How to connect Solar Panels(Part 2 Solar Controllers)

How to connect panels to a solar controller?

• Solar Energy is all about Control
• A Quick Recap with a New Twist
• How to connect solar panels to your controller
• What Should I Choose, 12 volt or 24, Parallel or Series?
• Conclusion

 

Solar Energy is all about Control

As we revisit our friend James’s journey, we find him and his supportive neighbor, Daniel, discussing the next crucial step in his solar panel setup: implementing a solar controller.

Under the tranquil shade of the garden table, James sat intently, captivated by Daniel’s illuminating discourse on the solar controller’s pivotal role. With each word, James began to comprehend the intricate dance of energy between the solar panels and the battery bank. The solar controller, he learned, acted as the conductor, orchestrating the symphony of power flow.

As Daniel spoke, James came to realize the vital significance of the battery voltage selection. It was the linchpin that held the entire system together. The battery choice is paramount in a solar system explained Daniel, shaping the selection of all other components. Its voltage determines the inverter voltage if wanted and controller type, setting the foundation for an efficient and harmonious solar setup.

Sitting at the garden table, James listened attentively as Daniel explained the significance of a solar controller in regulating the energy flow from the solar panels to the battery. Daniel highlighted that there are two types of solar controllers: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking).

 

“Okay, tell me more,” James replied, eager to learn.

“Well,” Daniel continued, “let’s start with PWM. It stands for Pulse Width Modulation. It’s a simpler type of solar controller that controls the charging by rapidly turning the solar panel’s current on and off. This maintains a fixed voltage level, suitable for charging the battery. PWM controllers are great for smaller solar systems where the solar panel’s voltage is almost the same as the battery voltage.”

 

Midnight Solar PWM Controller “Brat“

 

James nodded, “Got it. But what about MPPT?”

“MPPT stands for Maximum Power Point Tracking,” Daniel explained. “It’s a more advanced technology compared to PWM. MPPT controllers are like energy wizards. They can take a higher voltage output from the solar panel and then efficiently convert it to match the battery bank’s voltage. The magic lies in their ability to continuously track the maximum power point of the solar panel.”

 

Victron Energy 150 / 100 MPPT Solar Controller

 

 

“Maximum power point?” James questioned.

“Yes,” Daniel replied. “The maximum power point is the combination of voltage and current at which the solar panel produces the most power. MPPT controllers can dynamically adjust the load on the solar panel to keep it operating at that optimal point, extracting the maximum energy from the sun.”

James’s eyes sparkled with curiosity, “So, does that mean MPPT controllers are better?”

“In many cases, yes,” Daniel said. “MPPT controllers are more efficient and can harvest more energy, especially when the solar panel’s voltage is higher than the battery voltage. They work exceptionally well for larger solar systems or when multiple panels are connected in series.”

Daniel pointed out that PWM controllers are more budget-friendly but on the other hand, MPPT controllers are more versatile, as they can accept varying solar panel voltages and efficiently convert them to match the battery voltage. This flexibility comes at a slightly higher cost, but it can significantly increase the energy harvest from the solar panels.

James understood the importance of choosing the right controller type for his specific setup. Given that he had multiple solar panels, he realized that an MPPT controller would be a more suitable choice for maximizing energy efficiency.

With newfound insights, James felt more confident in his ability to finalize the connections in his solar energy system. He thanked Daniel for his unwavering support and guidance throughout the journey.

As the sun dipped below the horizon, painting the sky with hues of orange and pink, James and Daniel were filled with a sense of accomplishment. Together, they had navigated through the technicalities of solar controllers, understanding the importance of choosing the right type and voltage rating to optimize energy efficiency.

James’s cottage was now one step closer to being fully powered by sustainable energy. With a heart full of gratitude and a mind eager to learn more, he looked forward to each new day, knowing that his journey toward a greener and more environmentally conscious life was well underway.

At IOTG Solar, our core belief is in empowering everyone with knowledge about solar energy. Learning is the cornerstone to comprehend your system and unlocking the full potential of sustainable power solutions. Together, we can pave the way to a brighter and greener future.

 

A Quick Recap with a New Twist

Let’s recap how we connected solar panels in Part 1 of this series, but with a twist in the actual electrical values. Let’s make a note that solar panels labeled as 12 volts or 24 volts are not actually 12 or 24 volts.

The voltage of a solar panel can vary depending on factors such as temperature, sunlight intensity, and the type of solar panel.

Open Circuit Voltage (Voc): This is the voltage measured across the terminals of the solar panel when there is no load (no connection to a battery or load). The Voc of a solar panel can be higher than the labeled voltage, especially on sunny days and when the panel is cold.

For example, a 12-volt solar panel might have a Voc of around 18 to 22 volts, and a 24-volt panel might have a Voc of around 36 to 44 volts.

Maximum Power Point (Vmpp): This is the voltage at which the solar panel produces the maximum power output. The Vmpp of a solar panel is typically lower than the Voc and closer to the labeled voltage. For example, a 12-volt solar panel might have a Vmpp of around 14 to 18 volts, and a 24-volt panel might have a Vmpp of around 28 to 36 volts.

So lets connect some panels with real values to a PWM and MPPT

 

How to connect Solar Panels To Your Controller

Below is a setup with four 12 volt solar panels, each rated at 17 open circuit voltage (Voc) volts. When we connect these 17-volt panels in parallel, the actual combined voltage remains at 17 volts, and the total current increases to 22 amps (5.5 x 4).

Considering our PWM charge controller is designed for both 12 and 24-volt systems and can manage up to 30 amps of direct current (DC), this configuration falls well within its specifications, the voltage and current levels are comfortably within the controller’s limits, ensuring a suitable and effective arrangement.

Note: The parallel connection adds the amperage x 4 equalling 22 amps therefore a wire gauge size of #10 must be used as per electrical code and safety.

Below is a setup of 6-24 solar panels, each rated at an open circuit voltage (Voc) of 39 volts. We connect three of these 39-volt panels in series, resulting in an actual combined voltage of 117 volts and a constant current of 11 amps.

Now, we take another set of three panels, similar to the first, and connect them in series as well. This maintains the voltage at 117 volts but doubles the current to 22 amps due to the parallel connection.

Our charge controller is capable of handling up to 150 volts and 100 amps DC. In this setup, we stay well within these limits with a total voltage of 117 volts and 22 amps, ensuring a safe and optimal system configuration.

 

In this discussion, we won’t include a battery in the circuit, as we will delve into battery-related topics in the next article. For now, we’ll focus solely on the solar panel connection with controllers and other relevant aspects. Stay tuned for our next article where we’ll explore the importance of batteries in solar systems!

Note: In a series-parallel configuration with 22 amps flowing through our circuit, using #10 gauge wire is essential for safety and complying with electrical codes. Most solar panels come with 10 gauge wire and MC4 connectors, allowing you to maintain the same wire size all the way to the controller. This consistency simplifies installation and ensures efficient energy transfer.

The advantage of the MPPT controller becomes apparent as it allows higher solar panel voltages, resulting in lower current flowing through the wires. This enables the use of smaller gauge wires, saving costs on thicker copper wires. The MPPT controller efficiently handles energy conversion, making the entire system more cost-effective and efficient.

Once the charge controller receives the higher voltage and lower amperage from the solar panels, it manages this energy efficiently. It ensures your battery charges properly at the chosen storage voltage. In this way, the charge controller takes care of energy flow, optimizing battery charging and ensuring safety throughout the solar system.

 

What Should I Choose, 12 volt or 24, Parallel or Series?

12-volt solar panels in parallel are perfect for smaller systems like RVs, boats, vans, and other portable setups. They offer simplicity and flexibility, making them easy to install and expand. The electrical systems of most RVs and vehicles are already designed to accommodate 12-volt devices and appliances. Sticking with a 12-volt setup not only preserves the energy efficiency of your existing equipment but also eliminates the need for voltage conversion, which can consume additional energy. In essence, if your system is already operating at 12 volts, it’s advantageous to maintain this voltage to ensure seamless compatibility and optimal energy utilization.

 

However, when it comes to cabins, homes, or larger solar systems, a series-parallel 24-volt configuration proves to be highly advantageous.

In larger setups, series-parallel configurations allow for increased voltage and power output, optimizing energy efficiency and reducing voltage drop over long distances. By connecting multiple solar panels in series, the overall voltage rises, while connecting these series strings in parallel ensures the system can handle higher currents.

This combination results in several benefits for cabins and homes, such as:

1. Improved Performance: Series-parallel configurations yield higher voltages and currents, enabling the solar system to generate more power, especially during low-light conditions or partial shading situations.
2. Longer Cable Runs: In larger systems, cables need to cover more distance. With higher voltage in series connections, the current is lower, reducing power loss over extended cable runs.
3. System Scalability: Series-parallel configurations make it easier to expand the solar array by adding more panels. Simply connecting additional series strings or parallel branches allows for seamless capacity growth.
4. Lower System Costs: Higher voltage systems often require smaller gauge wiring, which can result in cost savings in the overall installation.
5. Charge Controllers Efficiency: Many charge controllers operate more efficiently at higher voltages, making the most of the solar energy collected.

While parallel configurations are user-friendly and work well for smaller setups, series-parallel configurations open up new possibilities for larger solar systems. They offer a more robust and efficient solution that can meet the demands of power-hungry cabins, homes, and other substantial off-grid applications.

 

Conclusion

In conclusion, understanding the complexities of solar panel connections and their interactions with controllers is essential for building an efficient and safe solar system. By using the right wire gauge, taking advantage of MPPT controllers for higher solar panel voltages, and optimizing battery charging with the charge controller, we can create a well-designed and cost-effective solar setup. In the next article, we will delve into the crucial role of batteries and their significance in completing a self-sustaining off-grid solar system. Stay tuned for more insights on building sustainable and eco-friendly power solutions!