plate limits of the PV input must be strictly followed.
To get the optimum Voltage, the solar modules shall be connected in series to form a string having
the desired voltage. The optimum operating voltage of the module string (Vmpp) must always be
above the battery Voltage.
To establish the minimum number of PV modules to be connected in series in the same string,
the max voltage of the battery must be multiplied by 1.1 and divided by the modules Vmpp
voltage.
or example, for a 24V system with a lead-acid battery with maximum Voltage of 30 V and using
PV panels with 17V Vmpp. 30*1.1/17=1.94.
The result must be rounded up to the higher value (i.e. 2 modules - of 17 Vmpp - in series for the
above example is the MINIMUM number of panels required for operation).
Maximum Panels in Series
The open-circuit voltage of the string must be lower than 90V under any temperature and
irradiation conditions. To establish the
maximum numbers of the P
modules connected in series in the
same string, use the following
formula: 90V/(Voc). (Example: 90/
(22)=4.09). The result must be
rounded down to the lower value (i.e. 4
modules - of 22 Voc - in series for the
above example).
There can be thus 4 PV modules in
series of the mentioned model for a
24V system as per this example.
Table 2 gives an idea of the possible
arrangements for common panels
according to the number of cells or
their type. Note that CIS or other forms of THIN film PV modules cannot be connected to REhub
unless their Voc is <90V.
5.4 Parallel connection o Solar PV string
To get the required charging power, 2 or more strings are usually to be connected in parallel. Each
string connected in parallel must be composed by the same number of modules of the same type.
The number of strings connected in parallel depends on the Isc of each string. When you need to
determine the Isc of the parallel array, it is the Isc of each panel multiplied by the number of
parallel strings. or example, if the Isc of the panels used in the system is 4A. And the number of
Parallel strings is 4, then the Isc of the array is =16A.
The total power of the array can be slightly higher than rated power of REhub. This excess capacity
is designed in to get the desired charging power under all circumstances of Solar radiation.
However, the output current from REhub will be limited to the maximum rated current.(This is 25A
in REhub-12/24-25 models)
5.5 Cable Size
Based on Array arrangement, calculate INPUT current. Choose the appropriate cable size for INPUT
current based on the length of the cable from the PV panels to REhub. REhub must be located
close to the Batteries. Connect the PV +Ve to Terminal [2] and connect PV -Ve to Terminal [1].
5.6 Battery Connection
There are two connections to the batteries from REhub. Connections [3- Battery +ve] and [4 –
Battery -Ve] deliver the Solar charge to the batteries. Keep the Inverter in switched off / Away
mode till you are ready with all connections. Do not close the Battery connections till you are ready
6
V3 0 User Manual`
