Turn off solar panels???

msgiesermsgieser Registered Users Posts: 24 ✭✭

I have a new solar install that is working great, but I have a question. I have 3 - 280 watt panels feeding thru an Outback combiner box (each panel on it's own breaker) and then into a Morningstar Tristar MPPT-60 charge controller. The battery bank is 4 - Trojan T105 RE'S for 450 ah's at 12 volts. I can run the battery bank down to 70% at night and on a sunny day, the panels have the bank back to 100% by 10:00am plus running a few other loads. So far, looks like I have plenty of panel vs batteries and everything is working as designed.

Now the question. This is a small, off grid cabin. I use it for 5-7 days once a month, then it sits unused for 3 weeks. Should I shut down the solar panels while I'm gone (or turn off the breakers to two of the three panels) or just leave everything at full power and let the charge controller handle everything? Or, should I leave a few smaller loads on and let the inverter power them to use some of the battery capacity daily. Now, I turn off the inverter and throw the disconnect from the batteries to the inverter. Is it acceptable to flip the circuit breakers off when the panels are under load? Thanks for your answers!


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Turn off solar panels???

    Shut off or disconnect all loads, including the inverter.

    Leave the charge controller and panels connected. Make sure the batteries have proper water level before you go and they will be fine.
  • BB.BB. Super Moderators, Administrators Posts: 28,315 admin
    Re: Turn off solar panels???

    Also check the float voltage (and timer--if applicable) against the Mfg. recommendations.

    Overcharging the batteries is kind of hard on them too.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • VicVic Solar Expert Posts: 2,938 ✭✭✭✭
    Re: Turn off solar panels???

    Hi msg,

    Personally, think that it is best to switch DC breakers (really, any breaker) without load current flowing, if at all possible. Many Charge Controllers have a rest/off/sleep/disable function that removes the load current twix the PV in and the CC.

    For the inverter breaker, if the AC loads are small, and the CC is sleeping, then it is prob OK to use the Inverter breaker as a switch. There is still the question; will these breakers to endure the mechanical cycling as switches? This cycle-life data is often difficult to get from the manufacturers of the devices. JMHO, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
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