Quick Answer
String inverters can be used with lithium batteries, but it's essential to consider the compatibility and efficiency of the system.
Compatibility Considerations
String inverters typically have a fixed output voltage, which can be a limitation when paired with lithium batteries that have a variable output voltage. To overcome this, some string inverters offer adjustable output voltage settings or have a built-in maximum power point tracking (MPPT) algorithm that can adapt to the changing voltage of the lithium battery. For example, the Fronius Symo inverter has an adjustable output voltage setting that allows it to work with lithium batteries.
Efficiency and Charging Modes
When using string inverters with lithium batteries, it’s crucial to select an inverter that supports charging modes specifically designed for lithium-ion batteries. For instance, the SMA Sunny Boy inverter offers a “Lithium Charging Mode” that ensures the battery is charged efficiently and safely. This mode prevents overcharging, which can reduce the lifespan of the lithium battery. When choosing a string inverter for lithium battery applications, look for features like MPPT, adjustable output voltage, and lithium-specific charging modes to ensure optimal performance and efficiency.
Choosing the Right String Inverter
When selecting a string inverter for a lithium battery system, consider the inverter’s power handling capacity, efficiency, and compatibility with the battery management system (BMS). For example, the OutBack VFX inverter series has a high efficiency rating (up to 96%) and supports a wide range of battery types, including lithium-ion. Ensure the inverter is designed to handle the maximum power point of the solar array and the lithium battery’s discharge characteristics.
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