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Maximum Power Point Tracking: Understanding the Basics

A PV panel and PV array are great systems to have to do your duty to the environment as well as save money. MPPT charge controllers are a beneficial part of any system. They can increase the efficiency of your system, as well as help to manage the resistance and voltage of the system. 

Unfortunately, one of the characteristics of voltage is that as the temperature changes, so too does the resistance and voltage. This can cause a problem when you are trying to use inverters to change to AC power, store energy in a battery bank, or send power to the grid. An MPPT controller is there to help account for any power curve.

What is Maximum Power Point Tracking (MPPT)?

MPPT, also known as Maximum Power Point Tracking, is an operation that is used in charge controllers. It converts DC (direct current) power to DC power to make sure the current and energy match up between the solar panels and any battery bank or utility grid where the power is being sent. 

Usually, the electricity from solar panels is at a higher voltage than other systems can use. So the MPPT system helps to change the direct current to a lower level that other systems can use via a smart system and inductance.  

testing solar panels

These are commonly used with a solar panel array, or photovoltaic cells, but can also be used with wind turbines and thermophotovoltaic systems. 

This not only allows the solar system to run properly but also allows for more efficient and consistent output. 

Understanding How Maximum Power Point Tracking Charge Controllers Work

Essentially, the MPPT charge controller module works by looking at the output of the solar panels and compares it to the battery voltage, or the grid it is being sent to. 

The MPPT charge controller is continually reading the input of power from the solar modules and making adjustments the keep the power output voltage at a consistent level the rest of the parts on the PV system can use.

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Pulse Width Modulation Vs. MPPT Charge Controllers

Pulse Width Modulation (PWM) and MPPT charge controllers have a key difference or two that may make one have better applications based on the conditions and energy production of your system. 

Both work to bring the charge closer to the battery’s maximum capacitance and monitor the battery’s temperature to prevent overheating. 

MPPT charge controllers are better designed to work in any cold temperature. Usually, the voltage increases the colder it is, and MPPT charge controllers can adjust to this higher voltage, whereas PWM cannot. 

However, PWM systems can adjust to any solar array size, and it is less expensive than an MPPT controller. Additionally, MPPT controllers aren’t as effective with systems that have a lower load and speed. 

MPPT essentially pulls out the power at the maximum power voltage that works best for the system and usually provides you a bit more energy, whereas PWM controllers just draw it out above battery voltage, without considering the efficiency or frequency. 

How a Maximum Power Point Tracker Works With Batteries

With batteries, MPPT controllers will adjust the voltage based on the series and advantages that work best with the battery. It will figure out the best voltage operating point for the battery and find a way to adjust the voltage values to best suit the battery while still maximizing the product or the energy. It uses various methods to adjust the amount of power going through the circuit. 

When Are Mppt Charge Controllers Necessary?

It is necessary to use an MPPT charge controller for off-grid systems or when you want a battery backup. Without using an MPPT charge controller as a converter, the voltage could damage the battery and other software with the output power. 

Solar systems rely on the sun to create energy. This energy fluctuates in a general cycle as the amount of sun and the temperatures fluctuate throughout the day. 

solar panels

You don’t necessarily have to use an MPPT, as a PWM is effective in some situations, but if you have the money, any MPPT model can make your system more effective. However, if you are just using a small system, PWM is probably better. 

MPPT Tracking

Powerful Curves

MPPT tracking is the different types of algorithms that MPPT systems use to adjust to different conditions. The voltage works like a hose.

The more water released in a flow, the less pressure at the end. But if you block the entrance, you get higher pressure. MPPT charge controllers are meant to take these various pressures, or voltage, and adjust as needed to get a more consistent and efficient flow. 

Constant Voltage

For this method of tracking, the output voltage is regulated to a constant amount. This is more common with PWM systems, as not much else is taken into account. There is no attempt to track the maximum power point and efficiency isn’t maximized. 

Incremental Conductance

This method is done to predict a voltage change. It can track changes faster than other methods and there is no oscillation of power. 

This is the most efficient, but also the most hardware intensive. 

Perturb And Observe

This is also known as the hill-climbing method as it adjusts based on the rise of the curve of power. It is easy to implement and is the most common method used. Essentially, it does small tests to see how certain voltages change the power until the right level is found. 

The efficiency still isn’t always maximized, due to the oscillation around the correct power, instead of focusing on it. 

FAQ

What are the different types of maximum power point tracking algorithms?

The most common ones are Perturb and Observe (P&O), Incremental Conductance (INC), consistent voltage, constant current, and parasitic capacitance.

What are the tradeoffs associated with different maximum power point tracking algorithms?

Usually, the tradeoffs are efficiency and power vs hardware and cost. MPPT controllers that are more accurate need constant adjustments, which takes power, computations, and a sophisticated system. This is expensive and usually requires more upgrades. Additionally, the more efficient systems can be erratic due to constantly changing conditions sometimes. 

How does the maximum power point tracking algorithm affect the overall system performance?

The better and adjustment-heavy the algorithm, the more efficient a system you get. This means you get more power from the same system. 

What are the design considerations for maximum power point tracking?

The design considerations are usually based on efficiency and being able to get more power from the same system, rather than having to install more panels. Cost is also considered, which is why there are many options available.