Pros and Cons of connecting Inverter to Controller vs. Battery

d3faultd3fault Posts: 1Registered Users
I'm building my first off-grid 12v solar system and was surprised when my [MPPT] solar controller arrived and had connections for "load". I was under the impression that my inverter would be connected to the batteries, not the controller. After doing a bit of research I now think either way is possible (can someone please confirm this?), but I'm wondering what the differences of each configuration would be.

I guess most importantly: Will both configurations give power to load _before_ charging the battery?

I don't want to use my controller's "load" connection because the controller's current rating is only 40A. My [also MPPT] inverter is 1000W continuous, so if I _HAVE TO_ use the controller's "load" connection then that means I wasted money on too big of an inverter, since 40A x 12v = 480W, which is much less than 1000W :(.

Thanks in advance for your replies,


  • mcgivormcgivor Posts: 2,164Solar Expert ✭✭✭✭✭
    edited October 2017 #2
    Good thing you're observant, connect the inverter to the battery with a fuse or circuit breaker rated to protect the conductors between the two. The load terminals are only suitable for low current loads, some/most are rated at the amp capacity of the controller, but it's always best to connect to the battery, especially inverters. The one benifit of the load connections is the load will be disconnected at a certain voltage to prevent over discharge, so any DC loads such as lighting, is good to use the load terminals, the inverter should have low voltage disconnect, to protect itself, which in turn protects the battery. These values can be quite low, disconnecting when the battery is almost completely dead, it's better not to rely on these values on a regular basis by sizing the battery to support the anticipated loads, never dropping below 12V, or 50% depth-of-discharge, as a maximum.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

  • fratermusfratermus Posts: 22Registered Users ✭✭
    One could set the LVD to something sane and run loads off a relay/solonoid triggered by the LOAD output.  Works for me.
    2017 Promaster 159" DIY camper
    570W mono / 220AH GC
  • d3faultd3fault Posts: 1Registered Users
    thanks mcgivor! I wasn't going to put a fuse/circuit-breaker there either but I will now :)
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