SMA SUNNY ISLAND 4548-US Operating Manual page 239

SMA Solar Technology America LLC 23 Glossary
Split-Phase
A split-phase system is a three-conductor single-phase distribution system, commonly used in North
America, the UK, Australia and New Zealand for single-family residential and light commercial
applications up to 100 kVA. Its primary advantage is that it saves conductor material since a
single-phase system with one neutral conductor is used, while on the supply side of the grid
configuration only one line conductor is necessary. Since there are two live conductors in the system,
it is sometimes incorrectly referred to as "two-phase system". To avoid confusion with split-phase
applications, it would be correct to call this power distribution system a three-conductor, single-phase,
mid-point, neutral system.
String
Describes a group of electrical series-connected PV modules. A PV system usually consists of a number
of strings, which avoids yield losses due to variations in shading over different modules.
String Inverter
Inverter concept in which the disadvantages of the central inverter concept are avoided. The PV is split
into individual strings, each of which is connected to the external transmission line with its own string
inverter. This greatly simplifies installation and greatly reduces the yield losses caused by
manufacturing deviations or variations in shading of the PV modules.
Overload Capacity
The overload capacity of an inverter describes its ability to supply short-term (seconds or minutes)
excessive loads that can be significantly higher than the nominal power of battery inverters. The
overload capacity is necessary in order to be able to also start electronic machines that have a
nominal power similar to the nominal power of the inverter in the stand-alone grid, since these
machines typically need six times more current during start up in relation to the nominal current.
Full Charge
Recharging of the batteries to a level of approximately 95% on a regular basis (at least once a
month). This efficiently avoids premature aging of the batteries caused by inadequate charging.
VRLA
Valve Regulated Lead Acid battery: lead-acid battery with immobilized electrolyte or flooded lead–
acid battery. Examples of this type of battery are SLA batteries and AGM batteries (Absorbent Glass
Mat).
Inverter
A device for converting the direct current (DC) from the PV array into alternating current (AC), which
is necessary for the connection of most devices and especially for the feed-in of solar energy into an
existing transmission line. Inverters for PV systems usually include one or more MPP trackers, store
operating data and monitor the grid connections of the PV system.
Operating Manual SI4548-6048-US-BE-en-21 239