The MPPT technology optimizes solar charging efficiency, enabling faster charging, increased energy output, and extended battery life while ensuring safe and reliable power management.
A Maximum Power Point Tracking (MPPT) based solar battery charger plays a vital role in optimizing the efficiency and performance of solar energy systems. By continuously adjusting the charge controller to operate the solar panel at its maximum power point, MPPT ensures that the system captures the most energy possible, even under varying environmental conditions like changes in sunlight or temperature. This results in faster charging, increased energy output, and extended battery life. The Renesas ISL81601-US011REFZ solar battery charger board with MPPT reference design uses energy from a user-provided solar panel to charge a 12V lead-acid battery.
The MPPT software optimizes power from the solar panel, while the RL78/G14 microcontroller (MCU) manages the output voltage, ensuring a safe charging profile for the battery. The reference boards are designed to simplify creating a solar battery charger. They integrate the buck-boost controller, MCU, linear regulator, and quad operational amplifier.
Key features of the reference design include support for up to 40VIN and 60VOUT, capable of delivering over 10A of output. The output is programmable to match battery requirements up to 60V, currently optimized for a 12V, 8Ah lead-acid battery. It automatically switches to float mode to maintain the battery after a full charge. Maximum power point tracking in software optimizes the power drawn from the solar panel, and integrated protection features include overcurrent, overtemperature, over/under voltage, and reverse polarity protection.
The design uses the ISL81601 buck-boost controller to convert voltage from an external solar panel to the appropriate level for charging a 12V lead-acid battery. The MCU collects telemetry data and manages the controller to follow the battery charging algorithm. The MCU is powered by the ISL80410 linear low dropout regulator (LDO), while the ISL28413 quad op-amp buffers and amplifies signals between the buck-boost controller and the MCU. The ISL28022 digital power monitor can be added as an optional component for systems requiring higher precision current measurements.
The board operates with an input voltage range of 8V to 40V, designed to accommodate most standard solar panels. The 8V and 40V limits are set to provide undervoltage lockout protection and ensure the maximum voltage on the linear regulator is not exceeded.
The system offers several benefits, including an MPPT algorithm that maximizes power usage from the solar panel and a buck-boost architecture that allows the battery to be charged even when the solar panel’s voltage is lower than the battery’s voltage. It also features programmable charge rates, supporting modes like fast-charge and trickle-charge, and supports input voltages up to 60V with an adjustable output voltage range from 0.8V to 60V. Additionally, the system monitors battery status and provides protection against damage caused by overcharging.
Renesas has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.
