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Solar Panel Drawing Amps indead of Adding Amps???

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Solar Panel Drawing Amps indead of Adding Amps???

Posted 01 Feb '20 02:13 PM

Hello all,

I have an off grid powered house powered by 6 x 12v batteries all hooked up in parallel. I also have 4 x 150w 12v solar panels all hooked up in parallel too. Things were good however I decided to move up to 24v. I rewired the batteries so that they were now in three pairs so they were 24v. I did the same with the solar panels, putting them into two pairs so they were also 24v.

My mppt can switch between 12 and 24v with auto detection.

Hooked it all up and everything worked.

Happy days.

HOWEVER

I recently bought a new 290w 24v solar panel and added it to my array. The others being functionally 24v and this one being 24v I thought there would be no issues. So I hooked it up and was surprised to see no increase in power. Checked all of the connections and they were fine. I even removed the other panels to just have this one running and still no amps would flow (confirmed this with fluke clamp metre). Checked the volts and it was as expected approximately 30v. I connected just the original panels up and everything was fine, around 15 amps. However as soon as I attached the new panel it dropped down to about 9 amps as if the panel was drawing amps instead of adding them.
I contacted the supplier and they sent out a replacement panel. However after hook it up today I am having the same issues. The amount of amps going to my mppt DROPS when ever I add the new panel to the array.

Any help would be much appreciated as I am very confused at this stage.

Thanks!

RE: Solar Panel Drawing Amps indead of Adding Amps???

Posted 02 Feb '20 07:20 PM

Isolate your new panel from the system, put the clamp meter on its leads and short them together in full sun, you should get a current reading near the panels rating. Open the short and measure the voltage, again should be approx the no load spec for the panel. I would expect around 38 volts unloaded. The OC. voltage should be similar to the other panels for your Mppt controller to work with all in parallel, if the new panel has a substantially higher voltage then the controller maybe locking on to that and ignoring the old panels or vice versa if lower.

Cheers
Mike

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