Comparing inverters in parallel vs splitting into multiple systems

ABarbarian

New Member
Joined
Mar 13, 2022
Messages
20
I am planning on purchasing an off-grid system, and then increasing it's capacity in a year or so. My plan is to buy one set now, then a second set including inverter/panels/batteries later.

I am currently considering whether to hook the second set into the first set with the inverters in parallel vs having each set managing it's own MCB/loads, I see good and bad in both options and wondered what others thought.

I would also have non-critical loads powered by the grid to reduce the needed size of the solar systems.

If splitting into different loads my idea was to have cables going from eg each outlet plug in each room to eg 3 MCB's, one for each solar system and one for grid, I would monitor the load usage on each solar system and could re-wire anytime I wanted to adjust loads on each system. I could also have switches and wiring that would allow me to switch each inverters load to the other inverter, I would probably also set each inverter to use grid as backup (not so important in this topic).

I feel the benefits of running inverters in parallel are:
- simpler wiring
- more efficient use of available power, all loads will pull from whichever battery/solar set that has available charge

Benefits of separate systems is mainly isolation, eg:
- Any failing in one set is isolated from the other set
- The components for each set would be purchased at separate times, there might be a mismatch somewhere
- Maybe a little more efficient as no merging/syncing of the inverters? Might be negligible
- Allows me to buy different inverter brands in each set to test out which I like better

For example we get a lot of lightning here, there might be a reduced chance of both inverters frying if they are separated (although if connected to grid as backup there is the chance the charge could pass that way?)

Appreciate anyone's thoughts.
 

Bossrox

Solar tinkerer
Joined
May 21, 2021
Messages
261
Location
Columbia, SC
If you want to stack inverters, you 1st need to find out if the brand you want will accommodate that & use only that brand. You can't have 2 different brands in parallel. Having 2 different inverters that don't have sync'd sine waves will result in destroying them.
 
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