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Frequently Asked Questions

In this Frequently Asked Questions (FAQ) you will find a collection of answers to frequently asked questions about a specific Voltfang topic or service.

You have not found an answer to your question here? Then please feel free to contact us. There you will receive individual advice on your storage project.


As each project has individual requirements, it is unfortunately not possible for us to give exact prices. However, we understand how important a rough price indication is for you. We are therefore happy to provide you with non-binding and approximate price information as soon as you request a quote and possibly have a free electricity analysis carried out.

The free electricity analysis enables you to obtain further information on the economic efficiency of your project. This enables us to help you find the right solution for you. Make an offer

To check whether a commercial storage unit is suitable for you, the first step is to fill in our non-binding offer form. If you are deemed suitable, we will determine the right storage system together in the second step in a personal meeting or by exchanging contacts.

The required storage size depends on your electricity consumption, the largest consumers (e.g. electric car, heat pump) and the performance data of your solar system or CHP unit. The independence calculator can give you an initialassessment.

The Voltfang battery storage system is an all-in-one solution. You will receive the battery storage system including a battery inverter. In addition, our prices always include transportation to the installation site, installation and commissioning as well as registration with the grid operator. We then guarantee permanent online monitoring of the storage system. This allows us to prevent errors in the system and rectify them remotely. We also promise to take back the battery modules free of charge at the end of their service life. In this way, we enable a secure return flow into a fully-fledged recycling process from our partner network.

Our battery storage system basically meets the requirements of many subsidy programs for storage systems. We have already received a firm commitment from the development bank in Lower Saxony (N-Bank) and in Austria (OeMag). (as of 2023) We are currently reviewing other country-specific funding programs.

The Voltfang battery storage system is manufactured in our production facility in Aachen (NRW). By reusing the used electric car batteries, no further critical resources are used for production.

With the Voltfang battery storage system, you can increase your own consumption, reduce expensive peak loads, charge electric cars with your own electricity, protect yourself against power outages and/or even supply your company completely independently.

2nd Life

There are currently no economic recycling options for current lithium-ion batteries from electromobility. Combined with the increasingscarcity of rare earths, which are essential for batteries currently in use, a 2nd life use of vehicle batteries offers the possibility of maximizing battery life. Discarded vehicle batteries generally have a residual capacity of over 80% dueto ageing and are therefore ideal for use in stationary storage systems. This enables a cost-efficient product, offers a further life phase for used vehicle batteries and ultimately protects the environment.

We source our car batteries directly from well-known German vehicle manufacturers.

The battery modules are tested according to international standards using our specially developed test procedure. If the modules pass the test and meet our requirements, they are processed by us and approved for reuse in a battery storage system.

After 2nd life use in the stationary battery storage system, the battery modules are distributed within our partner network of recycling companies. In this way, we ensure that the valuable resources are returned to the sustainable circular economy (closing the loop).

We offer our customers a 10-year warranty promise with our Batteryflat. This ensures that the battery modules can be replaced when performance drops. This is achieved through an operation-optimized battery life window and the application of our gentle battery charging algorithm. In addition, we guarantee the quality and durability of the battery modules used through our developed test procedure.

Taking a 10 kWh battery storage system as an example, up to 1 t of CO, 3 MWh of energy and 50 kg of resources can be saved compared to a conventional battery storage system,2for which new batteries would have to be produced (see Emilsson et al., Lithium-Ion Vehicle BatteryProduction, 2019)

First of all, we ensure the safety of the installed battery modules at cell level by subjecting them to our battery testing procedure and preparing them accordingly for 2nd life use. The test procedure is based on UN 38.3 and therefore fulfills all requirements for 2nd Life batteries. In addition, our storage systems meet the state of the art in battery storage guidelines, directives and standards and are marked with European CE conformity.


The system is an AC-side battery storage system. This means that the system is connected to the building power grid behind the PV inverter on the 230 V AC side. The advantage is a very quick and easy installation, as well as the possibility of integrating the battery storage into any existing PV system.

The basic version of the battery storage system is single-phase. If a three-phase system is required, this can be selected as an additional option.

Der Batteriespeicher wird Ende dieses Jahres notstromfähig sein. The basic version is single-phase, which means that only the essential parts of the building can be supplied in the event of a power failure. However, we also offer the option of ordering the battery storage system as a three-phase variant. In this case, for example, an entire production hall can be supplied with energy at any time, both with and without a grid connection. This gives you the flexibility to choose the right solution for your needs.

Thanks to the AC-side design, the battery storage system can be integrated into any existing system. The existing inverter remains in use and an additional Voltfang inverter is integrated. Currently, only the Voltfang internal web app can be used for visualization. In the future, however, we want to enable integration into existing energy management systems.

An external current sensor at the building’s power connection point tells the electricity storage control system whether the electricity generated by the PV system can currently be consumed in the building. If electricity production exceeds current consumption, the battery storage system is charged. If the storage system is full and the photovoltaic system is still producing more electricity than is needed in the household, the surplus electricity is fed into the grid. If the electricity consumption of the building exceeds the production of the PV system, the building is supplied via the battery storage system.


The installation of a Voltfang battery storage system is carried out by our specialist partner network of competent electricians and PV installers. After a consultation and order has been placed, we inform our partner network, which installs the Voltfang within approx. two weeks according to the Plug&Play principle.

The Voltfang battery storage system independently monitors the health of its batteries. If an irregularity is detected, the battery storage system intelligently decides on further measures. As a rule, members of our service team will be notified who will resolve the problem directly via theremotemaintenance function. In case of severe disruptions, the battery storage system can autonomously disconnect the batteries from the grid and notify both our service team and the customer. If on-site maintenance is necessary, our service technicians will come to your location and resolve the issue.

Voltfang battery storage systems can be used in conjunction with all standard PV systems on the market. Existing inverters and solar control systems can be integrated into the system.

Any existing wallbox can be powered by the battery storage system.

It is not yet possible to integrate vehicles into our storage system. As soon as car manufacturers enable bidirectional charging, the battery storage system will be adapted.

Like all other consumers, heat pumps can be used together with the battery storage system. However, due to the high power consumption of a heat pump, this should be given special consideration when designing a suitable storage tank.

Voltfang currently supplies and operates the battery storage systems exclusively in Germany and Austria. In the future, however, we want to expand our range to other European countries.

We currently offer the option of purchasing our battery storage systems either via an inquiry on our website, by telephone or via our partner network. Our team is always available to process your inquiries and help you choose the right battery storage system.

Customers of our Voltfang battery storage system can call up its charging status and other useful information directly via ourweb app. We are currently working on offering this information in our own smartphone app and for common smart home solutions.

Voltfang Industrial

Since each project has its own unique requirements, we are unfortunately unable to provide exact pricing information. However, we understand how important a rough price indication is for you. Therefore, we are happy to provide you with a non-binding and approximate price estimate once you request a quote and possibly conduct a free power analysis.

The free electricity analysis enables you to obtain further information on the economic efficiency of your project. This enables us to help you find the right solution for you. Make an offer

In principle, our Voltfang Industrial is installed in a fireproof room. However, starting this year, we also offer an outdoor version that can be flexibly installed at various locations. This outdoor version enables versatile use of the Voltfang Industrial regardless of location. If you have any questions or are interested in one of the two options, please do not hesitate to contact us.

The Voltfang Industrial consists of two main components, the external inverter and the battery cabinet. The inverter is included in the price and is mounted on a wall near the battery cabinet. It can be configured independently of the battery cabinet and is therefore perfectly adaptable to customer requirements. The battery cabinet contains the battery management unit (controller) and the battery modules.

The Voltfang Industrial is characterized by its modular design. A battery cabinet has the dimensions (WxDxH) 800 x 600 x 2000 mm and can contain up to 8 battery modules, which enables a maximum capacity of approx. 33 kWh. If more energy is required, up to 10 battery cabinets (1 MWh) can be added to the side.

An external inverter is also available, which measures (WxDxH) 275 x 147 x 546 mm in the basic version and can be mounted on a wall. This inverter enables the stored direct current to be converted into usable alternating current.

Our modular system allows you to adapt the capacity and performance of the Voltfang Industrial to your individual requirements.

We currently use KACO and Sinexcel inverters. Depending on the application, the individual models can be flexibly combined up to 920 kW so that we can provide every customer with the right power. The following models can be used:

  • KACO blueplanet gridsave 50.0 TL3-S
  • KACO blueplanet gridsave 92.0 TL3-S
  • Sinexcel PWS2-(29P,30P)-EX

Yes, the capacity can be increased at any time. Additional modulescan be added to an existing battery cabinet or another battery cabinet can be added.