Solar panel reverse polarity question?

[RCtime]

Hi all
I accidently hooked my 9W Colman cl600 solar panel backwards for about 3-4 seconds before I realized my mistake.
I didn't have the means to test its out put and failed to remember to climb the rear ladder to see if the output diode on the panel was lit before I left it in storage.
I wont be back for a week or more.
Do these small solar panels usually have reverse polarity protection?
Thanks

[wa8yxm]

Well... A reverse polarity diode won't help you here. Here is way.

Normally current flows out of the NEGATIVE side of the panel into the NEGATIVE side of the battery, (This is the reverse of what happens in the battery when you turn a light on).

When you hooked the panel up backwards, What it saw was a "Super short circuit", a fuse, may have protected it, but the direction of current flow would have been NORMAL for the panel.. Just very very high.. odds of damage to the panel is likewise very very high.. But not, quite, 100%.

The only way to be sure is to stick a meter on it and see how it is performing. You can get decent digital multi-meters from harbor Freight for less than lunch at McDonalds now days.

[RCtime]

Thanks Wa8yxm

I took the time to go check the motorhome today and it appears all is well. (actually my wife wanted her cookbook she left in it)

Here is my set up. The standard 10W solar charger that Winnebago installed from the factory. Plus the 9W portable that I put on the roof in the winter months, total 19W. A tril L start.
When I 1st put the 9W on the roof my panel read 12.6 house batteries and 12.4 Chassis batteries.
I turned on the battery disconnect switch and the house batteries flashed 14.1-13.8 and settled on 12.8 and my chassis batteries had risen to 12.6.
With those great numbers I knew the panels were doing their job and I didnt bother getting the ladder extensension out of the compartment and climbing on the roof to check the charge diode on the panel or disconnect the panel to check its output.
I'll check it again in a week or so and I expect the chassis batteries to be up a point or two if this sunshine continues.
I am maintaining 3 - 12V house batteries and 2 - 12V chassis batteries.
Not trying to charge them, just trying to maintain fully charged batteries while in storage.

[wa8yxm]

I would still put an ammeter in line with those panels, Just to be sure.. It may be you damaged only one of them.. Or it may have survived, a lot depends on factors that are too diverse to go into here,,,, Like the wire size, and even the design of the panel.

[RCtime]

For sure.

The rating on this panel is 600mA, 15V (9W).

What could I expect to see on my multi meter if this panel was partially damaged.

Before I would get a reading in V when I put my meter on it.
But thats all I ever checked was the output voltage.

Your explaination of how the panel worked was excellent and even I could understand it.

[RCtime]

Checked the output on the cl600 9W panel facing directly into bright sunshine.
I had a reading of 20.2V. I didnt think these little things put out that much over their rating.

Colmann cl600 600mA 15V 9W

This was about 11:30 am. The house batteries were at 12.7 and chassis at 12.5

If I had taken the check later in the afternoon I suspect the batteries would have been up a point.

The triklstart was on maintenance, and not on charge.

[RCtime]

OK I guess my panel is shot. My meter shows .38 milliamps. My test leads were at 10A and com. is that 380?
Anyway it was in bright sunshine and it is rated at 600 mA
Voltage at time was 21.3

I like the looks of the Battery tender 10W and a 15W solar with the built in regulators.
Which one?

[leadman]

If the batteries are charged there will be almost no demand on the panels. Turn on some lights or fans and then take a reading.

[wa8yxm]

Quote:

Originally Posted by RCtime OK I guess my panel is shot. My meter shows .38 milliamps. My test leads were at 10A and com. is that 380? Anyway it was in bright sunshine and it is rated at 600 mA Voltage at time was 21.3

Those numbers do NOT indicate that your panels are toast.. in fact they are very good. Common wisdom is to expect 1/2 the rated output of the panel inless by "Bright sunlight" you are talking high noon, in southern AZ on a cloudless day and even then I'd not expect them to hit max.

If you want more info on this.. The place to be is Quartsite AZ (I did mention Southern AZ) and the two weeks to be there are the last half of January...... Now.. parking is kind of a premium that time of year. but there are several solar experts, both sellers and customers. All over.

You go there now and.. Well.. The old joke punch line "It's the only place where I have been that I can watch my dog run away from home.... For 3 days" applies.

But the last half of Jan, it's wall to wall RV