31/10/2024

Optimising charge controllers can enhance energy yield, reduce operational costs and improve overall system reliability. Regular monitoring and maintenance are crucial to ensuring optimal performance in any setting. In addition, understanding the application’s specific needs will help users optimize each system’s charge controller.

Charge controllers are voltage and current regulators that prevent batteries from overcharging. They are crucial elements of solar power, maintaining the system’s safety, efficiency and longevity. Without correct solar regulation batteries will exceed their safe charge limits and will cause damage to the wider electrical system.

Two principal types of charge controllers exist:

• Pulse Width Modulation (PWM) charge controllers: Compact and efficient, PWM controllers operate at battery voltage, making them ideal for smaller setups commonly used in caravans and 4x4s. Their design maximizes energy production, particularly in cooler climates when the solar panel voltage exceeds battery voltage, while also a good choice for hot environments and are well-suited for solar module configurations when the array voltage is matched to the battery bank voltage, offering a practical and affordable solution for mobile power needs.
• Maximum power point tracking (MPPT) charge controllers: MPPT charge controllers use innovative technology to allow the array to operate at its maximum power voltage. They allow solar arrays to be installed and operate at much higher voltages which can lower the array currents, this can mean less voltage drop. They operate by converting excess input voltage into output amperage, making them suitable for large configurations with lower per-watt costs.

One of the most essential elements in charge controller optimisation is size. Solar charge controllers are rated and sized by the solar module’s current and system voltage. The most common controllers for Caravan and 4×4’s are 12-volt and 24-volt controllers.

Some tips and tricks for choosing the ideal size charge controller include:

• Determine the system voltage: Each charge controller should match the battery bank’s voltage to ensure efficient charging.
• Calculate the maximum current: This calculation provides the base current the charge controller must handle under normal conditions.

PWM controllers: Locate the Short Circuit Current Isc(A) on the back of the panel. I.e. our 190W has a Im(A) of 9.5A. so if you are using 3 panels you need a controller over 28.5A. So a 30A controller would be perfect.

MPPT controllers: MPPT controllers will normally state what the maximum Wattage they can harvest for each battery Voltage i.e. 12v or 24v use this number to determine the amount of solar that will work for this controller. It is common practice to over spec the MPPT controller up to 20% i.e. if the controller is rated at 600w then a Solar array up to 720w in acceptable.

The ideal charge controller should have a current rating equal to or greater than the maximum current and 25% buffer.

Aside from size, several other considerations have a bearing on the choice of charge controller, including:

• Load control: Some charge controllers have a function that allows users to utilise DC loads directly from the battery bank. Load control also helps manage power distribution and prevents the battery from deep discharge. It disconnects loads when the battery drops below a certain threshold, maintaining optimum efficiency and preventing damage.
• Solar efficiency: MPPT controllers can improve the energy harvest from solar panels, especially for large or high-performance systems.

Charge controller optimisation may differ depending on the application. Some industry-specific optimisation strategies include:

• Caravan, recreational vehicle (RV) and marine applications: Space is always a challenge in caravans, RVs and marine settings. Use compact, high-efficiency MPPT controllers to maximise limited space and implement smart controllers with programmable features (PWM controllers have this function as well) to manage electricity consumption during travel.
• Telecommunications power systems: Integrate redundant charge controller systems to ensure no single point of failure, which ensures uptime and reliability for telecommunications infrastructure.

Charge controllers play a pivotal role in harnessing solar energy — an unlimited resource that can power the world many times over. Optimizing these devices allows humans to tap into this potential more precisely and efficiently.

Technological advancements in charge controllers — such as adaptive tracking and real-time analytics — are steering the industry toward smarter, more responsive systems. These innovations will continue to shape the future of solar technology, allowing users to maintain efficiency and longevity in diverse operational environments.

Sources:

• https://www.sciencedirect.com/topics/engineering/charge-controller
• https://www.vpslp.com/blog/how-to-solar-power-a-business/
• https://www.electricaltechnology.org/2021/02/solar-charge-controller-sizing-mppt-pwm.html
• https://www.researchgate.net/publication/277639636_Adaptive_control_of_solar_tracking_system

Written by Jack Shaw