Can I test Solar Panels without a charge Controller

[JK_Boston_Catalina310]

Hi Maine Sail,

I went ahead and purchased some Chinese knock-off semi-flexible solar panels (I know). I went with the Renogy from Amazon for $197.99 each and should have them next week.

My plan was to setup my system on a wood frame to do side-by-side testing of the two panels to make sure both are performing close to spec. I was going to put both panels on the frame, connect them individually by my Rouge controller and then connect the Rouge controller to a discharged battery with one multimeter in line on the positive lead to read current and one multimeter connected to the battery to read voltage. (I hope this setup sounds right for testing, I don't have a clamp multimeter.)

My problem came when I contacted Rouge because the MPT-3048 controller is listed as temporarily out of stock. They told me it would be 3-4 months before they had them back in stock. I really like this controller from my review of this and several others and I don't have a problem with waiting for controller because we aren't cutting the lines until October. But I don't have that long to send back the panels if they aren't performing.

Will setting up my test without the charge controller bias my results in anyway that I am not anticipating?

I may put too high of a current into the battery but it would only be for a short time to verify that the panel was working. The battery I would be using is a extra group 24 and not part of my current banks. I was originally planning to run the test for about 1 hour but was thinking of shortening it to 15-30 minutes due to the lack of the controller. If I cooked the battery I wouldn't really care because I was planning on scrapping it this spring anyways. I mainly kept it around to avoid a core charge for a buddy.

Sorry for the long winded question.

Thanks,

Jesse
s/v Smitty

 

[Maine Sail]

Just discharge the battery to 40-50% SOC.

First test open circuit voltage of the panels with them not connected. They should be near identical.

For testing current insert your DVM on the common post of a cheap A/B type switch that can handle 10A or so. Wire one panels + to A and the other + to B. Wire both panel neg wires direct to the load.. Now toggle between panels into the load. Output should be near identical

 

[Brian D]

You can get an inexpensive controller until the good unit comes. At least you will be able to use the panels without too much worry. Well, at least that is what I would. This also means I have a spare controller for emergencies.

 

[gettinthere]

I just received 2 of the 100w renogy panels.
I did the open circuit test and they were within .02 volts.
Is the test under load important vs open circuit test?

 

[JK_Boston_Catalina310]

Just discharge the battery to 40-50% SOC. First test open circuit voltage of the panels with them not connected. They should be near identical. For testing current insert your DVM on the common post of a cheap A/B type switch that can handle 10A or so. Wire one panels + to A and the other + to B. Wire both panel neg wires direct to the load.. Now toggle between panels into the load. Output should be near identical

Thanks