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9 testing controllers:


When my new 80 amp Tracer arrived, I decided to do a little testing to observe how the controller did its
MPP tracking. I brought in an 8AH battery and connected it to the battery port on the controller and also to
an electronic load. The panel port was connected to a variable power supply. Both supply and load's displays
indicate current and calculate watts, which is very handy for testing.

I set the load to 5 amps and turned it on, then set the power supply at 30 volts and 5 amps. The controller
PV indicator turned on and it started drawing power from the supply. The draw was slow at first, only a few
watts, but after about 10 seconds it rapidly increased, up to about 75w. It took a minute to bring the
battery back up from the initial draw, but stabilized around 75 watts off the power supply and 68 watts into
the load.

I then tried varying the load and the voltage. Not much happened when the load was varied - the controller
did increase power supply draw a bit but it was a gradual adjustment. But whenever I changed the voltage on
the power supply, the controller backed way down on the charge current, and waited for the voltage to stop
changing, before again making a short delay and then accelerating the draw back up. This is the MPP tracking
in action, and it worked equally well on all three of my Epever controllers. They did an excellent job in
keeping the power supply's current right around the preset current limit so long as there was enough draw from
the battery and load. If the supply was a solar panel, the voltage would crash as the controller passed the
Impp on the panels. Due to the current foldback on the supply, it will behave somewhat similar when the set
current limit is reached, so it makes a slightly different but acceptable substitute for a solar panel.

I'll be testing some of my smaller controllers later to see how they behave. I have a CPY that's MPPT which
I'm expecting similar performance from, but the rest of them are probably not going to behave as smartly since
they're just cheap PWM controllers that probably don't do any significant power tracking.

I also need to test the boost function of the controllers, to see which ones support panel boosting. The best
way to do this will be to connect a 24v battery and dial the panels down to more like 16 volts. My usual
solar panel configuration will probably never need to boost, but I'd still like to know their capabilities.
(of course I can only do this with controllers that can support 24v batteries)




last updated 11/30/2023 at 20:12:34