11 Glossary
SMA Solar Technology AG
66
SI80H-BE-BEN120810
Operating Manual
11 Glossary
Absorption phase
See constant voltage phase
AC coupling
The connection between various loads, generators and storage devices in the stand-alone grid.
AGM battery
Absorbent glass mat separator battery. In AGM batteries, the electrolyte is held in a fibreglass mat.
The AGM battery is a sealed lead acid battery. A gas mixture consisting of hydrogen and oxygen is
always generated when lead acid batteries are charged, and in normal operation this mixture
undergoes internal recombination to form water. Hence, there is no need to regularly top up the
battery cells with water, which is why these batteries are often described as low maintenance or even
maintenance-free batteries. AGM batteries are available from many different manufacturers for a
wide range of applications. They usually have very good high-current properties but lower deep-cycle
stability.
Anti-islanding
Anti-islanding is a process which protects against unintentional stand-alone grid formation at the
connection of the external energy source. This is required to ensure that the off-grid inverter prevents
possible reverse voltage to these power supply units if the external energy source fails.
Battery
A battery is an electrochemical energy storage device that can release previously stored chemical
energy as electrical energy. A distinction is made between non-rechargeable primary elements and
rechargeable secondary elements (rechargeable batteries or accumulators). Lead acid batteries are
generally used as rechargeable secondary elements in off-grid systems.
Battery bank
See Battery system
Battery charge mode
An off-grid inverter operating mode, in which the off-grid inverter takes energy from the AC grid to
recharge the battery in a controlled way. In this operating mode, the off-grid inverter is primarily
responsible for correctly charging the batteries and acts like an independent battery charging device.
