In response to global warming and greenhouse effects, energy conversion has become an extremely important subject matter in the area of global environmental sustainability. The promotion and development of renewable energy has become a focal point of economic, trade and environmental policies in many countries. Among the many present renewable energy sources, solar technology development is relatively mature. According to a marketsandresearch.biz survey, the global MPPT PV Solar Energy Charge Controller market size was estimated to be 173 million USD in 2021, however it is expected to grow to a figure of 246 million USD by 2028, showing a compound annual growth rate (CAGR) of 5.2 %.
Holtek Semiconductor is a professional MCU design company. With a focus on ESG environment sustainable development, it has recently launched its "MPPT solar charge controller" application solution. This solution has, at its core, an Arm Cortex-M 32-bit MCU as the main controller, giving it the ability to fully maximise available sunlight to electrical energy conversion efficiency to achieve superior energy storage effects.
Present day solar photovoltaic power generation systems include solar panels, controllers, batteries and related loads. In all applications, the controller adopts an extremely critical role in its management of the entire system. One important differentiation between different charge controllers is that of PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking), but it is MPPT that has the higher charging conversion efficiency. MPPT technology has the ability to maximise the solar energy conversion and store the energy in batteries. It is also responsible for controlling start and stop load switching and for implementing protection functions, etc. The selection of an MPPT solar charge controller can be evaluated from three standpoints.
Algorithms
As solar panels are affected by environmental factors such as the amount of available solar radiation and ambient temperature, the maximum output power will be dependent upon these environmental conditions. Using an MPPT algorithm to track these factors will ensure that related products operate at their maximum power point and achieve optimal energy conversion.
Mainstream MPPT algorithms normally utilise an open-circuit voltage method, short-circuit current method, disturbance observation method and conductivity incremental method. After undergoing comprehensive Holtek evaluation, it was decided to utilise a Holtek Arm Cortex-M0+ HT32 MCU at the core of the design for the solar controller using the MPPT disturbance observation method. This method changes the voltage to observe the present real time power, and then compares it with changes in the recent before/after two power values to adjust the voltage magnitude of the next cycle in real time. Repeating this process will ensure that the energy conversion operates at its maximum power point to achieve optimal battery charging.
This solution can achieve MPPT efficiencies in excess of 99%, reaching beyond the expectations of present market products.
MCU types
Holtek has a comprehensive range of 32-bit MCUs allowing customers to choose the most cost-effective MCU device for their MPPT solar charge controller according to their product type, function and HMI requirements.
The MCU includes a wide array of significant integrated peripheral IPs. For PMOS/NMOS driving, there are complementary PWM output functions, which have a programmable dead-time generator providing improved safer operation of the charging/discharging circuit. There are integrated OPAs, which can be used for noise filter circuit design and for current and voltage sampling amplification to improve measurement accuracy. Also integrated are comparator and DAC functions, which are used to implement overcurrent, overvoltage and other protection features.
The HT32 MCUs have passed UL/IEC 60730-1 Class B software certification and can therefore provide relevant and complete self-test procedures.
Conversion efficiency and management functions
The MPPT solar charge controller is designed using a HT32 microcontroller which includes Constant Current and Constant Voltage charging as well as tracking transient maximum power charging.
The high-frequency DC-DC conversion charging/discharging circuit can effectively reduce energy loss, greatly improve charging efficiency, being able to provide conversion efficiencies as high as 92%.
The MCU main controller manages the charging/discharging process intelligently and is therefore able to reduce the risk of battery damage as well as extending battery life.
As an overall evaluation, this solution includes the advantages of automatic battery voltage measurement, smart charging, high MPPT tracking efficiency and high charging conversion efficiency as well as having a comprehensive set of protection features. This range of features combine to make it highly suitable for various battery types to meet the needs of a wide range of related products.
HOLTEK not only provides MPPT solar charge controller solutions using its 32-bit MCU design that can be quickly introduced into volume production, but additionally its highly experienced design team can modify and optimise the customer's MPPT charging technology applications according to the inherent characteristics of the customer's energy storage battery. If customers decide to also use the Holtek application specific Inverter MCU HT45F5V, this carries the possibility of expanding the application product's function to incorporate multi-functional solar inverter energy storage box features.
HOLTEK HT32 MPPT solar energy charger solution
