Outback Flexmax 80 internal shunt?

alpineJeff Registered Users Posts: 1
Hello, I bought an off-grid home in N. CO at 8,000 feet equipped with 1x Outback Flexmax 80, and 2x FXR inverters set for 48V along with a dog's breakfast of panels wired into a combiner box. The panels range from 160 - 190W. We have a Generac 11kw generator.

We left the residence for what we thought would be a few days - turned out to be closer to a couple months. We didn't shutdown the house (novices we be).

The Outback equipment is from 2003 = 2004. Kinda long in the tooth. The seller originally used Lead Acid batteries, but was gracious enough to purchase the neophyte owners an 11kwh BigBattery which has been beeping since the day we walked into the home.

While we were gone, the stepper motor that controls the generator's run speed got stuck and kept throwing Overspeed errors, and shutting down. So I had the stepper replaced and the generator appears to be running fine. My sense is that this failure was the cause of all the other failures now occurring.

After the generator was fixed, the BigBattery would throw it's 200 amp (I think) breaker at least once a day, but often more frequently and each time, everything would shut down.

Not sure when in the sequence of events, but we lost one of the FXR inverters, causing the 220x 2-phase (reason for 2x inverters) to die. We're off grid loosing one inverter means no well pump. 

With 14 panels, and six 10amp breakers, clearly some of the panels are in series - the wiring is simply a mess. When all of the breakers are off, the panels, on the various breakers, read a combined voltage of about 85 volts. But the moment I turn on any of the 6 combiner breakers, the voltage drops to zero and the Flexmax 80, which was working, just stays in Zzzzz... or sleep mode. 

There is also, down stream of the combiner breakers, one breaker labeled PV. With that off, I can turn on all 6 breakers on the combiner with no shunting of the pv voltages. 

I have a new Flexmax 80 and Inverter, but wanted to reach out to the community to see if there may be some other reason for the dead short. 

Has anyone experienced a similar pv short? I'd kinda like to know what's going on before throwing new components into the mix.

In advance, thanks for your time and insights.



  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Lower quality breakers  ( AC or DC ) loose calibration when tripped and will trip at lower and lower amps with each activation, Manual or Overload.
    Get some of the switch duty rated  breakers ( tested by Midnight solar ) and sold at NAWS ( this forums host )
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Hi Jeff,

    Am a bit late to this discussion,   but;

    Generally, when an MPPT Charge Controller, like the FM-80 reads 0.0 volts on its input, it means that the power FETs (these are transistors that function to transfer power from the PVs into the battery), have been shorted by an accidental shorting of the positive PV input terminal and the PV, or battery negative.  OR, perhaps by a near-by lightning strike.

    IMO, Good Luck,  Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.