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Sizing Your Solar Controller: A Practical Guide

Sizing Your Solar Controller: A Practical Guide

Sizing Your Solar Controller: A Practical Guide

Hey mates! Greetings from Landon at Zero Grid. I've been immersed in the world of off-grid systems for a while now, and I want to shed some light on how we go about sizing your solar controller. It's not just about plugging in a solar panel and calling it a day; there's a bit more to it than that. So, let's dive in!

Choosing the Right Solar Panels

First things first, we need to select the right solar panels for your setup. The key here is to maximize solar capacity within the space available. Whether it's fitting smaller panels snugly next to each other or opting for longer, thinner panels, the goal is to utilize every inch of available roof space. Stick to reputable brands like Trina, Jinko, or Renogy to ensure quality and reliability.

Calculating Total Power Output

Once we've chosen our panels, we need to determine the combined wattage. This involves adding up the wattage of all panels in the array. It's crucial to keep panels of the same size together and avoid mixing different panels on the same solar charger.

For instance, if we have three 175W panels in one group, totaling 525W, we then divide this by the system battery voltage (e.g., 12V, 24V, or 48V) to calculate the potential amperage output.

For example 525(Watts) / 12(Volts) = 43.75(Amps). So then we would choose a solar charger around 40A

Selecting the Right Solar Controller

With our total power output in mind, it's time to choose a solar controller. Opt for one with a sufficient amperage rating to handle the combined output of your panels. Brands like Victron and Renogy offer reliable options with features like Bluetooth connectivity for easy monitoring.

Consider factors like solar input voltage and ensure it aligns with the specifications of your panels to prevent overloading or damaging the controller.

Understanding Panel Wiring Configurations

Now, let's talk about wiring configurations. Panels can be wired in series or parallel, each with its own benefits and considerations. Series wiring increases voltage, which can be advantageous for long cable runs but requires careful attention to voltage compatibility. Parallel wiring, on the other hand, maintains voltage while increasing amperage and offers flexibility for expansion and partial shading scenarios.

Finding the Right Balance

When designing your system, it's all about finding the right balance between voltage, amperage, and cable size. Sometimes a combination of series and parallel wiring is the best approach, especially for complex setups like bus conversions. This hybrid approach maximizes efficiency while keeping cable sizes manageable.


Designing an off-grid solar system involves numerous considerations, from panel selection to wiring configurations. By understanding these key factors and weighing the pros and cons of each approach, you can tailor your system to meet your specific needs while maximizing performance and reliability.

If you have any questions or need further assistance, don't hesitate to reach out. Thanks for tuning in, and happy off-grid living!

Cheers, Landon

P.S. Stay tuned for more tips and insights on off-grid living!

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