>These are not terms commonly used in the industry, thanks for the clarification.

It's such an industry term that it's literally a named feature on multimeters.

>The 18k provides 65A for a few seconds as an example.

Yes, you'll see I gave you that spec in the opening comment. It's not a good spec for a whole home hybrid inverter.

>the 18k can push 50A on each leg and most residential are sized at 150a or 200A

That's not how you read a spec sheet for 240v device. A home service is 200 amp, at 240v. That's 48kw potential. 12k is 12k regardless of whether that's (120v * 50a) + (120v * 50a) or (240v * 50a). The legs aren't cumulative. You're implying the standing load capacity is somehow higher than its inrush capacity. It would need to be a 24kw (on the ac side, all of the janky chinese rebrand inverters all list their DC input to try to make themselves seem bigger) inverter to do what you're implying.

(50a * 120v) + (50a * 120v) = 12kw

A small home with a smaller 150 amp service is (150a * 240v), 36kw.

Edit: screw it, I'll address this as well -

>There is no reason to have a "pipe" so large that it only is used for less than 5% of the overall runtime. This is why the powerwall setup doesnt make any sense.

There sure is! The whole point is to offset usage. 50 amp standing load capacity means you can only ever offset 50 amps of usage at one time. Sure, most homes don't hold anything higher than that for long but I've seen plenty of homes hold over 20kw for a bit if they have pool pumps, well pumps, pool heaters, or any number of things going on. Any time the home draws more than 12kw instantaneously you'd be getting charged peak rates, which could be avoided with a larger standing load capacity. In addition, if you're in a municipality with a 'demand' rate you could enter in to a different billing rate any time you go over a certain amperage, meaning that ability to offset more of that in that instance, even just for an inrush, could make an even larger difference on your bill.

Look man, I run an $800 chinese inverter, and my batteries are MuRatas I harvested from decommissioned Sonnen cabinets that I rewired with chinese BMSes. The Powerwall 3 is a really good product and the pricing is great compared to comparable non-diy consumer grade products. The EG4 is not a good comparison point because it has nowhere near the spec or capability. You would need 3 EG4 18ks to have the inrush capability of a single Powerwall 3. Battery capacity (volume) is not the sole determining factor in value. This isn't even relevant but just as an aside, the EG4 isn't even a good value for the DIY scene, and has functionally the same support as rebranded drop shipped Chinese inverters.