Regarding your Victron 75/15 MPPT solar controllers, the LED’s will change pattern over time:
The yellow light:
- OFF means low voltage from the panel (shade, darkness, cloudy)
- BLINK FAST means bulk charging (battery is low)
- BLINK SLOW means absorption charging (battery at 80% or so)
- ON means float charge (battery is full)
The green light (maybe it appears blue?):
- This LED is of no information in your installation. It indicates whether or not the “LOAD” output terminals are currently energized. You’ll notice on each controller that there are two terminals marked “LOAD”, but they are not connected to anything, so the state indicated by this LED doesn’t matter.
The only thing to keep an eye on is the yellow LED’s which will change pattern over time. There should be some sort of yellow activity, when the sun is shining. Look careful though, the yellow can be hard to see when its blinking.