Energy Storage - Fronius
A battery storage system, also known as an electricity storage system or energy storage system, stores the surplus solar power generated by the PV system during the day that exceeds the household’s consumption. The range includes battery modules and ready-to-use storage sets from 5 to 30 kWh for hybrid inverters, plug-and-play storage systems for balcony power plants and the appropriate accessories from Growatt, Solplanet, Fronius, EcoFlow, Trina, Anker and SAJ.
Three types of battery storage systems
Which design is suitable depends primarily on the system to which the storage unit is being added.
| Type | In the range | Capacity per module | Suitable for |
|---|---|---|---|
| High-voltage modular storage | Growatt APX and ARK, Solplanet Ai-HB, Fronius Reserva, Trina, EcoFlow Ocean 2 | 2.56 to 5 kWh | Roof-mounted system with hybrid inverter |
| Low-voltage module storage | Growatt AXE, Solplanet Ai-LB | 5 to 5.12 kWh | Roof-mounted system with hybrid inverter |
| Plug-in storage system | Growatt NOAH 2000 and NEXA 2000, Anker SOLIX Solarbank 3 E2700 Pro, EcoFlow DELTA 2 | 1 to 2.7 kWh | balcony power plant |
Modular storage systems for rooftop installations are stacked into a tower using several battery modules and never operate on their own, but always in conjunction with a hybrid inverter that controls charging and discharging. They can be found under Storage for inverters, partly as individual modules and partly as ready-to-use sets with a control unit. Plug-and-play storage units combine the battery and control system in a single housing and are installed between the modules and the grid feed-in. They can be found under Storage for balcony power plants.
High-voltage or low-voltage
In a high-voltage storage system, the modules are connected in series; the voltage of the stack increases with each module added. In most systems, this includes a dedicated BMS unit – the battery management system – which monitors the cells and the charge state. A low-voltage storage system operates at around 50 V and is expanded by adding modules in parallel. The Growatt AXE features its BMS integrated into the module, is protected in accordance with IP20 and must therefore be installed in a dry indoor location.
In practice, the choice of design is determined by the inverter: it is designed for a specific voltage range and for certain storage systems.
Which storage system is compatible with which inverter
A storage system will only work with an inverter for which the manufacturer has approved it. The inverter’s list of compatible storage systems is decisive. For these devices in the range, the manufacturers’ lists specify:
- Growatt MOD HU: exclusively the APX storage system
- Growatt MOD XH: ARK, APX, AXE and ARK LV
- Growatt MIN XH: ARK and APX
- Solplanet ASW H-T2 and H-T3: Ai-HB only
For all other combinations, the storage list in the hybrid inverter’s data sheet applies. If a storage unit is not listed there, the combination is not approved. Matched combinations are available as storage-inverter sets.
How large the storage system should be
The key factor is consumption after sunset and in the early morning, as this is the only consumption the storage system can cover. A storage system that is significantly larger will not be fully charged on many days. As module-based storage systems increase in capacity in fixed increments, you can start small and upgrade later: for Growatt ARK, Solplanet Ai-HB and Trina in increments of 2.56 kWh; for Fronius Reserva from 3.15 kWh; and for Growatt APX and EcoFlow Ocean 2 from around 5 kWh. The upper limit per system is specified in the data sheet, for example 20.48 kWh for Solplanet Ai-HB G2 Pro, 25.6 kWh for Growatt ARK and 30 kWh for Growatt APX.
What matters in the data sheet
The usable capacity is slightly below the rated capacity; for the Growatt ARK module, for example, it is 2.3 out of 2.56 kWh. According to the data sheet, all batteries in the range use lithium iron phosphate (LFP). The number of charge cycles ranges from 3,000 for the EcoFlow DELTA 2 to 10,000 for the EcoFlow Ocean 2; most modules specify 6,000. The manufacturer’s warranty is generally ten years, five years for the EcoFlow DELTA 2 and fifteen years for the Ocean 2 module. The temperature range specified in the data sheet determines whether a garage or cellar is a suitable installation location.
Bases, distribution units and connection parts can be found in the accessories for battery storage systems, whilst complete systems with storage are listed under Complete PV kits with storage.
For photovoltaic systems and their essential components, no value added tax is charged where the conditions of Section 12 (3) of the German VAT Act (UStG) are met. You state during the ordering process whether they apply to you.
Frequently asked questions about battery storage
Is an electricity storage system the same as a battery storage system?
Yes. Electricity storage, battery storage, solar storage and energy storage all mean the same thing in a domestic context: a battery that stores solar power for later use.
How big should my battery storage system be?
Large enough to cover your consumption from the evening until the following morning. As the modular storage systems are expandable, you can start with a smaller size; the system’s upper limit is specified in the data sheet.
Can I retrofit a storage system?
With a hybrid inverter, yes, provided the storage unit is on the manufacturer’s list. If the system has a grid-tied inverter, an additional device is required, such as the Growatt SPA or the EcoFlow PowerOcean DC Fit converter. A balcony power plant can be supplemented with a plug-and-play storage unit.
Is every battery compatible with every inverter?
No. Voltage specifications and communication protocols depend on the manufacturer, and only approved combinations will work. These are listed in the inverter’s storage unit compatibility list.
Where should I install the storage unit?
Most modules are protected in accordance with IP65 or IP66. Whether the location is suitable depends on the temperature range specified in the data sheet; for the Growatt APX, for example, this is −10 to +50 °C. The Growatt AXE with IP20 should be installed in a dry indoor location.
How long does a battery storage system last?
The data sheets specify 3,000 to 10,000 charge cycles; most modules offer 6,000. The manufacturer’s warranty ranges from five to fifteen years depending on the system, usually ten.