Indevolt SolidFlex 2000: Semi-Solid Balcony Battery at IFA 2026

Indevolt is one of the smaller names on the balcony-storage floor at IFA Berlin 2026 (4-8 September, Messe Berlin), but its SolidFlex 2000 is worth a look for one reason the bigger brands aren't shouting about: it uses a semi-solid-state LiFePO₂ battery rather than a conventional liquid-electrolyte pack. The rest of the spec sheet is familiar plug-in territory — four MPPT solar inputs, a bidirectional inverter, and modular expansion — but the chemistry, the 10-year warranty and the sub-£1,000 price make it a genuinely different proposition to the OUKITEL EP2500 and BLUETTI Balco 500 we've already covered from this year's show.

What the SolidFlex 2000 actually is

Coverage of Indevolt's IFA stand from German outlet MYC Media describes the SolidFlex 2000 as a plug-and-play storage unit that combines the battery, the MPPT charge controller and a bidirectional inverter in a single box. In practice that means it sits between your plug-in solar panels and a standard socket: solar comes in on the DC side, the battery stores what the house isn't using, and the inverter feeds it back out through the mains later. There's no separate microinverter to buy, and no installer visit for the basic setup.

The base unit holds 1.8kWh (Indevolt's own product page lists the expansion pack at 1,792Wh, so the headline figure is rounded up slightly) and weighs 21.5kg, with an IP65 rating that lets it live outdoors on a balcony or against a garden wall.

Four MPPT inputs and 2,400W of solar

The headline solar spec is four independent MPPT inputs at 600W each, for up to 2,400W of PV input across a 16-60V DC window. That's the same four-tracker layout OUKITEL is pushing on the EP2500, and it matters for the same reason: on a balcony you rarely get four panels facing the same way at the same tilt, so per-panel tracking stops one shaded module dragging the whole array down. In the UK the bigger constraint is that a plug-in system's export to the house is capped — our plug-in and balcony solar guide explains the 800W limit and the G98 notification rules that came in on 27 August 2026 — so a 2,400W solar input is really about filling the battery quickly on a bright day, not about running the house directly.

Output, expansion and the 2,400W bidirectional inverter

Indevolt quotes the inverter as bidirectional to 2,400W, but the AC output you actually get scales with how many batteries are attached. Per the SolidFlex 2000 product page:

• Base unit alone: 1,000W AC output
• With one SFA1800 expansion battery: 2,000W
• With two SFA1800s, or one SFA3600: 2,400W

Capacity expands to 22kWh with five expansion batteries on a single unit, and Indevolt says up to three units can run in parallel for a theoretical 66kWh and 7,200W of system power — well beyond what any balcony needs, and firmly into whole-home territory that overlaps with the AC-coupled EcoFlow STREAM 5000 we looked at recently. There's also an off-grid socket rated to 3,600W while grid-connected (2,400W when running purely off-grid), with a claimed 10-millisecond switchover if the mains drops.

Semi-solid LiFePO₂: the actual differentiator

Indevolt calls its cell technology CycBoost and quotes 8,000 cycles to 70% remaining capacity at full depth of discharge, a 15-year design life and a 10-year warranty. Semi-solid cells replace some of the liquid electrolyte with a gel or solid layer, which the industry pitches as safer under thermal stress and slower to degrade. It's worth being clear that “semi-solid” is a marketing term without a single agreed definition, and none of the cycle-life numbers have been independently verified, so treat them as Indevolt's claim rather than a proven figure. The operating range of -20°C to 55°C is standard for LFP.

A practical detail buried in the spec: Indevolt says a battery optimiser with active balancing lets new and older expansion packs mix in the same stack, which addresses a real complaint about modular systems where a battery bought two years later ages differently from the original.

SolidFlex 2000 ECO: the AC-coupled retrofit version

Alongside the standard unit Indevolt is showing the SolidFlex 2000 ECO, which strips out the MPPT inputs entirely and instead charges from AC behind an existing inverter — 896W of charge power on the base unit, rising to 2,400W with two expansion batteries. It's aimed at households that already have rooftop solar but no battery, and want to capture the export without touching the existing installation. This is the same retrofit logic EcoFlow is applying with its STREAM AC unit, and it's becoming the more interesting half of the balcony-storage market as a share of buyers already own panels.

Price and UK availability

Indevolt's European store lists the SolidFlex 2000 at €799 on promotion, against a €999 list price, and the ECO at €649 (down from €949). Indevolt does run a dedicated UK store, which currently front-lines its PowerFlex 3000 model at £799 — but at the time of writing we couldn't find the SolidFlex 2000 listed for sale in the UK specifically, so treat UK pricing and timing as unconfirmed. If it follows the PowerFlex's path, expect it to land at broadly the same sterling figure as the euro promo price. For context on what a fitted alternative costs, our home battery storage guide covers the installed end of the market.

What's still unconfirmed

The solar input, output tiers, capacity and euro pricing above are consistent between Indevolt's product pages and the IFA coverage. What we don't have is a UK launch date or sterling price for the SolidFlex 2000, any independent test of the 8,000-cycle semi-solid claim, or confirmation of how the unit behaves against the UK's 800W export cap out of the box (a firmware region setting is the norm, but Indevolt hasn't published one for this model). We'll update once UK stock appears.