Low-voltage or high-voltage battery storage - 1-phase or 3-phase inverter - What are the advantages and disadvantages?

Low-voltage or high-voltage battery storage - 1-phase or 3-phase inverter - What are the advantages and disadvantages?  - 1-phase-or-3-phase-inverter-What-are-the-advantages-and-disadvantages

From Practice:

In our free technical consultation, on the communication platform on our website,
it often revolves around the differences between 1 and 3-phase
inverters and the resulting consequences.

These differences are not insignificant, while 1-phase inverters are almost always compatible with low-voltage storage, 3-phase inverters almost always work only with high-voltage batteries.

1-phase inverters             Low Voltage Storage (48V)                               BMS is already built-in

3-phase inverters             High Voltage Storage                         BMS must be purchased additionally


Important: In principle, hybrid and battery inverters should only be operated with storage units for which they are also certified, and for which manufacturers have created a common protocol for each other. Otherwise, malfunctions, limitations, and potentially even security issues may occur, which are not covered by a warranty.

Differences between a 3-phase and a 1-phase inverter

  • 3-phase inverters are typically used for PV capacities of around 5.5 kWp or higher,
    as they distribute the higher power across three phases to avoid imbalance issues.
  • A 3-phase inverter distributes its power to three separate phases (L1, L2, and L3), which are present in more than 95% of German households. This allows for higher power delivery through even distribution.
  • In practice, however, unsymmetrical loads often occur, where the loads on the phases are not equal or the phase current is not balanced.
  • It is important to consider the extent to which 3-phase inverters can work unsymmetrically.
    Some 3-phase inverters can only deliver 1/3 of their total power on each phase, while some are capable of handling up to the maximum allowed imbalance of 4.6 kVA.

  • 1-phase inverters generate alternating current on one phase and are typically used for smaller solar installations up to 5 kW (4.6 kVA) output in residential homes.
    Depending on the orientation, they can support PV power of up to 5.4 kWp for south-facing installations, and even 7 kWp for east-west orientation.
  • In Germany, a 1-phase inverter is only approved for AC output power up to 4.6 kVA.
  • 1-phase hybrid/battery inverters are typically only compatible with low-voltage storage systems from specific manufacturers.

For example, the very popular Pylontech US Battery Series is only compatible with specific single-phase inverters.

Nur ein einziger Hersteller, die französische Firma Imeon Energy, hat einen dreiphasigen Wechselrichter im Programm, der mit den US2000C, US3000C, und US5000 Akkus kompatibel ist.

Hingegen gibt es einige einphasige Wechselrichter, die mit diesen US Low Volt Speichern von Pylontech kompatibel sind, die Geräte der Firma Sofa Solar, GoodWe und Solis. Only one manufacturer, the French company Imeon Energy, offers a three-phase inverter in its product range that is compatible with the US2000C, US3000C, and US5000 batteries.

On the other hand, there are some single-phase inverters that are compatible with these US Low Voltage storage systems from Pylontech, including devices from Sofa Solar, GoodWe, and Solis. Not to forget, all devices from the Dutch manufacturer Victron Energy are compatible with Pylontech US storage systems.

For this reason, we also have all these single-phase devices available in sufficient quantities from our warehouse in Schladen.

Advantages of Pylontech US storage systems:

- Low price

- Solid and durable technology

- 95% discharge capability

- Built-in Battery Management System (BMS)

In a conventional high-voltage battery, an external BMS is always required, which costs an additional 700-1000 €. Read on to learn more about the differences.

Important: Not compatible with Pylontech are all inverters from the Chinese manufacturer Growatt. There has been no common protocol for several years, so fundamentally all Growatt inverters and all Pylontech storage systems are not compatible.

What is a Phase Imbalance?

Phase imbalance

The limit for maximum phase imbalance in the power grid in Germany is 4.6 kVA. This value is defined in the VDE-AR-N 4105 (Technical Rules for the Connection of Customer Systems to Low Voltage Networks).

Advantages and Disadvantages of Low Volt and High Volt Storage Systems:
The difference between a Low-Volt (low-voltage) storage system and a high-voltage storage system is mainly in the voltage level at which they operate.

Low-Volt Storage:
A Low-Volt storage system typically operates at lower voltages, typically around 48 V, sometimes even lower. Battery modules are connected in parallel, which maintains the voltage while increasing the current. Low-voltage storage systems are typically used with single-phase inverters up to 4.6 kVA AC output power.

  • They are often more cost-effective than high-voltage storage systems since a Battery Management System (BMS) is typically already built into the storage system. It's easy to achieve when connecting storage systems in parallel.
  • Low voltages in a Low-Volt storage system can help reduce safety risks. The risk of electric shocks or injuries from touching the battery is lower than with high-voltage storage systems.

High-Voltage Storage:
A high-voltage storage system operates at higher voltages, often in the range of 200 V to several hundred volts. The battery cells are connected in series. They additionally require an external Battery Management System.
High-voltage storage systems are typically used in larger solar installations with 5 kWp or more solar module capacity.

  • Wiring high-voltage storage systems is easier due to smaller cable cross-sections, but it can also be slightly more dangerous due to higher voltages.
  • Due to the higher operating voltage and associated lower currents, high-voltage storage systems can be more efficient with smaller cable cross-sections. Larger low-voltage storage systems may require an increase in cross-sections with multiple cables, for example.
  • High-voltage storage systems are typically more expensive for smaller PV installations because the storage elements need to be connected in series, often requiring an additional external BMS (Battery Management System).

You can view our range of low-voltage storage systems at the following link:
                                 Affordable Battery Storage | inutec (inutec-int.com)

Of particular note are the BYD High-Voltage Storage Systems, which are compatible with numerous inverter manufacturers such as Kostal, GoodWe, Fronius, SMA, Sungrow