Glossary
SMA
Solar Technology AG
202
SI2012_2224-TEN082311
Technical Description
22 Glossary
Absorption Phase
Constant V phase: a charging phase using constant charging voltage. The charging current
constantly decreases during this phase.
AC
Abbreviation for "Alternating Current".
AC Coupling
The connection of various loads, generators and storage devices on the AC side.
AGM Battery
Absorbent Glass Mat separator battery. This is a battery where the electrolyte (a mixture of water
and sulfuric acid) is bound to a fiberglass mat. This is a type of so-called closed lead acid battery.
A gas mixture (hydrogen and oxygen) is always generated when lead acid batteries are charged,
and in normal operation this is internally recombined to form water. This removes the need for
regularly refilling the battery cells with water, which is why these batteries are often described as
“low maintenance” or even “maintenance free”. AGM batteries are available from many different
manufacturers for a wide range of applications. They usually have very good high current
properties but are not very charge-cycle resistant.
Ah
Abbreviation for “ampere hours”: unit of electrical charge; one ampere hour is the charge provided
by a constant current of 1 A over a period of one hour - when two separate charges are connected.
Anti-Islanding
Anti-Islanding is a procedure for preventing unintended islanding on the generator and/or external
grid connection point. It is required in order to ensure that, in case of a public grid dropout or
generator failure, the Sunny Island reliably prevents possible reverse voltages in these power supply
units.
Automatic Disconnection Device
The “automatic disconnection device between a grid-parallel, power-generating system and the
public low voltage grid” (DIN VDE 0126-1-1) is an equivalent replacement for a normal public
disconnection device with isolation function which is accessible to the distribution grid operator at
any time. This is a mandatory safety device which prevents energy from a solar power system being
fed into an external power grid when the external power generator is not functioning. In the Sunny
Boy / Sunny Mini Central, this function is performed by the "SMA grid guard Version 2". In the case
of the Sunny Backup 2200 and Sunny Backup 5000 it is integrated in the Automatic Switch Box.
