Q: Bypass charge controller?

So I'm all set to fire up my new system, but the display on my MX60 is not working, and I'm waiting for the replacement unit in the mail.

And boy am I impatient; given the holiday and the distance to Hawaii, it'll be middle of next week at the earliest.

Meanwhile -- any harm done wiring 72-volt arrays directly into the 48-volt battery bank?

Given that:
- one can short-circuit panels without harming them;
- the voltage will drop to that of the batteries until they're charged up;
- nothing is being driven off of DC power, except the inverter;
- I'll be monitoring the battery voltage to prevent overcharge.

Battery bank is 24 L16s; panels are 9 Kyocera 175-watt.

- Ted


  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: Q: Bypass charge controller?

    Yes, you can direct connect .. no technical issues at all.

    You must be the charge controller ... so disconnect when the batterys are full ( you can only do Bulk charging ) and disconnect at night to prevent the panels from draining the batterys.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,500 admin
    Re: Q: Bypass charge controller?

    And you have to be very careful in disconnecting if done under load. DC can sustain some pretty good arcs. You should use a switch rated for the load and make sure that it is not near the batteries (hydrogen gas).

    You could also do a little "diversion loading"--Electric heater on the inverter to draw power roughly equal to the panel wattage...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset