Why does a data sheet show more than 800 W output?

Some units list a combined or off-grid AC output that is higher than the grid feed-in. The grid feed-in must still be set to the legal limit in your country. Check the manual for how the limit is configured.

Can I combine batteries from different brands?

Expansion modules are almost always brand- and model-specific. Plan expansion within one system, and check compatibility before buying additional modules.

What does DC-coupled mean here?

The panels connect directly to the battery unit, which stores the direct current before converting it. That avoids one conversion step compared with batteries that charge from a socket, which usually helps efficiency.

Is a portable power station an alternative?

Some power stations can take solar input and run devices, but most are not designed to feed into your home wiring. For backup and mobile use they can make sense; see our power station comparison.

Plug-in solar battery systems compared (data sheets)

Plug-in solar batteries have converged on one main design: an all-in-one unit that the panels plug into directly, with roughly 2 to 2.7 kWh of storage per module, several solar inputs and a built-in inverter that feeds the socket up to the legal limit. Where they differ is in expansion, control, backup options and fit with your existing kit. The table below compares three widely sold systems from their published data. These are data sheet and retailer values, checked October 2026; we have not tested the products.

Data sheet comparison

	Anker SOLIX Solarbank 3 E2700 Pro	Zendure SolarFlow 800 Pro	EcoFlow STREAM Ultra
Capacity per unit	2.688 kWh	1.92 kWh	1.92 kWh
Maximum system capacity	up to about 16 kWh with expansion modules	up to 11.52 kWh with expansion modules	see data sheet
Solar inputs	4 MPPT	4 MPPT	4 inputs, 500 W each
Inverter	built in, grid feed-in 800 W	built in, grid feed-in set to legal limit	built in, AC output listed up to 2,300 W
Coupling	DC (panels into the unit)	DC (panels into the unit)	DC (panels into the unit)
Ingress protection	IP65	IP65	IP65
Operating temperature	−20 to +55 °C	−20 to +55 °C	−20 to +55 °C
Cycles stated	6,000+	see data sheet	6,000+
Off-grid socket	see data sheet	see data sheet	see data sheet
Warranty	see manufacturer terms	see manufacturer terms	see manufacturer terms
Checked	October 2026	October 2026	October 2026

Notes on the table: Zendure has introduced a successor model, SolarFlow 800 Pro 2, with similar headline figures. Where a unit lists an AC output above 800 W, that refers to output modes other than grid feed-in; feed-in must be limited to what your country allows. Check every figure against the current manufacturer data sheet before buying, because model ranges change frequently.

What the columns mean

Capacity and expansion

Capacity is the energy the battery can hold. Usable capacity can be a little lower than the nominal figure, depending on the manufacturer. Expansion modules let you add capacity later, but only within the same product family. For plug-in solar, more capacity only helps if your daily surplus fills it; see plug-in solar with a battery for the calculation.

Solar inputs

Four inputs allow up to four panels, or two pairs facing different directions. Each input has its own tracker, so shading on one panel does not pull down the rest. The total feed-in remains capped. More on inputs and trackers in our guide to microinverters.

Control: fixed output or following consumption

A battery saves money when it releases power while you are using it. Two control methods are common:

Schedule or fixed output: the battery releases a set wattage at set times. Simple, but it may export stored power or leave consumption uncovered.
Meter-led output: a meter reader or smart plug reports your consumption, and the battery releases only what you need. This is the approach described in zero export with a smart meter reader.

Off-grid socket

Some units have a separate socket that keeps working during a power cut, independent of the grid-tied output. That is not the same as whole-home backup: only devices plugged directly into that socket keep running. If backup matters most, compare with portable power stations.

Temperature and placement

Batteries are usually placed on the balcony or near the panels. The stated operating range tells you whether the unit can stay outside in winter and summer. Charging lithium batteries in frost is typically restricted by the battery management system, which reduces winter use.

Rules to keep in mind

Great Britain: reporting on the plug-in rules in force since August 2026 says that battery systems which import and export through a socket are outside the first set of rules. Check the official position in SI 2026/848 before buying; see the UK and Ireland rules.
Germany and the EU: feed-in remains limited to the national cap, and registration applies to the whole system.

Before you buy

Estimate your daily surplus on a sunny day.
Choose a capacity that matches it, with expansion as an option rather than a starting point.
Check compatibility with your panels (voltage, power per input).
Decide whether you need meter-led control, and which meter reader the system supports.
Read the warranty terms: years, cycles and guaranteed remaining capacity.

Larger home batteries connected by an installer are a different category; see how big a home battery should be.