EcoFlow Delta Pro 3 vs Bluetti AC500 + B300K: Which Belongs in Your Home?

By Nacho Iniguez ✦ Updated June 5, 2026

If you have spent any time shopping for a serious home backup battery, these two systems keep showing up side by side, and for good reason. The EcoFlow Delta Pro 3 and the Bluetti AC500 paired with the B300K battery both sit at the top of the direct-to-consumer market, both push 240V split-phase power, and both can grow into something that backs up most of a house. But they are built on two different philosophies, and that difference matters more than any single spec.

I want to be upfront about what this article is. I have not bench-tested both units in my own panel; the numbers below are the published manufacturer figures for 2026, labeled as such. Real-world output always lands a bit under the spec sheet once you account for inverter losses and temperature. With that caveat set, here is how they actually compare.

The core difference: one box vs a hub and battery

This is the single most important thing to understand before you compare anything else.

The Delta Pro 3 is an all-in-one machine. Battery cells and inverter live in the same case. You plug it in, it works, and you can add expansion batteries later if you want more runtime.

The AC500 is not a battery at all. It is an inverter hub, the brain and the muscle, with zero internal storage. It does nothing until you bolt a B300K battery module onto it. That is why you almost never see the AC500 sold alone; the standard buy is “AC500 + B300K.” The upside is that you choose exactly how much battery you stack underneath it. The downside is more boxes, more cables, and more upfront thinking.

Neither approach is better in the abstract. They suit different buyers, which is the whole point of this comparison.

Manufacturer spec comparison

These are the published specifications as of 2026. Treat output and recharge figures as manufacturer claims, not measured results.

A few honest reads on that table. The AC500 has the bigger inverter, so it starts more heavy motors and runs more simultaneous loads. The Delta Pro 3 carries more capacity in its base box and recharges noticeably faster from the wall. Bluetti claims more cycles; EcoFlow claims a far higher ceiling on total expansion. Prices drift with promotions, so confirm current numbers before you buy.

Which one starts your hard loads

If your backup plan includes a well pump, a central AC compressor, or a large air handler, the surge spec is where you look first. The AC500’s 5,000W continuous and 10,000W surge (manufacturer figures) give it more headroom than the Delta Pro 3’s 4,000W continuous and 6,000W X-Boost surge.

That does not mean the EcoFlow cannot run heavy appliances. Its X-Boost feature trims voltage to coax stubborn motors to start, and 4,000W covers the vast majority of homes that are not trying to run everything at once. But if you already know you have a demanding 240V load, the Bluetti has more comfortable margin. Run your actual numbers through our battery sizing calculator before you trust any single watt rating.

Capacity and expansion paths

Out of the box, the Delta Pro 3 gives you more usable energy: 4,096 Wh versus 2,764 Wh in a single B300K. So if you buy one unit and stop there, EcoFlow stores more.

The story flips when you start stacking. The AC500 is built to grow; add B300K modules up to roughly 18,432 Wh on a single hub, and pair multiple hubs for true whole-home coverage. EcoFlow counters with an even higher published ceiling near 48 kWh when you chain its expansion batteries, though reaching that number is a serious investment in both money and floor space.

The practical question is how you want to spend. Bluetti’s modular path lets you buy storage in chunks as your budget allows. EcoFlow’s path is simpler but tends to commit you sooner. Either way, model the payback with our solar and battery ROI calculator so the expansion does not outrun its value.

Living with each one day to day

Recharge speed is where EcoFlow pulls ahead for everyday use. Filling to 80% in roughly 50 minutes from a standard outlet is genuinely useful when a storm window is short or you are topping up between grid dips. The AC500 draws less from the wall and takes longer to refill, especially once you have several batteries stacked.

For solar self-supply and time-of-use bill shaving, both pair with panels and both handle pass-through power. If your goal is shifting energy to dodge peak rates rather than pure backup, see how the math works in our time-of-use arbitrage calculator. And if you are still deciding whether any of this pencils out against the grid, start with is solar worth it in 2026.

One more note on noise and footprint: the Delta Pro 3 is one wheeled box you can move alone. The AC500 plus its batteries becomes a small stack that mostly stays put. Neither is wrong; they just live in your space differently.

The verdict by use case

There is no single winner here, so pick by what you actually need.

Buy the EcoFlow Delta Pro 3 if you want one box that works the moment it arrives, you value fast wall recharging, and you would rather not think about hubs and modules. It is the cleaner choice for a renter, a smaller home, or anyone who wants backup without a project.

Buy the Bluetti AC500 + B300K if you want the biggest inverter for hard 240V loads, you like buying storage in stages, and you are comfortable building a small system. It rewards the planner who intends to grow.

For deeper single-unit breakdowns, read our full EcoFlow Delta Pro 3 review and our Bluetti AC500 + B300K review. If you are weighing these against other contenders, our roundup of the best home backup batteries for 2026 puts them in context, and you can browse every teardown in the reviews hub or the wider guides library.

A closing word of honesty: spec sheets sell, but your loads decide. Add up what you truly need to keep running, size for that with a little margin, and the right unit usually picks itself.