Victron is bullet proof. I've seen their inverters used aboard working vessels for decade after decade without so much as a glitch. Highly recommended.

Looked them up and for LiFePo4 batteries they seem to charge several times the eBay prices. What could they possibly be offering at that premium, given that it's almost certain they don't make the batteries themselves?

Victron isn't exactly a bargain basement supplier, the people that buy their stuff depend on it for their lives. Their quality control, spares supplies and longevity are second to none, that goes for chargers, inverters and battery systems. If you're not worried about having power, having your inverter fail when you need it most, have your batteries in an outdoor enclosure of their own then you can skimp on all of this, probably cheapest option would then be to use reclaimed batteries and some cheap Chinese sine wave (for some definition of sine wave, most of them are 4 bit modified square wave that are run through a large transformer to smooth out the curve) inverter. That way you get a lot of bang for your buck, and even if the inverter ever dies you can just get a new one.

But when you are putting together a system that simply needs to work and that outputs clean power then you have very few companies that are that well supported. I've used Xantrex, Sunpower, Victron, ABB and a bunch of noname stuff. I'm sure there are plenty of others. The only one that comes close in design quality is ABB, Xantrex used to be good but it has gone down tremendously in the last decade and a half, the remainder I will never use again.

They're already top balanced grade A cells versus grade B cells. They're also the cells used in industrial mining, so they're able to tolerate vibration and movement.

> Why buy something that might explode from a trustworthy business, when it's cheaper out the back of some dudes car.

IIRC one of the main advantages of LiFePo4 batteries is that they can't "explode" under the normal circumstances. And if they buy batteries in China anyway, then why not buy from China as well? I'd understand 20-30% premium, but not 200-300%.

Think 'hospital', certified power, military, off-shore (vessels, platforms, emergency power and so on).

For a system that is bullet proof and where there are very strict requirements it makes sense to spend that money, for your homebrew system it likely doesn't, but you can pick up their inverters for a good discount at the various surplus auction sites with some regularity and that's the best of both worlds: great quality at a reasonable price.