Photovoltaic MPPT battery charge controller using the MPT612 IC reference board Dwindling fossil fuel resources and the adverse environmental effects arising from converting these resources into energy have placed increasing focus on the use of non-fossil fuel energy sources such as solar energy.
Solar illumination can be converted into electrical energy through solar cells and the energy generated is called PhotoVoltaic (PV) energy. While the sun as a source is available for free, generating PV energy is expensive. This makes it important to extract the maximum PV energy from the incident sun light using the solar cells.
Typical solar cells comprise a PN junction made of a semiconductor material such as silicon. Since the power from a single cell is too small to be of practical use, cells are connected in series-parallel fashion to realize higher power, voltage and current. These are called solar panels or modules. PV panels are rated in terms of peak-watt at standard test conditions (25 degree C, 1000 W/m2 power density and spectrum of AirMass 1.5).
The PV power extracted can be used:
To directly power a DC load
To be converted to AC using an inverter to drive an AC load
To charge an energy storage device (battery, super capacitor etc.) enabling the power to be used on demand
This application note focuses on charging batteries from a PV panel using an
MPPT-enabled charge controller.
Typically a charge controller performs the following basic functions:
Controls maximum power extraction from a panel by tracking the MPP and ensuring that the panel operates at MPP
Controls battery charging as defined in the battery charge cycle specification to improve usable battery life and protect it against reverse connection, over charging and deep discharging
Load protection against overloads and short-circuits
LED or LCD Status indications
Communication of system parameters to external systems using dedicated interfaces MPPT充电控制器参考设计
The MPPT charge controller reference design example introduces a small, low-power MPPT IC called the MPT612, the first of its kind, supported by a patent-pending MPPT algorithm, which delivers up to 98% efficiency, and can be configured for customer-specific tasks. In this example, the charge controller takes power from solar PV panel and charges the battery as per the battery charge cycle specification. It also enables the battery to supply power to the DC loads connected to the controller. Apart from this, a number of protection mechanisms, system status indications, configurability, and communication facilities are implemented. The demo board also consists of a JTAG/UART add-on board which can be used for debugging, configuration, and data logging.