MPPT charge controller behaving as PWM of late

[bhvm]

Hello everyone,
I have a small Off grid solar unit at home.
It consists of 2x 400W solar panels (40V rated at 5.3A, 44VOC)
I am using a small MPPT charge controller as below-

https://www.urjakart.com/systellar-20a-12-24v-mppt-solar-charge-controller.html

[Mike90250]

Generally, with MPPT chargers, as the batteries require less power, the charger reverts to PWM mode (both mine do) but if the battery voltage goes low, they then go to MPPT mode to harvest as much as possible,

[bhvm]

Generally, with MPPT chargers, as the batteries require less power, the charger reverts to PWM mode (both mine do) but if the battery voltage goes low, they then go to MPPT mode to harvest as much as possible,

This wasnt its behavour past 2 years. Even if batteries were fully charged, it would hold the panel voltage near 35~40V and trickle charge a few amps into battery (As low as 0.3A). So far I have'nt seen panel voltage above 15.5v this week.

[littleharbor]

Could there be a problem with your panels, or wiring to the controller? Never seen that particular controller before. I see the warranty is two years, hmmm....

[rwest]

Sounds like a problem with the controller. However, to rule out panel issues, I would disconnect both modules from each other and the controller and measure Voc to rule out bypass diodes or damaged internal wiring ( I doubt you will find anything). Second, I would connect only one module to the controller and see what it does. Then disconnect that one and connect only the other one, and again see what happens (with voltage and charging current and all that). If the two modules operate in an identical manner, then I would rule them out as the problem.

It sounds like the controller buck circuit failed and is shorting the battery to the modules. The controller doesn't seem to have any PWM setting so for it to operate this way might indicate failure. Manual for the controller is here: http://systellar.co.in/wp-content/up...r-2015-Web.pdf

Be safe!

[bhvm]

It sounds like the controller buck circuit failed and is shorting the battery to the modules. The controller doesn't seem to have any PWM setting so for it to operate this way might indicate failure. Manual for the controller is here: http://systellar.co.in/wp-content/up...r-2015-Web.pdf

Be safe!

Seems like this was it. The "MPPT" Part had failed. And Interestingly it reverted to PWM style Operation rather than Shutting down or Throwing up and error code. I had to send it to the Manufacturer and got it repaired for INR 1000. The performance is now back to regular levels.