Any way to identify a solar panel or match it for hookup in series?

[Ball]

Hi. I have a panel on a vehicle installed by a previous (and likely very stupid) owner. I would like to purchase another panel and hook it up in series with this one (using an MMPT controller). Unfortunately, the panel does not have a label (it probably came off). I was hoping someone could advise me how to match a panel to hook up in series if at all possible.

The panel also looks different than any other panel I've used. There are NO solder lines on the surface of the cells or visible anywhere. The cells are dark blue (almost purple) with a bit of texture to them like rubberized handles. The array is 12 x 6 cells and it's currently producing 38v under load with sunny, indirect light, charging the battery bank at 144W (13.4V, 8.5A). If anyone has seen a panel like this, or knows how to hook panels in series, please let me know. Thanks. -Ball

[Ball]

I should add that there are NO crystalline structures visible and I get more wattage on a good day. I suspect maybe a 160w panel? It's a good panel, but I need more.

[Ball]

61.5" x 31.5" using 5" cells

[Mike90250]

Sounds like an amorphous panel. They often had a pretty short lifetime. You might be better off with a pair of new ones.

To test it, there are 2 tests, and you need a multi-meter for both. These tests are both DC
Test 1 Open circuit voltage. Set meter to 200V range. Measure the voltage of the panel. You are looking for about 25V
Test 2 Short Circuit amps (current) Set meter to 10A range, you may need to move connections to the amps port on the meter. You need full bright noon time sun for this. You are expecting 5-10 amps from the panel.

final step. Return the meter connections to the voltage locations, then put the meter away. If you leave it at the amps connection, you will almost certainly fry the meter the next time you use it.

[Ball]

Unfortunately I can't point the panel at the sun (like I said, installer was an idiot).

I've seen amorphous cell panels and this in no way looks like one. All the amorphous cells I've seen are painted on glass. These are separate 5x5 cells mounted in a grid. Also, amorphous cells are so weak I don't see how I'd get 120w out of a panel this size in indirect winter light.

Not saying you're wrong, but I've never seen a panel like this.

[sensij]

It fits the description of the early X-series Sunpower panels... X19-245-BLK, or maybe X20-250-BLK. If you want to put another panel in series with it, you probably need to look for something with an Imp around 5.6-5.8 A.

[Ball]

I think you're onto something. This matches very well, at least without photos:

http://www.solardesigntool.com/components/module-panel-solar/Sunpower/2230/SPR-X20-245/specification-data-sheet.html

[Ball]

Thanks sensij, you're a genius. It looks like one of these

Screen Shot 2018-01-15 at 2.17.42 PM.png

Now, what specs do I look for in order to hook up another panel in series? Do I match ISC?

[littleharbor]

Sunpower had panels in the 205 - 220 watt range that fit your description.

Sunpower 225 3 (1).JPGSunpower 215 3.JPG Sunpower 225.JPG

[Ball]

Right, so when finding a panel to run in series with this model what stats matter?

[littleharbor]

Imp. The Amperage/current rating. The lowest current module in a string will dictate the string's current. If the module you add has slightly higher amperage output it will act like the other modules and the amperage output of the string will remain the same. If you add a slightly lower amperage module, the string amperage will be pulled down to that amperage.