What is Maximum Power Point Tracking (MPPT) in a Solar System?
The full form of MPPT is Maximum Power Point Tracking. It is an algorithm which maximises the power output of a solar system when it is stored in a battery or sent to the grid via an inverter. As the electricity output of a solar system can vary according to conditions, it is important to ensure maximum efficiency even as the power output fluctuates.
The full form of MPPT is Maximum Power Point Tracking. It maximises the power output of a solar system when it is stored in a battery or sent to the grid via an inverter. As the electricity output of a solar system can vary according to conditions, it is important to ensure maximum efficiency even as the power output fluctuates.
How Does MPPT Work?
An MPPT converts one form of Direct Current (DC) into another. It is a DC-to-DC converter with high high-frequency.
To understand how an MPPT in solar PV systems works, you need to understand the concept of maximum power point. But before you know what maximum power point means, you must understand the following physics formula:
Power (Watts) = Current (Ampere) x Voltage (Volt)
As per this formula, current and voltage are inversely proportional if the power stays constant. More than the optimum voltage can lead to a drop in current. You can understand this from the following graph:
Source: Pouyan Pourbeik/ResearchGate
MPPT maintains the ideal combination of current and voltage to ensure maximum power output. The required current and voltage is found at the maximum power point.
The voltage and current output of a solar system varies throughout the day. At certain times the voltage may be high and the current may be low in the solar system due to factors like the effects of temperature, resistance and recombination losses. Here’s an example:
In the above example, the power output at both points a and c is lower than at b. An MPPT always tries to maintain the power output at this level.
What is an MPPT Solar Charge Controller?
You need an MPPT solar charge controller when you are charging a battery.
The voltage of a battery is lower than the output voltage of solar panels. It leads to a significant loss of solar electricity. An MPPT in solar charge controller can help you by increasing the output current of the solar system while maintaining the voltage at the level of the battery. This ensures full utilisation of the electricity generated by the solar panel.
We will illustrate its benefit in the next section with an example.
PWM vs MPPT: Difference Between These Charge Controllers
PWM stands for Pulse Width Modulation. It is a less efficient type of charge-controlling technology.
A PWM charge controller reduces the output voltage of a solar panel to the level of the battery’s voltage. This significantly reduces the power stored in the battery.
For example, if a solar panel has a maximum voltage output of 30 V and a maximum current output of 10 A, then its maximum power output is 30 V x 10 A = 300 W. But if the voltage of the battery is 12 V, then the power it can store is 12 V x 10 A = 120 W. Thus, 300 W – 120 W = 180 W is being wasted.
If the voltage remains at 12 V, then the power output would need to be 300/12 A = 25 A. The MPPT will send a power output of 12 V and 25 A to the battery, thus ensuring an output of 12 V x 30 A = 300 W. Thus, no electricity will be lost.
Assuming that the battery can absorb this much current, it will ensure that the full power generated by the panel is stored in the battery.
Please note that in practical terms, some electricity will be lost as heat.
PWM charge controllers can be used for small solar systems with a low power output. If more than 1 solar panel is installed, they must be connected in parallel, unless they have a very low voltage.
PWM charge controllers are not worthy of a large solar system. Instead, you should use an MPPT charge controller in such a scenario.
Types of Maximum Power Point Trackers in Solar Inverters
There are 2 types of MPPT solar inverters which are available:
Single MPPT: In these inverters, an entire array of solar panels is connected to an MPPT. Any fluctuation in the output of any panel will affect the entire array.
Multi MPPT: When an inverter has more than 1 MPPT, multiple arrays can be connected with multiple MPPTs. It is especially useful if the efficiency of one of the arrays varies due to factors such as shadow.
Till now we have discussed the role of MPPTs in solar inverters. Now, you can read our blog if you are interested in the best solar inverters in India.
Panel Tracking Vs MPPT Solar Inverters
It is important to not confuse solar panel trackers and MPPT inverter solar.
A solar panel tracker is installed in a mounting structure to maximise the electricity generated by the solar system. It does so by following the movement of the sun, thus ensuring that the sunlight falls perpendicularly on the solar panels. The efficiency of a solar panel is maximum when electricity falls perpendicularly on the solar panels.
This is different from the functioning of an MPPT, which optimises solar electricity as per the maximum power point. We have already explained the functioning of an MPPT in the section “How MPPT Works?”
Want to know more about solar panel trackers? Read our blog on solar tracking systems.
Advantages of MPPT
The following are some of the advantages of MPPT in a solar system:
1. Increased Efficiency
The energy output of a solar system is significantly optimised by an MPPT. Maintaining the ideal voltage and current output ensures that very little solar electricity is lost during the transmission.
2. Adaptability to Varying Conditions
The generation of solar electricity varies due to factors such as weather, intensity of solar radiation, and shadow falling on the solar panels. An MPPT ensures optimum power production irrespective of the conditions in which the solar system is working.
3. Return on Investment
By maximising energy generation, an MPPT ensures that you get the maximum return on your investment in a solar system.
An MPPT is a vital component of a solar system charging system. It boosts the electricity produced by the solar system and ensures minimal electricity loss. By maintaining the ideal combination of voltage and current, it keeps the power at maximum power point. Understanding what is MPPT is important for selecting the right MPPT for your solar system.
Frequently Asked Questions
MPPT stands for maximum power point tracker. It is used to maximise the output of a solar system so that loss of electricity is minimised during transmission.
Yes, an MPPT will work in cloudy weather and generate a power output as per the prevailing weather.
Yes, an inverter can have more than 1 MPPT.
2 Comments
Anatoly Kozlov
I have completely understood MPPTs from this blog. Look forward to reading more blogs from you.
Prakash Kumar
Excellent blog