PCM60X Extra Panels?

I have a PCM60X charge controller. It is rated for 3200w when using a 48V battery system. The max charge current is 60A. It has a charge current setting you can change if you want it less than that, but my is set to the max of 60A. Is it okay to connect panels which have a total rated output of 3840w to the controller? The way I see it, it's not going to charge above 60A anyway so if it reaches 60A, it's just going to waste/not use the remaining energy on the PV side.

Or is this generally a bad idea?

Thanks.

From the manual of my TS-MPPT-60:To comply with the National Electric Code (NEC), the current rating of the
controller for solar charging must be equal or greater than 125% of the solar
arrays short circuit current output (Isc). Therefore, the maximum allowable
solar array input to the TriStar controller for compliance with the NEC is:
TS-45: 36 amps Isc
TS-60: 48 amps Isc

Check the manual.

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In other words, the charge controller is rated for a certain input current. The margin is a cushion for possible peaks, e.g. due to temperature coefficients. Exceeding the limit is not advised.

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According to a quick search, the PCM60X is MPPT. If your array is under the maximum array voltage for the PCM60X, you could increase the series strings to reduce the current.

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Oops! The quote was actually from the PWM version. The point remains.

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I looked at the manual. There is max of 3200W input for a 48V system. A possible alternative, if you need more output for charging, is to puta second controller in parallel and split up the array. Check the manual about parallel controllers.

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Chapter 6 in the manual.

No worries to go to 4kw on that controller. It will limit in software. But if you want to pull max out of it its always better with 2 devices. Then you get some redundancy as well,

The max is generally a max that it will be able to put through it. As long as max voltage keeps below the max rated you are fine. That's the beauty with MPPT.

I have not heard of any MPPT controller dying because of more panels hooked up to it. As long as it will be able to set max current going through.

Remember you can always count on losses and inefficiencies. The direction, the temperature, the distance from the controller, the weather. All these things will creat losses. If you had 4kw of panels you will never achieve that output.

daromer said:

No worries to go to 4kw on that controller. It will limit in software. But if you want to pull max out of it its always better with 2 devices. Then you get some redundancy as well,

The max is generally a max that it will be able to put through it. As long as max voltage keeps below the max rated you are fine. That's the beauty with MPPT.

I have not heard of any MPPT controller dying because of more panels hooked up to it. As long as it will be able to set max current going through.

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You're right. I neglected to do the math. 3200W would be about 60A charging currentat 48V nominal battery voltage. As long as he keeps the Isc under 48A and Voc (oc?) under 145V.

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4000W/48A=83V strings of 3 24V GT panels would fit.

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That might be Vmp. The manual isn't clear - at least where I found maximum input voltage.

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And of course, if that is actual input voltage, the panel voltage should be derated for thetemperature coefficient .

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Just trying to be thorough.

Around my area its common to add 20% extra panels just to make sure you get as much as possible out of the equipment. Yes during full summer days you will hit the max limit but the software in the controller will limit the current output and therefore no issues. Voltage on input will of course rise but that's no problem either since you should have set the system up based on those before hand.

daromer said:

Around my area its common to add 20% extra panels just to make sure you get as much as possible out of the equipment. Yes during full summer days you will hit the max limit but the software in the controller will limit the current output and therefore no issues. Voltage on input will of course rise but that's no problem either since you should have set the system up based on those before hand.

Click to expand...

That makes sense. It gives you an edge before and after full sun and on cloudy days.