KOSTAL Solar Electric: German-made PV and hybrid inverters, energy meters and home batteries

Overview

KOSTAL Solar Electric was set up at the end of 2006 as a joint inverter sales company. Solarserver reported in December 2006 that Freiburg module maker Solar-Fabrik AG and KOSTAL Industrie Elektrik GmbH of Hagen had founded it, with Solar-Fabrik holding 49%, an exclusive worldwide right to sell KOSTAL's inverters and operations starting on 1 January 2007. The first products were transformerless three-phase inverters up to 6 kW with built-in data storage and monitoring interfaces.

The business draws on the KOSTAL Group, a family-owned company with more than 100 years of history in automotive and industrial electronics. According to its company page, KOSTAL Solar Electric has since introduced its first three-phase inverter, the Smart Energy Meter and the ENECTOR wallbox, and it sells inverters that are developed and produced in Hagen, North Rhine-Westphalia, under a Made in Germany claim.

Its current direction is the complete home system. The PLENTICORE G3 works as a solar, hybrid or battery inverter, controls the wallbox directly and, since the October 2025 announcement of the KOSTAL battery, has a KOSTAL-branded LFP battery to go with it, while partner batteries stay compatible.

Offering

KOSTAL Solar Electric's inverter range covers homes, small businesses and commercial projects.

Inverters

The PLENTICORE G3 is a three-phase universal inverter in three classes: S (4 to 7 kW), M (8.5 to 12.5 kW) and L (15 to 20 kW), each upgradable by two power steps. It runs as a solar, hybrid or battery inverter, with a third DC input for a high-voltage battery, and with the KOSTAL BackUp-Switch it can supply a home on all three phases during an outage. Single-phase homes get the PLENTICORE MP in S (3.6 to 4 kW) and M (4.6 to 7 kW) classes. The PLENTICORE BI 25 is a 25 kW battery inverter for retrofitting storage, and the PIKO CI 30, 50 and 100 serve commercial rooftops and ground-mounted projects.

Meters, storage and charging

Two meters sit at the grid connection. The KOSTAL Energy Meter (KEM) measures all three phases in real time and passes the values to the inverter; it suits PLENTICORE G3 systems, PIKO CI G2 and ENECTOR G2 combinations up to 100 A. The KOSTAL Smart Energy Meter (KSEM) adds a web interface and computing power and is required for PIKO CI systems, transformer-metered connections above 63 A and older inverter and wallbox combinations. The HELIVOR HV is KOSTAL's LFP home battery, and ENECTOR is its wallbox.

Monitoring through the KOSTAL Solar Portal and the Solar4me app is free, and registering a system adds five years of material warranty to the five-year Smart Warranty.

Technology

PLENTICORE G3 inverters have two LAN ports, built-in Wi-Fi, four digital switching outputs, Modbus TCP and SG Ready, so they can steer heat pumps and wallboxes as well as report to an energy management system. Multi Device Control lets one host inverter control and monitor up to three inverters and up to three storage systems, and installers can reach an inverter remotely through the KOSTAL Solar Portal only with the owner's time-limited permission.

On PLENTICORE and PIKO IQ inverters, Modbus is switched on under Settings, Modbus / SunSpec (TCP), and the KSEM documentation asks for little-endian (CDAB) standard Modbus byte order when the meter talks to the inverter; the alternative is big-endian SunSpec order. Integration guides such as evcc's note that only one system may use the inverter's Modbus connection at a time and that external battery control has to be enabled with installer access.

The KEM talks to the inverter over a preconfigured Modbus RTU link. With PLENTICORE G3 and ENECTOR G2 the inverter controls the wallbox itself and the meter only supplies measurements; earlier systems left wallbox control to the KSEM. The HELIVOR HV deliberately has no Wi-Fi module of its own: firmware updates reach it only through the inverter, which keeps the battery off the home network.

Markets

KOSTAL Solar Electric's core market is residential and small commercial PV in Germany and the rest of Europe, where its customers are installers and the wholesalers who supply them. In March 2025 the Cologne wholesaler Segensolar added KOSTAL inverters to its range, citing Made in Germany production, cybersecurity, backup power and support for dynamic electricity tariffs; KOSTAL's DACH sales director Hans-Bernd Wiesener commented on the partnership.

The product choices follow German regulation and tariffs. Dynamic tariffs, SG Ready control and the ability to curtail production under § 9 EEG matter to German installers, and the move to a single inverter that runs the battery and wallbox targets households electrifying heating and transport at the same time.

Battery partners widen the market. Alongside its own HELIVOR HV, KOSTAL keeps third-party batteries compatible: in August 2024 ZYC Energy announced that its SIMPO HV storage, from 6.4 to 25.6 kWh per tower, works with the then newly launched PLENTICORE G3. Commercial buyers are served by the PIKO CI range up to 100 kW per inverter.

Company

KOSTAL Solar Electric GmbH is registered in Freiburg under HRB 700893, at Hanferstraße 6, Freiburg im Breisgau, according to its legal notice, which names Frank Henn and Manfred Gerhard as managing directors.

The company was founded in 2006 as a sales company for inverters made by KOSTAL Industrie Elektrik in Hagen, with Solar-Fabrik AG as a 49% partner and Christoph Paradeis as one of its two first managing directors. Today it presents itself as part of the KOSTAL Group, which describes itself as an independent family business for generations, based in 46 locations around the world (KOSTAL Group); the Solar Electric site gives 53 sites. Development and production of the inverters remain in Hagen.

In October 2025 the company announced its own battery, the HELIVOR HV, assembled by ZYC Energy in China with cells from Great Power; managing director Frank Henn presented it as completing the KOSTAL home system. Headcount and revenue are not published for the solar business separately from the group.