Can I Use Normal Cable Temporarily to Connect My Solar Panel to the Battery?

If you have a 100-watt 18-volt solar panel and a 40Ah battery, and you need to connect them temporarily without access to specialized cables, the answer is yes—and with some considerations to ensure safety and efficiency.

Understanding the Current Output

The current output of the 18-volt, 100-watt solar panel will be slightly less than 5 amps. This output can safely be passed through ordinary household extension cords designed for lighting and small electrical devices up to a few tens of feet. However, for longer distances, you should use more robust wires, such as heavy-duty power cords with wires larger than roughly 16 gauge. Specifically, 12 or 8 gauge wires would be sufficient for distances up to about 100 feet.

Ensuring Safety and Efficiency

Here are some guidelines to follow to ensure that your temporary connection is both safe and efficient:

For Short Distances (Up to a Few Tens of Feet)

If you only need to connect the solar panel to the battery for a short period—such as a day or two—the current output of your solar panel is manageable for household extension cords. These cords are generally safe for currents up to 15 amps, which is more than enough for your needs. Just ensure that the extension cord is rated for the appropriate voltage and current, and check for signs of wear or damage before use.

For Longer Distances (Up to About 100 Feet)

When you need to connect the solar panel to the battery over longer distances, you should use heavy-duty power cords. A 16-gauge wire can handle up to 15 amps, but more robust options are recommended. For distances up to 100 feet, 12-gauge or 8-gauge wires are sufficient. These wires are capable of handling the current and preventing any significant heat generation.

Double the Number of Wires or Get Thicker Wires

If you notice that the wires are getting warm during bright sunlight and while the battery is charging, it’s a sign that the wires may be too thin. In this case, consider doubling the number of wires or using thicker wires. Thicker wires reduce resistance and dissipate heat more effectively, ensuring a safer and more efficient connection.

Calculating the Required Wire Gauge

For a more detailed calculation, consider the following:

Based on these calculations, you can use any copper wire that is 14AWG or larger, such as 12 or 10 gauge wires. These wire gauges provide a margin of safety and ensure that the connection is reliable.

Conclusion

Using normal cable to connect your solar panel to the battery is safe and practical for short to medium distances—just ensure that you follow best practices for wire selection and installation. By adhering to the guidelines provided, you can maintain a safe and efficient electrical connection until you can obtain the necessary specialized cable.