Solar street lights have become increasingly popular due to their energy efficiency and environmentally friendly nature. However, in order to ensure the proper functioning of these lights, it is important to have the right solar charge controller.
There are two main types of solar charge controllers – PWM and MPPT – that are commonly used for solar street lights. This blog will provide an overview of these technologies and explore which one is better suited for solar street lights.
First let’s see What are PWM controllers?
PWM (Pulse Width Modulation) controllers are the most basic type of solar charge controller. They regulate the voltage output of the solar panels to prevent overcharging the batteries.
PWM controllers work by rapidly turning the charging circuit on and off, which essentially controls the amount of voltage that is being applied to the battery. As the battery reaches its full capacity, the PWM controller will reduce the amount of power being supplied to prevent overcharging.
PWM controllers can be relatively inexpensive, making them a popular choice for small-scale solar systems. However, they are not as efficient as MPPT controllers and may not perform as well in low-light conditions.
A typical PWM solar charge controller might have a voltage range of 12-24V DC, a maximum solar panel input voltage of 55V DC, and a charging current of up to 20A.
Then What are MPPT controllers?
MPPT (Maximum Power Point Tracking) controllers are a more advanced type of solar charge controller. They are designed to maximize the amount of power that can be harvested from solar panels by dynamically adjusting the voltage and current to find the optimal operating point. This means that MPPT controllers can operate at a higher efficiency than PWM controllers, especially in low-light conditions.
MPPT controllers can also protect the batteries from overcharging, just like PWM controllers. However, they can also protect the batteries from over-discharging by monitoring the battery voltage and disconnecting the load if necessary.
A typical MPPT solar charge controller might have a voltage range of 12-48V DC, a maximum solar panel input voltage of 150V DC, and a charging current of up to 60A.
After knowing the basic technologies of MPPT&PWM controller, you may want to know which one is better for solar street lights?
When it comes to solar street lights, the choice between PWM and MPPT controllers will depend on several factors, including efficiency, cost, and performance in different conditions.
Efficiency: MPPT controllers are generally more efficient than PWM controllers, especially in low-light conditions. In fact, MPPT controllers can increase the amount of power harvested from solar panels by up to 30% compared to PWM controllers.
Cost: MPPT controllers are typically more expensive than PWM controllers, but they can be more cost-effective in the long run due to their increased efficiency and ability to maximize power output.
Performance in different conditions: PWM controllers may not perform as well in low-light conditions as MPPT controllers. However, PWM controllers may be more suitable for small-scale solar systems or in situations where cost is a primary concern.
A study conducted in Australia found that an MPPT controller was able to increase the energy output of a 190W solar panel by up to 22.5% compared to a PWM controller in low-light conditions. This translates to an additional 136Wh of energy per day, which can make a significant difference in areas with limited sunlight.
Here are some recommendations based on specific scenarios and needs:
If efficiency is a top priority and cost is not a concern, an MPPT controller may be the best choice for solar street lights.
If cost is a primary concern or the solar system is relatively small, a PWM controller may be a more cost-effective option.
If the solar system is located in an area with limited sunlight, an MPPT controller may be a better choice as it can maximize the power output from the solar panels. On the other hand, if the solar system is located in an area with abundant sunlight and the cost is a major concern, a PWM controller may be a suitable option.
When choosing a solar charge controller, there are several factors to consider. One of the most important factors is the number of solar panels needed for the system. The controller is determined by the number of solar panels because it needs to be able to handle the maximum current that the panels can generate. If the controller is undersized, it may not be able to handle the current, which could lead to damage or malfunction.
For example, if you have one 150W MONO solar panel with a maximum output current of 8.33A and a voltage of 18V, you would need a controller that can handle at least 8.33A. A 10A controller would be sufficient for this panel, but if you were to add more panels in the future, you would need to reevaluate the controller size to ensure it can handle the additional current.
Another important factor to consider is the compatibility of the controller with the type and size of the battery used in the system. Different batteries have different charging requirements, and it’s essential to choose a controller that is designed to work with the specific type and size of battery used in the system.
Let’s say you have a solar street light system that uses a 12V 100Ah lead-acid battery. This type of battery requires a specific charging profile, which is different from other types of batteries such as lithium-ion or nickel-cadmium batteries.
If you choose a controller that is not compatible with a lead-acid battery or is not designed to work with a 12V 100Ah battery, it may not provide the proper charging profile, which can lead to poor performance, reduced lifespan, and even damage to the battery.
For example, the Renogy Wanderer 10A PWM Solar Charge Controller is designed for lead-acid batteries and can support a maximum battery capacity of 120Ah. If you were to use this controller with a larger battery, such as a 12V 200Ah lead-acid battery, it may not be able to provide the necessary charging profile, which can lead to a reduced lifespan of the battery.
Finally, some solar charge controllers come with additional features such as remote control and monitoring capabilities. These features can provide greater convenience and allow for better monitoring and control of the solar system.
MPPT controllers typically have a longer lifespan compared to PWM controllers. However, the lifespan of an MPPT controller can be affected by various factors such as the quality of the components, operating temperature, and environmental conditions. For example, a high-quality MPPT controller may last up to 10-15 years or more, while a lower quality controller may fail within a few years.
To maximize the lifespan of an MPPT controller, regular maintenance is important. This can include cleaning the controller and solar panels, checking and tightening connections, and ensuring proper ventilation for heat dissipation.
How do you know if this size MPPT controllers will suitable for your solar lighting system?
When choosing an MPPT controller for a solar street light system, it’s important to select one that is appropriately sized for the solar panel and battery capacity. A general rule of thumb is to select an MPPT controller with a rated capacity that is at least equal to the total power of the solar panel system.
For example, if a solar street light system has a total solar panel power of 300W and a battery capacity of 100Ah, an MPPT controller with a rated capacity of at least 30A would be appropriate.
Conclusion
In conclusion, both PWM and MPPT controllers are important components in solar street light systems. PWM controllers are more cost-effective and simpler to use, while MPPT controllers offer higher efficiency and better performance in low sunlight conditions. When choosing a solar charge controller, it’s important to consider factors such as the number of solar panels needed, compatibility with the battery type and size, and any additional features like remote control and monitoring. With proper maintenance and sizing, an MPPT controller can provide reliable and efficient performance for many years.