Table of Contents
Plan the Solar Panel Layout
Planning the layout and positioning of your solar panels is a critical first step in the installation process. You’ll need to take into account the total number of solar panels you’ll be installing, the dimensions of each panel, how they need to be oriented, and where you can physically place them. For residential systems, solar panels are typically installed on the roof, while larger utility-scale systems will use ground mounting structures.
When designing the solar array layout, panels should be arranged in long strings rather than short strings to minimize voltage drop losses. Analyze the paths where wiring runs will go and plan to minimize bends and long conduit runs. Consider how shading from nearby trees, chimneys, or other objects may impact certain locations. Optimize solar exposure by facing panels south if you’re in the northern hemisphere.
You’ll also need to determine the total power output of your planned array, taking into account the wattage of your selected solar panels and the number you plan to install. Reference the electrical code requirements for your system size and application. Any reputable solar installer can assist with designing an appropriate panel layout and wiring architecture.
Wire the Solar Panels
Once you’ve determined the solar panel layout, the next key step is wiring the panels together into strings. Use copper wiring that is properly sized based on amperage ratings and your system design. 12 AWG is commonly used for small to mid-size residential solar arrays. Copper wiring has less voltage drop compared to aluminum.
Solar panels are connected in series to increase voltage, while parallel connections are made to increase overall current or amperage. Series connections involve running a wire from the positive terminal of one panel to the negative terminal of the next panel. Parallel wiring connects all positive terminals together and all negative terminals together. Refer to your panel specifications for the maximum number of panels that can be wired in series safely.
Make sure all electrical connections are secure by using MC4 connectors to join solar panels together. MC4 connectors are weatherproof and designed specifically for solar applications. Use a crimping tool to attach the connectors to the copper wires. Follow all local codes and best practices for wiring, including proper wire sizing and circuit overcurrent protection.
Connect to Charge Controller
After the solar panels are fully wired in strings, the strings must be connected to a solar charge controller. The charge controller regulates the voltage and current coming from the solar panels going to the batteries. Without a charge controller, batteries could become overloaded. Choose a charge controller suitable for your system’s voltage and power output.
When connecting solar panels to the charge controller, the positive wire coming from the array connects to the solar positive input terminal on the controller. The negative wire connects to the solar negative input. Double check polarity. Maximum input voltage ratings vary based on charge controller specifications, so be sure not to exceed the input voltage, which could damage the controller.
Some charge controllers also have MPPT (maximum power point tracking) to maximize solar input. Consult the charge controller manual to ensure proper setup, connections, and configuration for your specific model.
Ground the System
Properly grounding a solar system is critical for safety and optimal performance. Solar mounts and components must be grounded in accordance with electrical code requirements. A ground rod is driven into the soil, providing a safe path to the earth for any stray electrical current in the system.
A ground wire is then attached to the ground rod, bonding all of the metallic components of the system together. This includes the solar panel frames, mounting equipment, conduits, and junction boxes. Ground wires are typically bare copper. Splices in ground wires should be avoided, but if necessary must include mechanical connectors like crimped sleeves.
The ground wire connects to the ground bus bar in the charge controller. Some systems may also utilize equipment grounding conductors as a redundant safety measure. Take care to properly size ground wires based on system amperage ratings. A licensed electrician can advise on proper grounding practices for your installation.
Test the System
After installing and grounding the solar array, test the system thoroughly to identify and correct any wiring issues. Check that all connections, including terminals at solar panels, charge controller, and in junction boxes, are tight and secure.
Use a digital multimeter to test voltages throughout the system. Start at the solar panels, verifying the open-circuit voltage. Then check voltages at the charge controller solar inputs under load. Make sure polarity is correct across all wiring runs and components.
Power the system on and connect loads like lights or motors to the output side of the charge controller. Monitor performance under load to identify any unexpected voltage drops. Consult technical specifications for expected voltage ranges. Finally, check ground connections with continuity tests or a clamp-on ground resistance tester.
Following solar best practices for wiring, grounding, and testing helps ensure a safe, long-lasting, and optimally performing PV system. Regular maintenance checks will also keep the system operating efficiently for years to come.