Do off grid inverters neutrals carry only the unbalanced load?

BB. said:

In general, yes the L1-L2=N current will work OK. In theory, you could run into issues if the L1 rooms were running Motors/Old Computer power/etc. supplies with poor power factor, and the L2 rooms were running new computers and hair dryers. The poor power factor loads would not cancel (part of) the good power factor loads. But I would not expect any such issues.

https://www.amazon.com/s?k=AC+Amp*Hour+Watt*Hour+meters&ref=nb_sb_noss (general AC power meters)
https://www.amazon.com/CrocSee-CRS-022B-Frequency-Multimeter-Transformer/dp/B07K3S4K9L (example of a nice meter?)

With a cost of $15-$20 per meter... If these are guess rooms for "random" visitors that stay a few days/weeks (vs 6+ month volunteers/workers) that you cannot really "train" and monitor--I would think that installing a bank of 12 of these meters at $240 (or more--office? Another for "Mains" power... Or just get a pair for L1/L2 mains power--And if things don't look right--Go knock on doors) and a metal "break out" electrical box to hold all the current transformers/monitors) would let you keep an eye on the system would let you watch for folks that use extra power (such as a hair dryer) or leave stuff on (laptop, lights, etc.) and drain the system--Without having to go into each room and check.

Other ideas may be to use timers or motion detectors for room lights, perhaps even outlets (timer) to "remind" guests that power is not unlimited here.

https://www.amazon.com/s?k=ac+timer+wall+swtich&ref=nb_sb_noss

"Motion detectors" and timers that turned off the lights every 30 minutes "after work" were hated for lights at several companies I worked at... Engineers who came in late / worked "late" were plunged into dark every 1/2 hour (and many of the emergency/night lights had failed over the years--So there was little ambient light until people tripped over stuff until they could get to the local light switch to turn lights on again... Was a big mess (people use coffee stirrers to hold switches on--burned out relays that were designed for just a push on, engineers came late, left "on time", had to fix emergency lights, etc.).

If you do the automated lights--I would think some sort of room night light (low power LED) would be nice (and not draw much power). Either a light switch with nightlight, or a plugin night light...

Probably 90% of the time, you will not have issues--But those few times when one or two people don't follow the program, it could save you a night without lights/power, or a dead battery bank.

-Bill

BB. said:

As Michael says--Besides the AL "grease", you may also want to look at AU/CU compression connections/Compression-Crimping tool (such as used by our local utilities for connecting AL pole drop to CU building wiring). They are rated for both AL/CU and weather tight.

Just use one end for AL, and bring some CU pigtails for transition to CU building wiring (generally, compression connectors have a relatively small range of acceptable AWG/Diameter wiring... You may need to use a "heavy" CU AWG cable for compression connector, and then transition to smaller AWG copper building wiring (with locally available splicing connectors).

In addition to kWH meter(s) for genset--You might want to look into some sort of fuel totalizers too... We see smaller AC gas/petrol gensets get something like 3-5+ kWH per gallon of fuel (diesel should be more efficient)... You can keep track of genst/battery/power usage and watch for anyone that is "out of the typical range" (using 10 kWatt genset run  tens/hundred watts of lighting, somebody siphoning fuel from tanks, short fill, etc.).

https://www.amazon.com/s?k=fuel+totalizer&ref=nb_sb_noss_2

I have not used a Fuel Totalizer--So I know even less than typical about them. 

Just using Amazon links for pointers... I have no opinion one way or the other about the product(s).

It sounds like you know a lot more about this stuff than I. 

Let us know how it all works out (the good and the bad).

Take care,
-Bill

Dave Angelini said:

Schneider XWP would be my choice for Inverters. I have yet to find one that is at good at a wide range of Offgrid Issues and has the high voltage charge controllers that make easy installation and easy to expand later. The Insight local and cloud monitoring is as good as it gets.

The mini-splits are 240vac right? You can buy  4/0 to #2 bus screw connectors from Midnite or a good hardware store. Tape them and install in a JB.  Are you shipping to Haiti or ?  Good Luck !