None of those things matter when your solar array is 4.5 kW and you have a standard 150A/200A grid in....

Like I said, they basically are not sold to scale like a normal household uses electricity.

EDIT: What the heck is in-rush and backfeed? Are you talking about AC input to charge the batteries? The 18k is 50A @ 240VAC (12kW) fyi. Also, why does the charge rate even matter there? For the AC output its also 12 kW...the family is average 48 kWh days, which is 2 kW hourly average...

Inrush is exactly what it says it is, it's inrush current. When you have a sudden surge on something, that's inrush. Lots of appliances in your home have a large inrush, much larger than the breaker they're on. Inrush happens faster than a breaker trips, which doesn't matter when you're on the grid and the inrush is lower than your mainbreaker, it matters when you have an inverter in the way with a passthrough limit and an inrush limit. Typical central HVAC units have LRA over 100 amps.

If we're talking about 'doesn't even matter with a 4kw array' well, hell, how the hell you gonna charge ~40kwh of battery with solar array that nominally produces 20kwh a day on its best day, assuming all conditions are perfect?

Backfeed is what the inverter can push out from the battery to the home. It's the size of the tube coming from the gallons of water reservoir. EG4 18k has a tiny tube, no matter how much battery you put on it. Like emptying a 50 gallon drum with a drinking straw(and with the 4kw array, filling it with a 12 oz cup).

> Inrush is exactly what it says it is, it's inrush current

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

> Lots of appliances in your home have a large inrush, much larger than the breaker they're on.

And inverters are designed to compensate for short term surges too fyi. The 18k provides 65A for a few seconds as an example.

> well, hell, how the hell you gonna charge ~40kwh of battery with solar array that nominally produces 20kwh a day on its best day, assuming all conditions are perfect?

Because you can't and don't need to...you should be asking the author of the original post, because they do what pretty much every other grid tied system which is that you pass through the power from the grid.

> Backfeed is what the inverter can push out from the battery to the home.

https://www.wartsila.com/encyclopedia/term/backfeeding huh?

> It's the size of the tube coming from the gallons of water reservoir. EG4 18k has a tiny tube, no matter how much battery you put on it.

1. The 18k can push 50A on each leg and most residential are sized at 150a or 200A, which are ridiculously oversized, so at most, even with two EVs and a 4 ton AC running in Texas, I max out at 150A. I can put 3 18k's in parallel if I really want to and its STILL cheaper than a powerwall battery/inverter combo.

2. 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.

>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.

> This isn't even relevant but just as an aside, the EG4 isn't even a good value for the DIY scene

I would respond to all of your items individually again but its clear by this comment I can't you seriously and now you're just trolling.

I'd love to know why you'd choose an EG4 18k (which is actually a 12k AC inverter, with a questionable track record on support and warranty) over a Sol-Ark 15k (which is actually a 15K AC inverter, and has tech support that responds) now that Sol-Ark dropped the price on 15ks to sub $5,000 MSRP.

I'd rather land wires in a Sol-Ark, it has better support, it has a higher AC output, it has a higher battery charge rate, and it's the same price.

Ok lol...so it turns out you're not even correct on a powerwall's spec...each inverter maxes out at 48A/240VAC...LMAO

Be gone troll.

https://energylibrary.tesla.com/docs/Public/EnergyStorage/Po...

Yes, 48 amps at 240 is 11.5kw. Each Powerwall 3 is 11.5kw(edit: not to be confused with its capacity which is 13.5 kwh, one is a power output, one is a storage capacity. Just so you don't go thinking that's some amazing mixup between the comments). The original comment is all within your framework of 3 Powerwalls vs one EG4 18K with 3 batteries. That's 12kw AC for the EG4, and 34.5kw on 3 Powerwalls. I've never stated a single powerwall has more output than that(hell I even rounded down on the output of the 3 powerwalls to 34kw), only that they have a very impressive inrush and solar capacity. The incongruity of the comparison between the two systems is the entire origin of this discussion. Do you even remember what you posted and I responded to? You don't know how to use an amp clamp and don't understand the American split phase power grid. Stop consulting ChatGPT for 'gotchas' and actually read what you're writing.

Just to be perfectly clear on your continued misunderstanding - each powerwall is also an inverter, it has its own AC power output. That stacks. The batteries strapped to the EG4 are all limited to going through the EG4. That means no increased output for adding more batteries. No stack.

With 3 EG4s in the comparison you would have a similar standing load capability(36kw claimed), however you'd still only have roughly 1/3rd the inrush capability(190 amps).

Honestly, I thought I started this conversation nicely enough and went out of my way to be informative and you've only tried to insult me and be snide while having the loosest grasp on the subject matter.

You keep throwing out specifications without understanding their real life installation use cases and then go as far as to make claims like "EG4 support is bad for DIY'r" which is so far from the truth it's hard to take anything you say seriously. There are hundreds of thousands of forums and YouTube videos from DIY who rave about EG4. In fact Sol-ark has a sketchy support track record (source - several installers I work with)

> The original comment is all within your framework of 3 Powerwalls vs one EG4 18K with 3 batteries. That's 12kw AC for the EG4, and 34.5kw on 3 Powerwalls.

And for the last time, you do not need 34.5kW continuous AC output for a house that is averaging 2 kW per hour per day. Yes, they have two EVs, but also these do not need to charge at their full potential if you plug them in every night. The author isn't generating enough energy from solar of their battery bank so it's pulling from the grid anyway for those loads, so a grid bypass (which EG4 supports up to 200A) means you don't need the inverter to pump out 34.5 kW to loads anyway.

The thing you keep glossing over is that the fundamental problem with a powerwall for scaling systems is that each battery bank you purchase requires you to purchase a built in inverter. The same nearly identical system from EG4 is an 18k + 15 kWh battery which costs $8k, and powerwalls cost $12k+. Thats a 50% premium to get you 185 LRA but 8 kWh less capacity. For an extra $250 you get an AC soft start and a 185 LRA is completed unnecessary and irrelevant.

> Yes, 48 amps at 240 is 11.5kw.

You keep saying these things like I don't understand the math.

> You don't know how to use an amp clamp and don't understand the American split phase power grid.

Lol. And you don't even understand that specifications ratings because they very explicitly say the amps at VAC ratings (120/240) because while it's entirely possible to reach the full potential of wattage... in real life, it's unlikely you will due to how split phase works with inverters. Inverters are rated by amps per leg because your loads on one 120v leg could be higher than the other one (unless all of your loads are 240v in which you would always be using the same amps on both legs).

So to conclude:

1. An identical system is $53k (Powerwall) versus $31k (EG4), which is still hilariously overpriced.

The only measurable differences are:

EG4 gets 6 more continuous AC amps (up to 1.44 kW more)

Powerwall gets much higher surge capacity (555A vs 195A)

EG4 gets 8 kWh more capacity

2. If you need more than 195A surge, you put a soft start in or just let the inverter bypass temporarily to grid.

3. You would never size this system with 3 inverters for someone averaging 48 kWh/day, so the author spent £7k on an additional battery and got an unnecessary inverter purchase which is now directly eating into his ROI.

>You keep throwing out specifications... >And for the last time...

Well, neither of these are relevant to my original comment. I never commented on the value prop of the original install, only that your comparison in pricing is just not accurate as one is much more capable. Yes, lots of people want 34kw of standing load, because they want to ensure the offset of their HVAC unit. Generally people getting these systems have ridiculous homes, I've worked on a home with 3 20kw diesel generators. I've worked on a home with a seperate 200 amp service just for their pool side projector TV. Just because someone's wants aren't reasonable doesn't mean they don't want it.

>There are hundreds of thousands of forums and YouTube videos from DIY who rave about EG4.

EG4 sucks to try to pry anything out of. I don't actually like Sol-Ark that much either, but they're better to deal with and a better deal. Best deal is just to get an SRNE or similar straight from the source. Again, I paid $800 for my SRNE. I could get a second and parallel it and be outperforming the EG4 for a $3,400 discount. Youtubers are youtubers, not a source of truth. All those same youtubers shill battle born, too...

>Lol. And you don't even understand that specifications ratings because they very explicitly say the amps...

I'm not the one that has conflated two 50 amp phases with a 100 amp service. That's a 50 amp service. 12kw is 12kw. I keep repeating the math because you clearly keep misunderstanding it. A small electric range is typically on a 240 50 amp circuit, incredibly common in most households, and that's a small one.

>Identical system.

How is this identical? $5K for all other labor and materials? How much you paying per foot for the Class K to parallel the batteries? What's the homerun distance on the PV? Your AHJ require metal conduit on the DC runs inside the attic? Shit, if they require a 3R lockable lever disco that's $900 right there before fuses. What you penetrating with? What racking system you using? Shingle or metal roof? If shingle you doing the labor to pull shingles and put in flashing or you hacking it up with some HUGS/RT Minis? What's your max span between mounts given the wind load? S-5!s and HUGs add up fast when you can't get away with a large span. What's your interlock method? If you're landing in the MSP are you derating the mainbreaker? You value your time so little after all that material that you're still under $5k?

Edit: Also, you're gonna be paying a whole lot for LTL on that partial pallet of panels and 14' (if you get the short stuff) racking.

> Yes, lots of people want 34kw of standing load, because they want to ensure the offset of their HVAC unit.

The author of the post lives in the UK and averages 2kW load, a 4 kW PV system, and 45 kWh battery system. It's literally impossible for them to run a standing load of 34 kW for more than 1.5hrs without a grid tie. Why do you keep ignoring this?

Inrush is surge capacity. Starting a big motor like an air conditioner can require 2x or 3x the continuous running amps, but only for a few seconds.