Solar Power Technology – Why are Fuses Needed?

October 16, 2017

Complex solar power generation systems require the highest level of engineering and forethought so that the final solution is as reliable and efficient as possible. This includes anticipating the load being placed on the overall power system – something that requires safety precautions to reduce the risk of electrical shorts and system failure. Regarding the use of fuses, the most important thing to know is that they’re used to protect the entire electrical system wiring from conditions that might make components too hot and subject to catching fire. Secondly, fuses are also used to protect connected devices and components that might be subject to shorting in the event of system damage.

A good example of the use of fuses in an electrical system can be found in a basic 12-volt lead acid battery. If the battery is connected to a modern inverter (moving the power from DC to AC), there is almost always a fuse built into the inverter that will work to prevent a short before temperatures get too hot and cause a fire. In this example, the battery terminals, wiring, and AC/DC inverter will be wholly protected by the fuse hardware.
Solar Panel Fuses

Commercial-grade solar panels rated over 50 watts should have at least 10 gauge wires installed on them. These wires are capable of managing up to 30 amps of current flow, and if these panels are connected in series, there isn’t a need to increase current flow and a fuse isn’t required for the string. However, this is not the case with panels that are configured in a parallel installation.

Here’s an example: suppose there are four solar panels being installed, and each one is capable of handling up to 15 amps of current. If there is a short in one panel, this can draw all 60 amps towards that shorted panel. This can cause the wires terminating at that panel to well exceed 30 amps, resulting in a potential fire hazard. Any time solar panels are installed in parallel, an amp-specific fuse is required for each panel.

In the United States, The National Electrical Code (NEC) dictates that there be at least a 25% factor added if the power load is continuous, and that number grows again to 13.28 amps per panel. In a situation where there are four panels in a parallel configuration, then the combined current can theoretically be as high as 53 amps.

Regardless of the configuration of the solar panel array you are considering for your home or business, Urban Solar can work with you to ensure that your hardware is protected from shorts and fire hazards. This can be done through the use of strategically placed fuses and by selecting the most appropriate wiring and mounting hardware for your unique install. Contact us with your questions regarding solar power system installations, and be sure to ask about our complimentary energy assessment.