MARCH FAQ PART 1: WIRE SIZING 101 & FUSE SELECTION

How to Choose a Wire Size?

Choosing the right wire size for your solar panel system is important in ensuring that your system operates safely and efficiently. The wire size you need will depend on several factors, including:

-the distance between solar panels and your charge controller/inverter

-the maximum current of your system

-the type of wire insulation you choose

To determine the appropriate wire size for your system, calculate the maximum current that will flow through the wire. Do this by adding the max current of all the panels in your system and multiply that by a safety factor of 1.25. This will give you the current-carrying capacity of the wire you need.

Once you have the minimum ampacity, determine the appropriate wire gauge that you’ll need. Keep in mind that larger wire gauges have lower resistance but are able to carry more current over longer distances without losing voltage. Always side of caution and choose a slightly larger wire than you think you might need.

In general, a 10-12 AWG (American Wire Gauge) wire is sufficient for up to 50 feet, while an 8 AWG wire may be necessary for longer runs of up to 100 feet.

How to Install Solar Wires?

Here are the basic steps for installing solar wires:

First, determine the location of your solar panels, charge controller, and other equipment.

Secondly, select a wire that is rated for your solar application. The size of the wire will depend on the distance between the solar panels to the charge controller, as well as the maximum current capacity of the panels.

Thirdly, always connect your charge controller to your battery first, using the appropriate cables.

Next, connect you charge controller to your solar panel(s) with the panel’s positive (+) cable going to the controllers (+) terminal, and negative (-) panel cable to the controllers (-) terminal. Most controllers require bare wire ends for their terminals. You may need to strip the wires prior to connection. Once everything is connected, test the system to make sure it is functioning correctly, such as the voltage and current.

How to Size a Suitable Fuse for the Solar System?

Properly sizing fuses for your solar system is important to protect against overcurrent and potential fire hazards. The fuse size depends on the systems maximum current & the wire gauge you’re using. Determine your solar panels maximum current located on the back of the panel or on the spec sheet. For example, our 200W 12V solar panel (NPA200S-12I) short-circuit current (Isc) is 11.47A. Therefore, a suitable fuse rating would be slightly higher than 11.47A.

A common practice is to choose a fuse with a rating of 1.25 times the maximum current, which in this case would be 1.25 x 11.47A = 14.34A. Therefore, a suitable fuse rating for your 200W solar panel would be a 15A fuse.