Hello, I’ve installed and networked 3 SmartSolar MPPT 100/2 charge controllers in our motorhome. 2 are for the panels on the roof and one is for the portable panels. I’ve now discovered that they cut out at a total output of 20Ah, but surely each one should be able to deliver 20Ah???!!
Am I getting this wrong??
What should I change?
I’m curious to hear your thoughts.
Willi
What is the power output of your modules?
And how are they oriented? Full power is less common now in October.
Hello, I’d like to try to explain the problem.
When I measure each circuit individually, each one gives about 10 Ah. Each circuit has a solar charge controller, and they’re all connected to a busbar.
When I connect 2 circuits, it charges at about 20 Ah.
When the 3rd circuit is connected, it should be 30 Ah, but it isn’t — it stays at 20 Ah.
The controllers then regulate themselves down so that the battery is only charged at 20 Ah!!
The battery isn’t full, of course, and the sun is still shining.
So, I hope everything is clear now.
Willi
How is your system set up in detail?
Please use the units correctly! Ah is commonly understood to mean battery capacity; PV charge controllers, for example, supply a charging current of 50 A.
I’ve added a sketch.
I hope this is okay.
If you have a BMS, is it limited to 20A?
Hi, without a BMS, it could be that one controller throttles back earlier because of the charging voltage — you should set it to the same value on all of them.
I’d try swapping them around at random. If it stays at 2/3 of the system’s output, it could also be that the battery has an internal limiter. If there’s a Bluetooth interface on the battery, there may be something you can adjust there too.
But yes, if the MPPTs feed into the +/- busbar, it should be fine as long as the PV modules are oriented similarly.
Unfortunately, I only have 2 MPPTs, so I can’t reproduce this. I do have a BMS, though — via Pylontech.
If necessary, connect the individual strings in parallel at the MPPT input. CAUTION: Be sure not to overload the MPPT, of course.
A BMS is installed, of course.
The charging limit is set to 100 A.
You can’t connect them all to a single controller.
hello,
there are several reasons why an MPPT is curtailed:
these values can be set centrally when devices are networked or a GX device is used!
so you should first check how the device that controls the others is configured. I can’t tell you how this works with Bluetooth networking. If a GX device is installed, you can configure it there; these are the DVCC settings. The lower of the values set by the BMS or DVCC is always used.
bye
Hi, I can’t see any connection in the picture, or am I reading the picture/sketch wrong?
Charging voltage.
But maybe link the charge controllers. Just an idea.
Set the float voltage on all the controllers to the same value as the absorption voltage and test again.
Some controllers switch straight to float charging if the battery voltage is already above that when they’re switched on.
