AIMS Power MPPT+ Series, Инструкция по установке и эксплуатации

Страница: 7 / 51

Chapter 1 Installation
1.1 Load Requirement
The AIMS MPPT+ 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 that
exists, the more expensive 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. Cable size thus also decreased as
current is decreased. It is another reason to up the Voltage in larger systems.
1.3 PV Array Voltage
As the AIMS MPPT+ 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 SCC40MPPT and SCC80MPPT is 240Vdc. The protection will
be active to shut down the unit when the operating voltage is higher. PV array manufacturers have 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 temperatures dependent on location, the
maximum 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.