Could use a little advice

[Zwy]

How would they share surplus and avoid inefficiency/lost production? Standard stacking of the inverters on same batteries?

Could be done but why do it if not needed? Was an energy audit performed?

There isn't enough battery there to run 2 houses. It will probably take at least twice that amount to run 2 houses minimum, probably more. If 2 separate systems and one has higher loads, move more battery reserve to that house.

Combining inverters at a central point can lead to much higher hardware and wiring cost. Everything gets up sized. Timing is another item, if most loads in each house are on at the same time such as around meals, then does combining inverter output at a central point make any sense? Currently each house is fed power thru the 100A breakers from what I see. If combining systems, then wiring will most likely need to be changed as two 18Kpv's can output more than 100A. It would be much less costly to leave the current 100A wiring to each house in place, install an 18Kpv at each house and wire the 100A circuit into the 18Kpv input. Wire and install is never cheap. Don't forget the conduit will need to be upsized too. This also avoids the 125% rule.

 

[zanydroid]

Interesting points. I was going by my knee jerk engineering principles (common resources have higher utilization efficiency at the expense of worse isolation and redundancy).

I’m still not sold on separate. I am assuming two inverters minimum in both separate and shared cases, and minimum capacity of batteries to match.

If the surge can be satisfied with one dedicated inverter per house, the exact same surge can be satisfied by two common inverters. And actually can handle a wider range of surge distributions.

The 18kpv can sit ahead of the two 100A breakers and those breakers retained. That would leave the wiring away from that point unchanged (the main expense). Then all wiring / subpanels / service equipment at this point is blasted away (likely needed anyway for separate systems unless you do it at each house).

Another consideration would be how much space etc there is at this central point vs each house.

 

[Bannsco]

This is the diagram that EG4 suggests.. is this a lil over kill for what I’m doing ?

 

[Zwy]

View attachment 192212

This is the diagram that EG4 suggests.. is this a lil over kill for what I’m doing ?

If you want full off grid capability with generator backup and 2 houses on the system with shared capability, it will be close to what they show. Filter Guy probably drew that and he is very good at putting systems together and the diagrams.

I'd run each house separate with it's own battery bank, 18Kpv and array. Combining 2 houses together leads to a much larger wire size and all components get costly as amps increase. I'd forget completely off grid until you think it is possible after the system is running. Every price a generator to run 2 houses? Use grid for backup. You can always use a cheap generator with a Chargeverter for generator backup down the road.

Sticker shock set in yet?

 

[robbob2112]

This is the diagram that EG4 suggests.. is this a lil over kill for what I’m doing ?

Probably easier if you rotate it and crop it for the rest of us... when I do it the file pixelates because the source isn't good.