2x160w panels not working in parallel

[V8ater]

Hi everyone, I’m facing an issue where I have 2x 160w panels on the roof of my car which are wired in parallel, when assessing the amps together they are making less amps then individually, the panels work perfect individually but when together produce less current.

Both panels have a bypass diode in them, but it seems like when wired in parallel one panel is acting as a load hence taking away almost half of the expected current.

The solar then flows unregulated into a redarc bcdc1240 which is capable of taking up to 28volts.

Any ideas as to fixes will greatly help!

Thanks

[Bala]

How are you doing your parallel load test. Are you sure you are connecting in parallel and not series,?

I have a couple of redarc bcdc units and parallel panels.

[V8ater]

I tested with a multi metre the current from both solar panels flowing through 1 wire and then isolated each panel and saw the current increase as if the other panel was acting as a load. I’m 100% sure it’s in parallel as the voltage is 20-21 volts.

Each panel seems to preform the same, but just when they get connected together the current seems to be restricted.

My solution, though unsure whether it would work is to put some blocking diodes inline as to stop current potentially flowing back up and acting as a load?

[Bala]

Parallel is the + from each panel together and the - from each panel together.

[V8ater]

That’s how it’s wired, the 2 positives together and the 2 negatives together

[Bala]

What panels are they and what type of amp meter/rating.

[V8ater]

Kings 160w fixed solar panels. Rated to 8.79A output each

[Bala]

I have 2 160w panels from jaycar and no problems.

If you testing correctly and your amp meter is rated for minimum 20a I don't know why you are having a problem.

You shouldn't need to add diodes.

They are very cheap, perhaps one has a problem. Try contacting them to see if they have an answer.

[Mike90250]

if you have two, 5A panels and your battery is only asking for 3A charging, the 2 panels together will only provide 3A ( 1.5A each ) if you disconnect one, the remaining panel will supply all the power to the battery .

If the same result happens with each panel, you don't have a problem. Try putting a heavy load on the batteries/inverter, and test at noon. I think you will see individual panel outputs increase

[V8ater]

Interesting! Is that because it’s being run through a redarc bcdc? If I ran it straight to the battery would it bottleneck it? Like it has appeared to have done through redarc?

[Bala]

If you want to test panel output you do not have a charge controller or battery connected. You just connect the + and - leads of the panel together and use a clamp meter, or inline meter.

When you are running the panels through a charge controller to a battery the charge controller settings and the battery state of charge and condition dictate current coming from the panels.

[V8ater]

Update! I drained the battery by putting a large load on it and then then attached the solar panels, I saw about 15amps which suggests the redarc was only putting in what it needed! Thanks for straightening that out for me guys! Appreciate the knowledge

[turkynes89]

hello maybe i can help