ROGUE MPT-3024, Инструкция по установке и руководство пользователя

Страница: 14 / 52

14
4.6 Match the modules of an array
Although the individual PV modules of an array need not necessarily be of the
same make or model, you will achieve better tracking performance from an
array in which all of the modules have the same maximum power point (V
mp
).
This is best accomplished by choosing modules of the same make and model.
Even if modules are not identical, be sure that they each have the same
number of cells. While it is possible to wire modules together with varying
numbers of cells, this will degrade the output of the entire array.
5. Lead-Acid Battery Charging
5.1 Charging basics
It’s possible to charge a lead-acid battery by any one of several different
methods. Low-end chargers are typically on/off devices, where the charger
cycles between full on and full off depending on the terminal voltage of the
battery. These chargers may over- or undercharge a battery and provide no
means of maintaining a battery’s state once it has been completely charged.
More advanced chargers utilize a multi-stage approach that closely monitors
the battery’s voltage and the current being drawn by the battery during the
charging process. These chargers select a charging mode which best suits the
condition of the battery at any given time, resulting in optimal charging, less
maintenance, and extended battery life.
A lead-acid battery which is discharged generally begins charging at a rate
equal to its capacity in amp-hours divided by a value of five to twenty (C/5 to
C/20). C/10 is a good rate, which allows for fairly rapid, well-controlled
charging. A charger operating at this rate is in the BULK mode. A charge
controller operating from a PV array that is properly matched to its battery
bank seldom produces more than the C/10 rate, so it will usually charge a
battery in the bulk mode with all available power from the PV array.
A multi-stage charge controller will constantly monitor the terminal voltage at
the batteries during the BULK mode. The battery will be considered nearly full
once it reaches its absorption voltage (which is around 14.3 - 14.7 volts for
most lead-acid batteries). At this voltage, the BULK mode will terminate and the
charger will begin charging the battery at a constant voltage equal to its