Slave vfx3648 green light stops blinking

I have an outback solar system configured "outback series" 2 FX's connected to two 120/AC output legs that produce 240 VAC between them. Connected between the AC Output Legs is an X2-40 autotransformer. A Hub and Mate included. This type system can continuously power 4-7.2 KW although in my case it almost never does and only one inverter(master) is on and the other(slave) is in standby with a green light that was always blinking.

That blink indicator on the slave FX was in normal status for almost 3 years and this week when we finally got an unseasonal early heatwave 90's in our Ca mountain region for several days that started to make the slave invertor green light go solid green(no blink) for several hours.

This blinking light returns, I noticed in the late evening and is good for most of the next day, or until the air temperature goes above 80 degres F. What caused this to happen and is it a potential problem or sign of something ready to fail?

This slave invertor used to turn on normally with the solid green light indication for that moment when a load of about 1KW+ is drawn from some appliance such as a microwave or a power tool is used on occasion at our home.

It doesn't affect my power output and I know when it is on a nominal draw of power is being used. When that green light is on is it just a light malfunction or is is that invertor actually on that time period? How can I fix?


  • rplarryrplarry Solar Expert Posts: 203 ✭✭✭✭✭
    Re: Slave vfx3648 green light stops blinking

    My system is similar to yours, but I'm paralell stacked. The slave inverter blinks in the standby mode continuously until it senses a load of 10 amps or more on the master inverter. Thats according to the book, in reality it wakes up much more often than that. I live where it is HOT in the summer months (100+ almost everyday) and I have never noticed the slave coming on because of the heat.

    Possibly you could use the mate in the meter section and see what each inverter is producing power wise.

    Good luck with it,
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Slave vfx3648 green light stops blinking


    I agree with Larry that this sounds like "normal" operation.

    With the "OutBack Series" stack and the X-240 transformer, the "master" inverter normally provides all power for 120 VAC loads on L1, 120 VAC loads on L2 (via the X-240), and all 240 VAC loads. The "slave" inverter sleeps in a very low power mode (~3 W, IIRC), and the green LED blinks to indicate this state.

    When the output of the "master" inverter increases to ~12 A AC (~1.4 kW), it will signal the "slave" inverter to turn on and help with the load. The "slave's" green LED will then illuminate continuously. I believe that each inverter should be supplying the same amount of power when they are both operating. Uneven loads on L1 and L2 are balanced via the X-240.

    Figure 8 in this archived X-240 manual may help explain this latter point:

    When the total load on the two inverters drops back down to below ~4 A AC each (again, IIRC), the "master" will pick up the total AC load and signal the "slave" inverter to go back to sleep. The "slave's" green LED will than return to blink mode.

    HTH, and I hope you enjoy your system!

    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Slave vfx3648 green light stops blinking

    Thank you both for your response/advice. I have been away from home (that location) since posting and will check the mate reading when I return next week.

    Another related change or potential problem related to that slave invertor was a loud unusual cooling fan noise that came on when that slave inverter was in use during hot weather days. I have been noticing a fan rubbing noise for months since last summer/fall. It's not a clean air flow sound. That fan has since stopped altogether recently as far as I can tell when that solid light came on last week and when no power was drawn by that slave inverter. I will apply a load so both invertors come on during hot weather days and check again for light and fan response.

    This might be nothing but I just get concerned when something changes its' pattern after functioning in a consistant way for several years...kind of like a check engine light
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Slave vfx3648 green light stops blinking

    OK... Also, please let us know which model inverter you're using.

    Jim / crewzer
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