Is a micro inverter a 'off-grid'?

They are not "off grid" micro inverters. They are regular micro inverters, connected to his off grid Garage. His system can AC couple. If I can do it, you can do it. What does it means "AC Coupling" exactly and what solution are exits?

Does Antigua and Barbuda have a voltage converter?

In Antigua and Barbuda the standard voltage is 230 V and the frequency is 60 Hz. You can't use your electric appliances in Antigua and Barbuda without a voltage converter, because the standard voltage in Antigua and Barbuda (230 V) is higher than in the United States of America (120 V). You can seriously damage your appliances.

Can I use a microinverter to supplement an off-grid system?

You can easily use microinverters to supplement an off-grid system. If you are connecting it to an AC coupling capable system. I have a cheap 300W gti plugged into mine. Just wanted to see if it works. Also means I'm running AC thru 30m of cable instead of DC. Less voltage drop and simplifies the wiring.

How do micro inverters work?

Micro inverters are designed for grid-tied. They just produce all that they can and force it into what they are connected to. They expect to be connected to an infinitely available place to push their power. When not connected to the grid. They must be connected to something that can control their output (AC coupling). On a boat usually.

Can a hybrid inverter be combined with RSS?

Most hybrid inverters have ample capacity for most systems ( like most things nothing is one size fits all ), so just adding panels with RSS is the best option. If I can do it, you can do it. The main reason for AC coupling is to use an existing grid-tied system for a new off grid setup.

How much does a NEC 2020 module cost vs a micro inverter?

Once you are in NEC2020, its module level required shutdown, then the math is different as something has to be there, but even in this case its $30 rss only module vs $165+ for micro inverters, so more than 10 panels, string configuration still wins.