What is a PWM Charge Controller?

A PWM charge controller works by connecting the solar panels directly to the battery and regulating the voltage. It uses a rapid on-off switching technique to maintain the battery at its optimum charge level.

PWM controllers are simpler in design and generally more affordable than MPPT controllers. They are reliable and effective for solar system where the operating voltage (Vmp) of the solar array is close to the battery voltage.

What is an MPPT (Maximum Power Point Tracking) Charge Controller?

An MPPT controller optimises the power output from the solar panels by continuously adjusting the operating voltage of the solar array to ensure the maximum amount of power is generated from the panel for an operating condition, such as full sun, a cloudy day, or partial shading. It then converts the power generated from the panels to the correct voltage and current for charging the battery.

MPPT controllers are more complex and typically more expensive than PWM controllers. They are highly efficient, especially in varying sunlight conditions, and will help the panels to continue to generate power even when they’re partially shaded. They can increase the efficiency of a solar system by up to 30%.

Key Differences Between MPPT and PWM

1. Efficiency:

• PWM: Generally less efficient as it directly connects the solar panel to the battery, causing potential power loss when the panel voltage is higher than the battery voltage.
• MPPT: Highly efficient by converting the higher solar array voltage to current, ensuring maximum power extraction from the solar panels.

2. Performance in Varying Conditions:

• PWM: Performance drops significantly in cold, cloudy, or partially shaded conditions.
• MPPT: Remains highly efficiency in a wide range of conditions, adjusting to changes in sunlight to maximise power output. Will continue to generate power in cold, cloudy or partially shaded conditions.

3. System Compatibility:

• PWM: Best suited for systems where the Vmp of the solar panel is close to the voltage of the connected batteries. Can work well with 12V and 24V systems.
• MPPT: Ideal for larger systems and can handle higher voltage panels. Compatible with various battery types and voltages, including 12V, 24V, and 48V systems.

4. Cost:

• PWM: More affordable, making them a cost-effective choice for simpler or
  smaller solar setups.
• MPPT: More expensive but offers better long-term savings due to higher efficiency and better performance.

When to Choose a PWM Charge Controller

• Small Solar Systems: If you have a modest solar setup with closely matched panel and battery voltages.
• Budget Constraints: If initial cost is a significant factor, PWM controllers provide a reliable and affordable option.
• Stable Sunlight Conditions: If you are operating in an area with consistent weather and reliably sunny conditions, a PWM controller can be sufficient.

When to Choose an MPPT Charge Controller

• Higher Voltage Solar Systems: Ideal for systems where the solar array Vmp is greater than the battery voltage.
• Varying Sunlight Conditions: Perfect for areas with fluctuating sunlight, such as cloudy or shaded environments or inconsistent weather.
• Optimised Performance: If you seek maximum efficiency and long-term savings, an MPPT controller is the best choice.
• Higher Voltage Systems: Suitable for 24V, 48V, or higher voltage battery systems, making them versatile for diverse applications.

Conclusion

Choosing between an MPPT and PWM charge controller depends on your specific needs and the characteristics of your solar power system. While PWM controllers are a cost-effective choice for smaller systems with stable sunlight, MPPT controllers provide superior efficiency and performance, especially in larger systems and varying conditions. For the best results and to maximise your solar investment, explore our range of KickAss Solar Charge Controllers designed to enhance your off-grid adventures.