuity from the join to the MPPT is 0 resistance
Reading at the MPPT (with wires plugged in) 2v

What’s going on

0 ohms would normally indicate OC However, I note you have 2v, this may be phantom voltage.

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[Purrfecttune]

So could be a bad connection/partial break that allows voltage measurement when no current flow but drops voltage under

So could be a bad connection/partial break that allows voltage measurement when no current flow but drops voltage under load.

You are the second person to suggest that.
So I ran a lead from the negative connector coming into the MH from the panels to the MPPT, bypassing the original wiring - no change.
Did the same again from the positive connector and praise be, solar resumed

Now I just need to route a replacement cable all the way around the MH!

 

[Gromett]

Possibly a faulty solar panel. Shows a voltage under OC conditions, but as soon as a load is applied gives up the ghost.

The only way to test would be to do a short circuit current test I would think? Raul ?

 

[Raul]

Possibly a faulty solar panel. Shows a voltage under OC conditions, but as soon as a load is applied gives up the ghost.

The only way to test would be to do a short circuit current test I would think? Raul ?

Yes, for a faulty panel the short curcuit current reading will be 0, or close to it, but still have voltage.

Also, at the back of the panel, there is a connection box for the wires and cells buss bar. Check the connection in there as well. You will need access under the panel.

 

[Ian_H]

Possibly a faulty solar panel. Shows a voltage under OC conditions, but as soon as a load is applied gives up the ghost.

The only way to test would be to do a short circuit current test I would think? Raul ?

Didnt OP say its working now?

 

[Gromett]

Didnt OP say its working now?

No he said it briefly worked. It is not working again.

and then stopped again after 8 days.

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[Ian_H]

No he said it briefly worked. It is not working again.

Did you read post 6?

 

[Raul]

Did you read post 6?

I did now,

 

[Gromett]

I did now,

Me too. I think I must have opened the post, then not replied immediately and he posted a response in the meantime which I missed.

Sorry Raul

 

[Purrfecttune]

 

[Raul]

Me too. I think I must have opened the post, then not replied immediately and he posted a response in the meantime which I missed.

Sorry Raul

It's OK, I know you had good intentions to help out,

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[Purrfecttune]