What is Maximum Power Point Tracking (MPPT)?
Solar power is an abundant and renewable source of energy. Every square meter of Earth receives about 342 watts of solar energy on average over a year. This energy is enormous; specifically, 44 quadrillion (4.4 x) watts of energy. Solar photovoltaic (PV) systems use a variety of technologies and methods to achieve their full potential. Maximum PowerPoint Tracking (MPPT) is one such method. To maximize the energy production of a photovoltaic (PV) system, MPPT is an essential technique utilized in solar inverters. It’s important because a solar panel’s ability to produce power changes depending on temperature, shade, and sunlight intensity. The operation of MPPT and its importance are as follows:
Basic settings for the MPPT solar charge controller
MPPT Working Steps
The Maximum Power Point (MPP) concept
Every solar panel has an optimal position for operation where it generates the most power. The term Maximum Power Point (MPP) is used to describe it. Charge controllers employ the Maximum Power Point Tracking (MPPT) approach to get the maximum power from PV modules under specific circumstances. This point is impacted by several variables, including temperature and light intensity. When measured at a cell temperature of 25°C, the maximum power voltage of a typical PV module is approximately 17 V; however, on extremely hot or extremely cold days, this voltage can vary, dropping to around 15 V or rising to 18 V.
Maximum power point (MPP) curve
The IV Curve
The electrical properties of a solar panel can be shown on a graph known as an IV curve. It indicates the relationship between the panel’s produced current (I) and voltage (V).
To determine the MPP, an MPPT controller constantly analyzes the solar panel’s IV curve by changing the operational point.
When PV modules are exposed to irradiation of 1000 W/m², the I-V curves indicate their maximum power output.
Incremental Perturb and Observe (P&O)
Solar radiation from the sun and the temperature of the atmosphere are two factors that constantly affect the output power of PV arrays. The perturbation and observation (P&O) methodology is included in some MPPT methods4. This is a standard algorithm utilized by MPPT controllers. They involve changing the solar panel’s operating point and measuring the resulting power. The controller then decides if the power increased or decreased and makes the necessary modifications.
Flowchart for the P&O MPPT method
Tracking the MPP
As soon as the MPP has been determined the MPPT controller locks onto it and makes sure the panel is operational. The MPPT algorithm determines the power output of the solar panels at different voltages based on the observed data. The voltage corresponding to the highest power output (MPP) is then determined by comparing these power outputs.
Different Types of MPPT
There are three major types of MPPT. These are given below:
1. Perturb and Observe (P&O)
The MPP is tracked using P&O. Due to variations in PV module power; this method tracks the MPP of a PV system in a mirror scale. The output power can be compared to the prior output power while measuring it, and it is periodically monitored.
Flow chart of P&O algorithm
2. Incremental Conductance
A typical solar panel converts 30–40% of solar radiation into electrical energy. MPP increases the solar power system’s efficiency. According to maximum power transfer, the power output is at its highest when the circuit’s impedance and the load’s impedance are in balance. The operational point for the information voltage and current source is found using the Incremental Conductance (IC) method. This method is similarly based on the slope of the solar power curve relative to the voltage curve at zero MPP.
Incremental Conductance algorithm flowchart
3. Current-based MPPT
To measure the MPP, this method requires both current and voltage. Only the PV module’s current value is required for this procedure. Use a DC-DC boost converter for this method to transfer energy between the battery and the PV panel7.
Importance of MPPT
- System Efficiency
· MPPT makes sure the inverter efficiently transforms solar energy captured from the sun into useful power by working at the MPP. Enhanced power conversion results in better.
· The total efficiency of a solar power system is increased through MPPT. The solar panels would frequently run below its MPP without MPPT, resulting in lower efficiency.
- Maximizing Energy Harvest
· The main goal of MPPT is to obtain as much power as possible from solar panels under a variety of circumstances. This results in more energy being produced.
· Even in less-than-ideal situations, MPPT enables inverters to harvest the maximum amount of electricity possible from solar panels. As a result, the system as a whole performs better and produces more energy. According to research, MPPT showed higher tracking efficiency (>99%), faster convergence to the global peak with little time (0.1s), and negligible fluctuations around MPP, allowing it to capture the greatest amount of energy from the PV system 6.
Image source: Sarah Lozanova
- Increased ROI
The ability to maximize energy harvest makes MPPT a vital element in both commercial and residential installations since it increases the return on investment for a solar power system.
- Decrease Component Stress
As they receive the most reliable and effective power while operating at the MPP, inverters and batteries are less stressed as a result of other system components.
Modern solar power systems need to use MPPT technology. It makes sure that solar panels work as efficiently as possible, enhancing the amount of energy captured and increasing solar energy’s economic viability as a renewable resource.