A solar battery charger is a device associated with a solar panel that can be used to regulate the battery charging process between the solar panel/grids and the battery charger.
The device is connected between a solar panel and battery, and this is important to ensure that the battery is charged correctly. Correct limits are put in the flow of energy between the solar panel and the battery so that both the devices do not experience any kinds of malfunctioning.
Initially, a DC-coupled solar charger controller was used, which basically served the needs of small-scale off-grid solar power systems.
The MPPT is a modern, advanced, and more efficient solar charger system that ensures better efficiency as well as precision while charging. It also has other extra features like DC load output which is used in lightning.
However, the DC load output technology is still used in small off-grid charge controllers, while the MPPT technology is used for heavier solar charge controllers. They are specially designed for large off-grid power systems with solar arrays.
MPPT Controller in Brief
The full form of MPPT is a Maximum Power Point Tracker. This is the latest technology related to solar power controllers, and it enables the solar panel to operate at its maximum potential with optimum voltage for maximum PowerPoint. The MPPT technology shows 30% more efficiency compared to contemporary PWM technology.
Solar panels produce variable outputs depending on the weather. MPPT charge control devices can match the solar panel voltage with the battery voltage to enhance charge efficiency.
The full power of solar panels may be employed in these systems by balancing voltage and current according to the P = V x I equation(where V stands for the voltage and I stands for the magnitude of current). When the weather is cloudy, the amount of electricity drawn from the panels is reduced to safeguard the voltage, and it is permitted to draw more current when the weather is sunny.
A maximum power point tracker is basically a very efficient technology to convert solar energy to a DC power converter to maximize the power output of the devices. The first MPPT was designed by AERL, an Australian-based company, back in 1985. Eventually, this technology became so popular that it has been used in all solar inverters nowadays.
The device matches the internal resistance of the battery charger with the solar panel characteristics resistance and hence draws the maximum amount of power output possible.
Usually, the thumb rule states that whenever the voltage level of the solar panel is more than 8V, the MPPT should be used for better efficiency.
MPPT Solar Charge Principle of Operation
Let us understand the mechanism of the working of the MPPT device.MPPT has two separate circuit systems.
Suppose you have a solar grid that is of the 100-watt panel. Assume that your battery needs only 8 V to charge; the MPPT, however, will extract the 100 watts divided by 8V output. As a result, the technology takes advantage of the whole amount of energy coming out of the solar panel.
It can efficiently manage the output regulation. Usually, the solar panel will deliver less output on cloudy days since direct sunlight will be absent. However, the MPPT can constantly track them and determine the maximum PowerPoint and output from the solar panel and regulate it accordingly. This technology is a passive system.
What are the advantages of MPPT?
There are tons of advantages of the MPPT technology, which makes it an ideal choice for many. They are as follows:
- They are much more efficient compared to the PWM regulators since they are more advanced technology.
- They can utilize the complete output from the solar panel. They are passive devices, and hence they drop the voltage to provide the maximum amount of current.
- Compared to other technologies, they are equally more efficient in low light conditions, cloudy days, etc.
- The device is specially designed for usage in large-scale solar voltage. So one can use a much higher voltage solar panel to get less magnitude of voltage drop.
Why are MPPT Better Than PWM and other contemporary technologies?
There are a lot of reasons why the MPPT is better than other similar devices (PWM, which stands for Pulse width modulation ).
The reasons are as follows
- Characteristics: The first significant difference between MPPT and PWM technology is charging capacity. While MPPT can be used for high capacity charging, the PWM is more classical and better for less charging capacity. However, the choice also depends upon several other factors like site conditions, system components size of Array load, and the users’ budget.
- Temperature as a factor: The MPPT technology is suitable for both sunny as well as cooler conditions. The Vmp1 grows when the working temperature of the solar module decreases. That’s because the solar panels’ peak power point voltage is around 17V at Standard Testing Conditions (STC = 25C°), while the battery voltage is at 13.5V. Excess module voltage can be captured by the MPPT controller and used to charge the batteries. As a result, an MPPT controller can deliver up to 25-30% more charge under chilly temperatures than a PWM controller. In contrast, because pulse width modulation technology charges at the same voltage as the battery, a PWM controller is unable to capture surplus voltage. However, when solar panels are used in warm or hot climates, their Vmp drops, and the peak power point works at a voltage closer to that of a 12V battery. Because there is no surplus voltage to send to the battery, the MPPT controller isn’t required, eliminating the MPPT’s advantage over a PWM.
- Size of the system: When selecting a charge control device, the size of the solar energy system is critical. For professional applications, MPPT charge control devices are the finest. PWM charge regulators can provide adequate performance in modest applications that do not require additional features. In modest projects, the efficiency difference between PWM and MPPT may not be sufficient to justify the price difference. However, it has a significant impact on the system’s performance in large projects.
HOWEVER, the MPW is not suited for the lower power system, and the PWM is much better suited for the same.
The reasons are as follows
- The PWM operates at constant efficiency for harvesting and hence it operates at the same rate regardless of the size of the array.
- The PWM is cheaper compared to the MPPT technology. So users having less budget can always look for this instead of the MPPT.
- The MPPT is much less efficient while working in low-power appliances. The recommended lower bound to use MPPT instead of the PWM is approximately 180 watts.
When do you need an MPPT solar charger?
The MPPT is not suited for low power appliances; however, it is best suited for high power appliances and is far more efficient.
As a general thumb rule, the MPPT charger controller should be used in all the higher power systems using multiple solar power grids instead of one. If the panel voltage is more than 8V, then the MPPT should be used instead of the PWM.
Additionally, they are 30% more efficient than the PWM when it comes to power output, hence giving more throughput than the PWM.
Increasing the panel voltage, the MPPT will give even more power output. For example, The 160W each panel, which uses 36 ordinary monocrystalline cells with a maximum power amp of 8.4A, will deliver roughly 8.6A at 12V. However, the 180W panel, which has four more cells, will provide the same amperage but with a 2V rise in panel voltage.
Is the MPPT controller worth it?
Yes, the MPPT is absolutely worth it when dealing with a high voltage solar panel grid. This is why they are used extensively in large firms over the PWM technology, and they are about 30% more efficient than PWM technology.
Along with it, they are much more convenient to be used during cloudy weather and dim light condition compared to PWM.So the throughput of the device is far more compared to other technologies.
The only few disadvantages are that they are costly, difficult to maintain, bulky, and relatively shorter lifespan compared to the PWM. However, the user experience will be much better with MPPT.
MPPT controllers are more expensive, but they provide more versatility in panel count. The PV module’s voltage will drop to match the battery bank, with a matching rise in current amperage.
A higher amperage will result in a faster recharge. The P = V x I equation will automatically adjust these solar charge controllers. As a result, unlike PWM, you will receive more power to charge the battery with no loss.
A panel array can have a higher voltage than the battery bank, thanks to the MPPT controller. This is important in locations with poor irradiance, especially during the winter when there are fewer daylight hours.
Compared to PWM, they deliver a 30% boost in charging efficiency. System expansion will be easier with more flexibility. This is important for business establishments. They usually have longer warranty durations than PWM types.
For high output battery devices, the MMPT should be used instead of the PWM technology. This is both helpful in terms of efficiency and throughput of the device and much more convenient to use. However, PWM should be given priority for devices with low power as they become inefficient for such chargers.