Guide to Connecting Solar Panels in Series with Victron Charge Controllers
Guide to Connecting Solar Panels in Series with Victron Charge Controllers
Connecting solar panels in series with Victron MPPT (Maximum Power Point Tracking) charge controllers requires careful consideration of voltage limits and configuration. Here’s a step-by-step guide:
1. Understanding Series Connections
In a series connection, the positive terminal of one panel connects to the negative terminal of the next. This setup increases the total voltage while keeping the current constant. For instance, if each panel has a voltage of 40V and they are connected in series, the total voltage is the sum of each panel’s voltage.
2. Calculating System Voltage
To ensure compatibility with your Victron charge controller, calculate the total open circuit voltage (VOC) of your system:
[ Total VOC = VOC per panel x number of panels in series x times 1.1 ]
The factor of 1.1 accounts for temperature variations, which can increase the voltage. For example, three panels with a VOC of 40V each will have a total VOC of ( 40 x 3 x times 1.1 = 132V ).
3. Checking Controller Specifications
Ensure that the total VOC does not exceed the maximum input voltage of the Victron MPPT charge controller. Exceeding this limit can damage the controller. Victron MPPT controllers have different voltage ratings, so choose one that accommodates your array’s maximum VOC.
4. Choosing the Right Wire Gauge for Solar Installations
Selecting the appropriate wire gauge for a solar installation is crucial to ensure safety, efficiency, and minimal energy loss. The wire gauge determines the amount of current that can safely flow through the wire, which is critical in preventing overheating and voltage drop. Here’s a guide to choosing the right wire gauge based on common solar installation sizes:
Factors to Consider
- Current (Amperage): The amount of current the wire needs to carry.
- Distance: The length of the wire run between the solar panels and the charge controller or battery.
- Voltage Drop: The reduction in voltage that occurs as electric current moves through the wire. A lower gauge number means a thicker wire and less voltage drop.
Common Wire Gauges for Solar Installations
- 18 AWG (~0.82 mm²): 1 mm² cable, suitable for low current applications, up to 5A.
- 14 AWG (~2.08 mm²): 2.5 mm² cable, common for small systems, up to 15A.
- 12 AWG (~3.31 mm²): 4 mm² cable, used in medium-sized installations, up to 20A.
- 10 AWG (~5.26 mm²): 6 mm² cable, for larger systems, up to 30A.
- 8 AWG (~8.37 mm²): 10 mm² cable, for high current requirements, up to 50A.
- 6 AWG (~13.3 mm²): 16 mm² cable, used in high-current or long-distance setups, up to 65A.
6 mm² cable, for larger systems, up to 30A, this is going to be most common wire size used in PV in Australia, as the MC4 Connectors are normally limited to 30A. This cable size is standard for medium to large residential and small commercial solar systems, ensuring safe and efficient energy transfer. It’s readily available from most electrical and solar supply stores in Australia.
Voltage Drop Consideration
For optimal performance, aim for a voltage drop of less than 3%. You can calculate the required wire gauge using the formula:
Voltage Drop = 1000 (2×Length×Current×Resistance per unit length)
Where:
Resistance per unit length is the resistance of the wire (in ohms per meter)
Length is the one-way distance of the wire run (in meters).
Current is the amount of electrical current flowing through the wire (in amperes).
Where length is the one-way distance in feet, current is in amperes, and resistance is the wire’s resistance per unit length (in ohms per 1000 feet). This formula helps ensure that the wire gauge chosen minimizes energy loss and maintains system efficiency.
Conclusion
Choosing the right wire gauge is a balance between current carrying capacity, voltage drop, and cost. Overestimating the required gauge can lead to unnecessary expenses, while underestimating can cause safety hazards and inefficiencies. Always consult with a qualified electrician or solar installer to ensure that your wire sizing meets local electrical codes and safety standards.
5. Grounding and Safety
Proper grounding of the solar panel array is crucial for safety and system longevity. Follow local regulations and manufacturer guidelines for grounding methods. Additionally, use overcurrent protection devices like fuses or breakers to protect your system components.
6. Monitoring and Maintenance
Regularly check connections and the performance of the system. Victron controllers often come with monitoring capabilities, allowing you to track system performance and make adjustments as needed.
For detailed specifications and guidance, always refer to the Victron MPPT charge controller manual and consult with a professional installer.
Victron MPPT Installation Guide
SmartSolar MPPT 150/70 up to 250/100 VE.Can here
Be sure to follow Australian Standard AS/NZS 5033 , AS/NZS 3000, PV cables can be certified to the IEC 62930 standard.
