Modular Whole-Home Power Systems Compared: Delta Pro Ultra vs EP900 vs SOLIX E10

Portable power stations top out around 6-7kWh and whole-home battery installs like the Tesla Powerwall start north of $12,000 installed. Sitting between those two tiers is a newer category: modular, expandable “power hub” systems that ship as a portable base unit but can grow into something close to whole-home backup by adding battery packs over time. The Anker SOLIX E10, the Bluetti EP900 + B500, and the EcoFlow DELTA Pro Ultra are the three systems leading that category right now, and they solve the same problem in noticeably different ways.

What “Modular Whole-Home” Actually Means

Each of these systems starts as a single unit you can buy today and expand later by adding battery modules, rather than committing to a full-capacity system on day one. That matters because whole-home battery needs are rarely obvious in advance — most owners underestimate how many kWh they actually need until they’ve lived through an outage. A modular system lets you start with backup for a few critical circuits and scale toward whole-home coverage as budget allows, without replacing the core unit. All three systems here are UL-listed for safety, but they differ meaningfully in starting capacity, how far they can expand, and how much continuous power they can deliver to your panel at once.

Anker SOLIX E10

The SOLIX E10 is the most affordable entry point of the three, starting around $4,299 for a single Power Module paired with one B6000 battery pack, which puts you at roughly 6kWh of usable capacity. Each Power Module supports up to five B6000 packs, and the system is designed to wall-mount or sit on the floor, which makes it a reasonable fit for a garage or utility room install rather than a purely portable unit. Paired with Anker’s Power Dock, continuous output climbs to 9,600W, enough to run a well pump, a mini-split, and general household circuits simultaneously. It carries dual UL9540 and UL9540A certification — the same fire-safety testing standard that governs permanently installed home batteries — and a 5-year warranty. If you’re deciding between this and a dedicated installed battery, our SOLIX E10 vs. Tesla Powerwall 3 comparison breaks down where the E10 actually competes and where it doesn’t.

Bluetti EP900 + B500

The EP900 is the largest and most expensive system of the three, and it’s built more like a small installed battery than a portable power station. The base configuration pairs the EP900 inverter with two B500 battery packs for 9.92kWh of usable capacity, expandable to 19.84kWh with four B500 units. Continuous output is 9,000W at 240V, which is enough to run genuinely large loads — a central AC compressor and an electric range at the same time, for example. Pricing starts around $9,490 for the base setup and climbs toward $15,000 fully expanded, and Bluetti backs it with a 10-year warranty, double the coverage of the other two systems here. It ships with a sub-panel and mounting hardware, and Bluetti offers optional professional installation for owners who don’t want to do the electrical work themselves. We cover the tradeoffs of this tier more broadly in our full Bluetti home battery review.

EcoFlow DELTA Pro Ultra

The DELTA Pro Ultra sits closest to the SOLIX E10 on starting price — around $4,099 on current promotional pricing — but it has by far the highest expansion ceiling of the three, with EcoFlow rating stacked-inverter configurations up to roughly 90kWh. A single base unit holds 6,144Wh and outputs 7,200W continuously; stack multiple inverters together and that output scales to 21.6kW, which is genuinely whole-home territory. It carries UL1973 and UL9540 certification and a 5-year warranty on the core device. The standout feature is native integration with EcoFlow’s Smart Home Panel 2, which handles automatic circuit switchover during an outage the same way a traditional automatic transfer switch would. If you’re still deciding between EcoFlow and its closest competitors at the portable tier, our DELTA Pro 3 review and our EcoFlow vs. Jackery vs. Bluetti comparison cover how the Ultra’s smaller sibling stacks up against the field.

Capacity, Output, and Price at a Glance

For a quick gut-check: the SOLIX E10 wins on entry price and per-module simplicity, the EP900 wins on continuous output and warranty length at the cost of the highest sticker price, and the DELTA Pro Ultra wins on raw expansion ceiling if you think you’ll eventually want true whole-home coverage. None of the three is “best” in isolation — the right pick depends on how much capacity you need on day one versus how far you expect to grow, and whether you value a longer warranty over a lower initial cost. Before comparing any of these against a permanently installed system, it’s worth running your actual numbers through our ROI calculator and our battery and inverter sizing guide so you’re comparing against your real household load rather than a marketing spec sheet.

Which One Actually Fits Your Situation

If your goal is backing up a handful of circuits — refrigerator, WiFi, a few outlets, maybe a window AC unit — and price is the deciding factor, the SOLIX E10’s low entry cost makes it the easiest starting point, with room to add capacity later. If you want something closer to a true whole-home system without pulling permits for a full installed battery, and you’re comfortable with the higher upfront cost, the EP900’s higher continuous output and 10-year warranty make it the more durable long-term choice. And if you’re not sure how far you’ll want to expand and would rather buy into a platform with headroom than get boxed in by a hardware ceiling, the DELTA Pro Ultra’s 90kWh expansion path gives you the most runway without switching systems entirely.

Bottom Line

All three systems prove the same point: you no longer have to choose between a portable power station and a fully installed whole-home battery. The SOLIX E10 is the budget-friendly starting point, the EP900 is the higher-output, longer-warranty option built for larger continuous loads, and the DELTA Pro Ultra offers the most room to grow if whole-home coverage is the eventual goal. Match the choice to how much capacity you need right now, not how much you might want someday — all three let you add more later.