Renogy MPPT Series, Руководство пользователя

Страница: 11 / 29

10
4. Operation
4.1 MPPT Technology
The MPPT40CC utilizes Maximum Power Point Tracking technology to extract
maximum power from the solar module(s). The tracking algorithm is fully
automatic and does not require user adjustment. MPPT technology will track the
array’s maximum power point voltage (Vmp) as it varies with weather conditions,
ensuring that the maximum power is harvested from the array throughout the
course of the day.
Current Boost
In many cases, MPPT40CC MPPT technology will boost the solar charge
current. For example, a system may have 8 Amps of solar current flowing into the
charge controller and 10 Amps of charge current flowing out to the battery. The
MPPT40CC does not create current! Rest assured that the power into the charge
controller is the same as the power out of the MPPT40CC. Since power is the
product of voltage and current (Volts
× Amps), the following is true*:
•
Power Into the controller = Power Out of the controller
•
Volts In × Amps In = Volts Out × Amps Out
*Assuming 100% efficiency. Actually, the losses in wiring and conversion exist. If
the solar module’s Vmp is greater than the battery voltage, it follows that the
battery current must be proportionally greater than the solar input current so that
input and output power are balanced.
The greater the difference between the
maximum power voltage and the battery voltage, the greater the current
boost
. Current boost can be substantial in systems where the solar array is of a
higher nominal voltage than the battery.
An Advantage Over Traditional Controllers
Traditional controllers connect the solar module directly to the battery when
recharging. This requires that the solar module operate in a voltage range that is
below the module’s Vmp. In a 12V system for example, the battery voltage may
range from 11-15Vdc but the module’s Vmp is typically around 16 or 17V.Figure
4-1 shows a typical current vs. voltage output curve for a nominal 12V off-grid
module.