Hoymiles battery inverters (AC Coupled) are typically a retrofit for customers who already have a solar system but wish to add storage batteries to the existing system.

While battery inverters are very similar to hybrid inverters, the main difference is that a battery inverter only has a battery port, not a PV port (solar panel port).

It is also an AC coupling solution (unlike hybrid inverters, which are a DC coupling solution). This means that battery inverters convert the AC power your microinverters produce into DC power, which can then be stored in batteries. Hence the name ‘battery inverter’.

Battery inverters are mostly used for PV retrofit, either in string systems or microinverter systems.

For instance, if you already have a PV system, and want to add energy storage functionality, then you need a battery inverter to connect to your system for power backup – i.e. your battery.

It works like this:

1. Your PV inverter converts the DC power your PV modules capture into AC power.
2. Then, the battery inverter converts that AC power back into DC power, so it can be stored in the battery.
3. Home appliances run on AC power. So, when you need to drain power from your battery, then the power needs to be converted back to AC to feed the appliances properly and safely.