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Chapter 1 Installation
1.1 Loads Requirement
The OPTI-Solar SC MPPT Series series plays a major role in planning your PV
system. The first step in planning an efficient PV system is to calculate the load
requirement. In order to calculate the anticipated load requirement, it is important to
determine average and peak load consumption. The possible load growth should also
be taken into consideration when planning the load requirement because loads
hardly remain static and they grow more frequently than they reduce.
1.2 Battery Voltage System
After the estimate of the power requirement, the required power from the battery
will be the next consideration in planning the system. According to the basic rule of
the electricity, "Current is the power divided by voltage", when the power amount
increases, it is suggested to raise the battery voltage so the current amount will
decrease. The principle is based on the larger amount of current is, the more expen-
sive the circuit protection is. In an example of the 96 watt load, it draws 4 amps at
24V battery system but it draws only 2 amps at 48V system.
1.3 PV Array Voltage
As the OPTI-Solar SC MPPT Series is a smart DC to DC converter design, the
specification of a PV array is much like sizing a grid tie inverter. Installers choose
the max. and min. Vmp and Voc of each string and how many strings are needed.
1.4 Maximum Voc
The maximum operating voltage of the SC-50 MPPT and SC-80 MPPT is 140 Vdc
and of the SC-80X MPPT and SC-160X MPPT is 240Vdc. The protection will be
active to shut down the unit when the operating voltage is higher. PV array manu-
facturers has the published data sheet with rated voltage and current as well as the
current and temperature coefficients. The rated Voc is measured in the temperature
of 25 so when calculated at lower temperature such as 0 , 25% increase of the
rated Voc is expected. At different temperature location of installation, the maxi-
mum Voc of the module should be determined by the Voc voltage temperature
coefficient and after that, a series string voltage may be determined as well.
1-1
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