Technical Structure Of The Stecagrid; General; Master-Slave Principle; Cooling - Steca StecaGrid 2000+ D Master Instructions D'installation Et De Service

3 Technical structure of the StecaGrid

3.1 General

The StecaGrid is an inverter that uses a transformer to galvanically isolate solar
modules from the mains grid, etc. The inverter was designed so that it can be
installed outside without any problems (IP65).
The StecaGrid is controlled by microcontrollers. The microcontrollers set the volt-
age of the solar modules in such a way that the solar modules provide their max-
imum output (maximum power point tracking). Both inputs have their own MPP
tracker which allows you to design your system flexibly. For example, you can
connect the modules with a south-east orientation to Input 1 and the modules
with a south-west orientation to Input  without any mismatches and therefore
any loss in yield. Furthermore, it is possible to connect type-A modules to Input 1
and type-B modules to Input  without any mismatch occurring.
The input voltage range was selected in such a way that the rated voltage range
of the PV modules is covered from 80 V - 410 V (open circuit voltage max. 450
V). The maximum input current that the inverter can process is 8 A per input.
When both inverter inputs are connected in parallel the inverter can process cur-
rents up to 16 A. The MPP tracker ensures that the input currents never exceed
the maximum permitted current.
At night, the inverter keeps its use of the electronic components and electricity
consumption to a minimum by switching to sleep mode. The inverter is protect-
ed against stand-alone operation.
3.2 Master-slave principle
The StecaGrid works according to the master-slave principle. With this principle,
several functions are combined in the master (inverter A in the diagram).
The inverters without these functions are referred to as slave inverters (inverters
B and C in the diagram). The regional settings are made via the master.
An MSD function is regulated for all the inverters via the master. The master
also stores data from the master inverter and the slave inverters, etc. Because
the functions are combined centrally, slave inverters can be realised more cost-
effective and more compact.  StecaGrid Slave inverters can be connected to
each StecaGrid Master inverter. Any type of StecaGrid Master inverter can be
combined with any type of StecaGrid Slave inverter (a maximum of two slaves
per master is possible). The combination of master and slave devices allows the
dimensioning to be as flexible as possible: System sizes between 1600 Wp and
7000 Wp are possible using master-slave combinations.* For system sizes greater
than 7000 Wp several master-slave combinations can be used.
* with a sizing ratio between 0.8 and 1.5 and assuming that the system voltage and system current are within the
operating range of the inverter.
See www.stecasolar.com for a dimensioning software.

3.3 Cooling

The inverter transfers its heat via a cooling element. Because of the large surface
area of the cooling profile the inverter can operate in ambient temperatures
between –5 °C and +60 °C.
WARNING
Risk from hotness!
The surface temperature of the aluminium cover may exceed 70 °C.

An integrated temperature control prevents excessive internal temperatures.
When the ambient temperature exceeds the (derating) limit, the highest value
of the power consumption from the PV modules is automatically adjusted to
the prevailing temperatures. This process reduces the heat transfer from the
inverter and prevents the operating temperature from becoming too high. When
the ambient temperature is above +40 °C, maximum output can be restricted.
StecaGrid inverters do without a ventilator for cooling and are therefore particu-
larly low-maintenance.
6
EN
Master
X
X) Control unit
A) Inverter A
B) Inverter B
C) Inverter C
731.614 | 10.04
Slave Slave
A B C