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The short version
- Plug-in batteries are further behind than plug-in panels in the US. State laws were written around solar devices; grid-tied plug-in storage is less clearly covered.
- EcoFlow's STREAM line is the most complete US plug-and-play storage option, with availability rolling out state by state.
- A portable power station is the legal-everywhere alternative. It stores solar and runs loads from its own outlets without touching your home wiring.
- Several popular European balcony batteries aren't sold or certified for the US, so check the SKU before you import anything.
A plug-in solar system without storage has one big weakness: it only saves you money when the sun is up and your home is using power at the same moment. Anything extra is exported without credit, because state plug-in laws don't create net metering for these devices. A battery fixes that by soaking up midday surplus and releasing it in the evening, which is why balcony batteries have exploded in Europe.
In the US, the picture is messier. Some products sold as "balcony batteries" in Germany aren't certified for the US. Grid-tied plug-in storage isn't clearly covered by most state plug-in laws, which were written around solar generation devices. And the one thing a US buyer usually wants most from a battery, backup power during an outage, is something a grid-tied plug-in system can't provide by design.
This guide sorts the options into what you can actually buy and use in the US today.
Two ways to add storage
Grid-interactive plug-in storage. A battery-inverter unit sits between your panels and the outlet, stores surplus, and feeds your home through the same outlet later. This is the European model. It keeps everything automatic but inherits all of the interconnection and certification questions of plug-in solar, plus a few new ones.
Off-grid storage (portable power station). Panels charge a power station, and you plug specific appliances into the power station. Nothing feeds your home wiring, so there's no interconnection issue in any state, and when the grid drops, the power station keeps running. The trade-off is that it only powers what's plugged into it.
The picks
EcoFlow STREAM Ultra
$$$Best for: US buyers in supported states who want automatic storage
EcoFlow's US STREAM Ultra combines a hybrid inverter and battery in one unit, lists up to 1,200 W of grid-tied AC output through a standard NEMA 5-15 or 5-20 outlet, takes up to 2,000 W of solar input across four MPPT inputs, and adds dual AC outlets for direct loads. EcoFlow launched STREAM in Utah and has been expanding state by state, so confirm your state is supported and check the current certification listing for the US SKU.
Strengths
- Closest US equivalent to a European balcony battery
- Large solar input headroom
- Direct-load outlets as well as outlet feed-in
Trade-offs
- State-by-state availability
- Premium price tier
- Confirm local rules for grid-tied storage
LiFePO4 portable power station, 1 to 2 kWh
$$Best for: Renters and anyone in a state without a plug-in law
A mid-size LiFePO4 power station with solar input and pass-through charging is the most flexible way to store solar in the US. Charge it from balcony panels during the day, run a fridge, router or work setup in the evening, and keep it for outages. LiFePO4 chemistry is the right choice for daily cycling.
Strengths
- Legal in all 50 states
- True backup power
- Moves with you
Trade-offs
- Only powers what's plugged into it
- Manual load management
Expandable power station with add-on batteries
$$$Best for: Households that want to grow capacity over time
Expandable platforms let you start with one battery and add modules later. If you want several kWh of storage for evening loads and outage protection without a hardwired home battery, this is the most scalable non-interconnected route.
Strengths
- Scales with your needs
- High-output inverters run bigger appliances
Trade-offs
- Heavy and expensive at full size
- Solar input limits cap daily recharge
Anker SOLIX portable power station line
$$Best for: Buyers who want Anker's US-sold hardware
Anker's Solarbank balcony batteries are Europe-first, and independent reporting in 2026 noted they weren't UL-certified for the US market. Anker's US lineup instead centers on SOLIX portable power stations and its E10 whole-home backup system. For a plug-in panel setup, a SOLIX portable station charged from panels is the realistic US option.
Strengths
- Widely available in the US
- Strong app ecosystem
Trade-offs
- Not the same product as the European Solarbank
- Check solar input limits per model
Why a US-market SKU matters
Balcony storage is a European category first. Brands that sell hundreds of thousands of units in Germany may not sell the same product here, and a European unit won't carry US certifications, may assume 230-volt outlets, and won't have US warranty support. If a listing is shipping a European model to the US, skip it.
How to size storage for a plug-in system
Size storage around your surplus, not your whole home:
- Estimate daily production. Multiply your AC system size by your local peak sun hours. An 800 W system with 4 peak sun hours produces around 3.2 kWh on a good day.
- Estimate daytime self-use. Your fridge, router and standby loads use some of that in real time.
- Store the difference. If you typically use half of production during the day, about half is available to store.
- Allow for losses. Round-trip battery efficiency isn't 100 percent, so add some headroom.
For most plug-in systems, that lands between 1 and 3 kWh of storage. More storage than your panels can refill is dead weight.
Grid-interactive plug-in systems shut down in an outage for lineworker safety. If surviving outages matters, a portable power station or an expandable station is the right tool, even if you also own a plug-in kit.
What to compare when shopping
- Usable capacity (kWh). Look for usable rather than nominal capacity; some units reserve a buffer.
- Solar input limits. Check both maximum watts and the voltage window. Two residential panels in series can exceed the input voltage of smaller power stations, so confirm before wiring.
- Continuous AC output. A fridge, a window AC or a microwave needs more headroom than a router and lights. Surge rating matters for compressor loads.
- Pass-through charging. The unit should run loads while charging from solar without constantly cycling the battery.
- Cycle rating and warranty. For daily use, favor LiFePO4 cells rated for thousands of cycles and a multi-year warranty on the US SKU.
- App and scheduling. Time-of-use scheduling lets you charge from the grid when it's cheap if your utility has TOU rates, then discharge at peak.
- Noise and cooling. Fanless designs are quieter in apartments; units with fans are fine in a garage or utility closet.
Common mistakes
The first mistake is buying storage bigger than your panels can refill; an 800 W balcony array can't top up a 5 kWh battery on a short winter day. The second is importing a European balcony battery because it looks slick in reviews. The third is expecting grid-interactive storage to keep the lights on in an outage when the product documentation says otherwise. Read the backup section of the manual before you buy.
Safety and placement
- Keep batteries indoors or in a shaded, ventilated spot. Heat shortens battery life; freezing temperatures block charging on most lithium chemistries.
- Don't daisy-chain outlets. Plug power stations and storage units directly into the wall.
- Watch weight on balconies. Batteries are dense; floor load limits matter in older buildings.
- Use the manufacturer's cables and don't exceed rated solar input voltage.
The bottom line
If your state is supported and you want an automatic, European-style setup, EcoFlow's STREAM line is the clearest US option. Everyone else, especially renters and people in states without a plug-in law, will get more usefulness from a LiFePO4 power station charged by balcony panels. Pair either with an energy monitor so you can see how much surplus you're actually capturing, and check your state's status in our plug-in solar law guide.
For storage and off-grid systems we also track Bluetti power stations and Renogy panels, charge controllers and batteries direct from the brands.
Frequently asked questions
Can I add a battery to a plug-in solar kit?
Yes, but options vary by state. EcoFlow's STREAM units are designed for this in supported US states. Otherwise, a portable power station charged by your panels stores energy without connecting to home wiring.
Will a plug-in solar battery power my home during an outage?
A grid-interactive unit feeding through the wall outlet shuts down in an outage. Some units have dedicated outlets that can run loads directly; a portable power station always can.
Is the Anker Solarbank sold in the US?
The Solarbank balcony batteries have been Europe-first, and 2026 reporting noted they weren't UL-certified for the US. Anker sells SOLIX portable power stations and the E10 whole-home system in the US.
How much battery do I need for a plug-in solar system?
Most plug-in systems pair well with 1 to 3 kWh of storage, sized to the surplus your panels produce beyond daytime use.
What battery chemistry is best?
LiFePO4 (lithium iron phosphate) is the best choice for daily cycling thanks to long cycle life and thermal stability.