Polarium: Lithium-ion backup batteries for telecom sites and distributed storage

Overview

Polarium was founded in Stockholm in 2015 as Incell International, selling lithium-ion backup batteries to telecom operators and tower companies as a replacement for lead-acid batteries and diesel generators. It took the Polarium name in November 2020, when it announced its move into commercial and industrial storage; at that point it reported more than 250,000 installations in over 50 countries.

From telecom backup to distributed storage

Growth was fast through 2021, when the company reported net sales of SEK 1.1 billion, and in 2022 a pension-fund investment valued it at US$1 billion. The years since have been harder. Sales fell to SEK 896 million in 2025 with an EBITDA loss of SEK 61 million, the company closed its Mexican production and recapitalised with SEK 500 million of convertible preference shares.

What sets it apart

Its distinctive asset is the installed base. Telecom backup batteries sit at thousands of sites, and Polarium now aggregates the spare capacity of such distributed batteries into a virtual power plant. In April 2026 RWE agreed to trade at least 50 MW / 135 MWh from more than 1,600 Polarium systems in Germany from late 2026. The company also stresses that its electronics, firmware and cloud are developed in Sweden with data kept in the EU.

Offering

Telecom batteries

The core line is 48 V rack batteries for telecom power systems, in 19 inch and 23 inch formats with LFP (iron-based) or NMC (nickel-based) cells. The 19 inch 3U 100 Ah LFP battery weighs 38.3 kg, charges at up to 100 A down to -5°C and is rated for about 8,000 cycles; the 19 inch 4U 150 Ah LFP model weighs 59 kg and is offered as a Connected Battery. A 23 inch 2U nickel-based model is listed at 180 Ah. Connected Batteries add a cellular modem for remote monitoring, firmware updates over the air, GPS, Wi-Fi and Cell ID tracking, geofencing and remote disabling of stolen units.

Storage systems

Polarium BESS is a modular cabinet system with cylindrical cells, pre-assembled with battery modules and inverters, for peak shaving, backup, self-consumption, grid services and EV charger power boost. Its high-voltage strings run from 6 modules (63 kWh, 307 V) to 17 modules (178 kWh, 869 V), per the battery page. The Power Skid, launched in June 2024, puts up to 12 cabinets and 600 kW on a steel frame in a 20-foot container footprint.

Home and software

Polarium HomeBattery is an all-in-one home system; the second generation, launched in February 2026, integrates a 12 kW hybrid inverter and is sold through partners including Svea Solar and Greenely. Earlier, Polarium built the Homevolt home battery with Tibber. Software spans Polarium Fleet Management, an EMS for scheduling against prices and a VPP platform.

Technology

Battery management and interfaces

Each Polarium battery carries its own BMS, which reports state of charge and state of health and supports remote management. Polarium's patented Current Limiting Device limits charging voltage at the cell level, which the company says lets its batteries work with any rectifier without current control from the power system, according to its 2020 product release. The 100 Ah LFP product page claims "the widest communication compatibility on the market" for telecom and inverter-based equipment, but no public datasheet, register map or protocol list backs this up. Buyers cannot see from the website which bus or protocol a given model uses.

Remote management

Connected Batteries talk to the Polarium Cloud over cellular links, using encrypted traffic and an operator-originated VPN, with Telenor Connexion as connectivity provider since 2023. Fleet Management shows per-battery data, firmware status and alarms, and warns when operating conditions risk breaching warranty terms.

Integration with energy markets

For trading, RWE connects to Polarium's platform through a single technical interface. In Germany, smart meter gateways from metering operator inexogy measure and control the distributed systems. At Recharge's Malmö charging site, a third-party energy management platform handled the protocol translation needed to add Polarium BESS to the charger network.

Development and safety

Electronics and firmware are developed in Sweden. The 2,000 square metre Polarium X centre in Tomteboda, Stockholm, runs cell, module and climate testing from -40°C to +60°C. The company reports completing UL 9540A unit-level fire propagation testing in 2023.

Customers

Telecom operators and tower companies

Telecom operators and tower companies were Polarium's first customers. Telia, the Swedish operator, ordered lithium backup systems with remote monitoring in 2016, ran a two-site energy optimisation pilot from January 2022 that Telia Company announced alongside Polarium, and hosts the PTS-funded Offgrid Roslagen project. There, ten Polarium 100 Ah batteries work with solar panels and hydrogen fuel cells in a system that the company says extends a base station's backup from a few hours to up to 110 days.

American Tower's African subsidiary has worked with Polarium since 2017. In 2021 it signed a multimillion-dollar bulk purchase agreement that supported Polarium's Cape Town factory; ATC Africa reports that switching from diesel and lead batteries cut its Scope 1 emissions by more than 50% since 2018.

Commercial, industrial and EV charging

Kempower, the DC fast charger maker, partnered with Polarium in February 2024 to pair BESS with its chargers for sites with limited grid capacity. Recharge uses Polarium BESS at a high-power charging site in Malmö for peak shaving, power boost and arbitrage, with expected peak shaving savings of about SEK 5,500 a month. In the Nordics, Polarium bought the BESS engineering and installation firm Stella Futura in June 2025.

Energy market partners

RWE will trade Polarium's aggregated German capacity from late 2026, and inexogy is fitting smart meters to the German fleet, starting with more than 1,600 systems and aiming for up to 10,000, under service agreements running to 2029.

Markets

Polarium reports installations in 80 countries and more than 540,000 batteries installed, according to its about page. Its customer base runs from sub-Saharan Africa, where tower sites lack reliable grid power, to the Nordic countries and the Arctic.

Segments

Since 2024 the business has been organised around telecom, commercial and industrial, and residential customers, with EV charging infrastructure as a further segment on the website. In August 2026 the company narrowed its focus to telecom power and distributed energy storage, arguing that batteries placed at existing customer sites can be brought into service in months, where large grid-scale projects take years.

Geography

Germany is where the distributed storage fleet is being built, with a virtual battery of more than 1,600 behind-the-meter systems expected by late 2026 and a stated goal of around 300 MW / 810 MWh across more than 10,000 systems. Sweden and the Nordics are home markets for C&I and residential products, and Stella Futura extends project delivery there. The company opened a US sales office in Littleton, Colorado, and earlier releases list sales presence in Indonesia, New Zealand, South Africa and the UK.

Company

Headquarters and legal entity

Polarium Energy Solutions AB (registration number 556986-5461) is a privately held Swedish company headquartered at Solnavägen 3H in Stockholm, per its contact page. It runs R&D offices in Oskarshamn and Sundsvall and the Polarium X technology centre in Solna.

Manufacturing

Production in Guadalajara, Mexico started in February 2018 as the configuration and logistics centre for the Americas. A factory in Hai Phong, Vietnam followed in 2021 after an SEK 20 million investment. A Cape Town factory opened on 28 April 2022, which the company says can produce more than 300,000 batteries a year (4 GWh) when fully operational. In May 2024 Polarium announced it would move all Mexican manufacturing to Stockholm, Vietnam and South Africa by 30 June 2024. A Stockholm site, Polarium X2, opened in 2024 to build Homevolt home batteries.

Funding and finances

In May 2022 the pension company AMF invested SEK 955 million at a US$1 billion valuation, followed by SEK 178 million from three Swedish investors in June 2022. In October 2022 Alecta, Formica Capital and Absolute Unlisted bought more than SEK 1.1 billion of existing shares. In October 2024 existing investors added SEK 500 million in convertible preference shares. Net sales were SEK 1,332 million in 2024 and SEK 896 million in 2025.