Fuse Your Solar Power System: How to Do It Right in 2022

fuse your solar power system

Power demand is forever increasing. Traditional energy generation has been supported, in the last decade, by the growth of renewable energy technology such as solar, wind and tidal. The need to store the energy generated, by both traditional and renewable methods, is becoming necessary to make sure power is continually provided where and when required. Fuse Your Solar Power System Properly is the vital to keep the solar pv system running well always.

Photovoltaic (PV) systems (or PV systems) convert sunlight into electricity using semiconductor materials. A photovoltaic system does not need bright sunlight in order to operate. It can also generate electricity on cloudy and rainy days from reflected sunlight.

You need to fuse solar panels or photovoltaic systems to prevent a surge of electricity. This can occur due to lightning, and you need to make sure that you use a fast-blow fuse on your system. However, if you’re unsure about how to fuse your solar system, we’ve compiled a list of tips to help you. Read on to learn how to fuse your solar panel system!

Do I need a fuse on my solar system?

If you’re installing a solar panel system on your home, you should add a fuse between the panels and the charge controller. This will protect against power surges and overcurrent, while also preventing the wires from becoming overheated. Some people opt not to install a fuse on their photovoltaic system, which is a good idea for small systems. However, for some household and RV solar systems, you should choose the right type of fuse for your system. Fast-blow fuses are the safest.

Fuses and Breakers are vary based on the size or your solar panels, typically, A solar panel that is over fifty watts should be fitted with a 30-amp fuse. If you’re using multiple panels in parallel, you can draw up to 40-60 amps from one panel. for instance, Short circuits could cause the wires to exceed 30 amps and catch fire, so you should use 30-amp fuses for your panels at least. When you’re using solar panels in parallel, you should also ensure that your system is full fused to prevent short circuits.

Types of PV Systems

With growing demand for PV systems, the utilities provided an option for the consumers to connect their systems to the grid. This step introduced a new term called “Net Metering.” Net metering allows the consumers to send back the electricity they generate from their PV systems to the grid. This is possible because of the grid-tied connection enabled by the utility. Similarly, we also have systems that are independent and do not require themselves to be connected to the grid such systems are called off-grid systems or standalone systems.

types of solar pv system

A “stand-alone or off-grid” system means they are the sole source of power to your home, or other applications such as remote cottages, telecom sites, water pumping, street lighting or emergency call box on highways. Stand-alone systems can be designed to run with or without battery backup. Battery backup systems store energy generated during the day in a battery bank for use at night.

solar pv system fuse
solar pv system fuse

Stand-alone systems are often cost-effective when compared to alternatives such as utility line extensions. Off grid systems are suitable for remote areas where there is good solar resource and utility power is not available or prohibitively expensive.

How do I fuse my solar Panels?

to Fuse your solar panels. When you connect your solar panels to your home, the fuse is the first line of defense. Depending on the number of panels and gauge wires, a panel’s fuse must be at least thirty amperes. A smaller fuse, or no fuse at all, might not be enough to protect your system from power surges or overcurrent. However, the larger your solar panel system is, the larger the fuse should be.

Install a junction box near your array. The junction box switches the different types of wires. The NEC requires that wire transitions occur inside an electrical enclosure. While electrical tape is often used, this is not considered a wire transition and should be done in a professional electrician’s shop. You should also avoid electrical tape and fuses made from plastic. This way, you won’t have to worry about a blown fuse.

Solar Batteries

Solar Battery stores electric power for operation during night time or during extended periods of cloudy or overcast weather when the PV array by itself cannot supply enough power. The number of days the battery storage capacity is available to operate the electrical loads directly from the battery, without any energy input from the PV array is called days of “autonomy” in a standalone PV system.

battery for solar pv system
battery for solar pv system

For common, less critical PV applications, autonomy periods are typically designed for between two and six days. For critical applications involving essential loads or public safety autonomy periods may be greater than ten days. Lead-acid or lithium-ion batteries are typically used.

Energy storage is a necessity as the world is becoming more electrified, leading to changes in system architectures and their overcurrent protection needs. In battery systems the protective devices are required to operate in DC systems which may have high faults currents and a number of lower over current situations.

Do I need a fuse between Charge Controller and battery?

There are two main types of charge controllers: Maximum Power Point Tracking (MPPT) Controller and PWM Controllers. In addition to the fuse size, you should make sure that your solar panel system’s fuse matches the fuse size of your charge controller. Each of these charge controllers draws a different amount of current. To determine which one you need, consult the manual that came with your charge controller.

Typically, for 30 Amp System, A 30 Amp fuse is recommended for parallel series connections. You can find it at any electrical hardware store. If you’re unsure of which type to buy, you can also check out Amazon’s selection of top-rated fuses. The 30-amp fuse is the safest choice for 30A solar power installations. However, if your solar panels aren’t very powerful, it’s a good idea to use a 20-amp fuse.

Fuses and circuit breakers

A fuse is an electrical safety device. It protects an electrical circuit against high currents. The fuse is placed in the supply cable to an electrical device. As soon as current flows through the fuse that is higher than its current rating, for a certain amount of time, the fuse will blow. Once the fuse has blown, no more current will flow into the circuit. Higher than expected current situations can occur when an electrical device develops a fault or when there is short-circuit in the electrical circuit.

you can use the fuse blocks to Manage all the fuse integrated.

The fuse protects against:

  • Severe overload – when more current runs in the system than it is rated for.
  • Short circuit – when one conductor accidentally comes in contact with another conductor.
fuse and breaker for solar power system
fuse and breaker for solar power system

Traditionally, a fuse contains a wire or a strip of metal that melts as soon as an unacceptable high current passes through the fuse. When the wire in the fuse has melted, the electrical circuit has been broken and no more current will flow in the circuit. Once the fuse has blown” it will need to be replaced by a new fuse to make the circuit operational again. These fuses are one-time use fuses. Once they have blown, they can’t be reset. They need to be replaced by a new one.

Another type of fuse is the automatic fuse, often called circuit breaker or miniature circuit breaker (CB or MCB). These devices interrupt the current flow when high current is detected. Sometimes they will reconnect after the high current event has passed, or they need to be manually reset. They do not need to be replaced like the traditional fuses.

There are 2 ways how these fuses operate, either thermal or magnetic or a combination of these. The thermal circuit breaker contains a bi-metal strip that heats up when over current flows. It bends when heated up and by doing so it will break the path of current. The magnetic breaker contains an electromagnet that is sensitive to a large current. When a large current flow the electromagnet creates a magnetic force that breaks the path of the current.

Location of the DC fuses :

Each consumer that connects to a battery needs to be fused. The fuse is placed in the positive cable. Each individual consumer needs to have an individual fuse. No matter how big or small the power rating of the equipment is. Batteries can potentially produce very high currents that can cause a fire. If the consumer develops a fault and internally short circuits, a very large current will flow, potentially causing a fire hazard. A DC circuit usually contains a main battery fuse, after which it branches of to the individual consumers. Each consumer has an individual fuse.

dc fuses for solar pv system
dc fuses for solar pv system

Location of the AC circuit breakers :

The circuit breakers are located near the entry point of the public grid and/or the generator into the switchboard. The AC breaker is placed in the live conductor or in both the live and the neutral conductor. Single or double pole circuit breakers are used. There usually is one main circuit breaker per AC supply, after which the supply branches off into a variety of groups. Each group contains a circuit breaker, protecting a group of AC consumers. Location of the PV array circuit breakers: A fuse needs to be located between a PV array and the solar charger.

AC fuses for solar pv system
AC fuses for solar pv system

Fuse ratings and how to select the correct fuse.

When selecting a fuse there are 4 selection criteria:

  • Current rating.
  • Voltage rating.
  • Speed.
  • Type.

It is important to choose the correct fuse that will match the circuit and match the power consumption of the equipment in that circuit. The rating of the fuse is displayed on the fuse or can be found in the fuse’s datasheet or its specifications.

Current rating If there is only one consumer in a circuit, the fuse will need to match the current rating of that consumer or the current rating of the cable, whichever is the lowest of the two. If there are multiple consumers in a circuit, then the fuse will need to match the current rating of the cabling in the circuit. Voltage rating The fuse voltage rating needs to be equal or bigger than the expected maximum voltage in the system.

The fuse needs to be specifically rated for the required type, DC and/or AC. Most DC fuses are suitable for 12V and 24V, but they are not necessarily suitable for 48 V and higher. Please note that not all fuses or circuit breakers can be used in both AC, and DC circuits.

If the fuse is able to be used for both AC and DC, the voltage for AC is often rated higher than the DC voltage rating. Also take care that circuit breakers might not be unidirectional, so for DC it matters which way they are wired into the circuit. Speed The speed of a fuse is the time it takes for the fuse to open when a fault current occurs. This is dictated by the fuse material, it’s mechanism, the current and the temperature.

There are slow and fast blow fuses:

  • Slow blow fuses are commonly used in DC applications that can be found in automotive and marine circuits. These circuits contain consumers with a high start-up current, like motors, or devices with capacitors, like an inverter. The slow blow fuse will withstand a high, short duration, initial current, enabling a motor to start.
  • Fast blow fuses are used in AC applications. AC consumers are often sensitive to changes in flow of electricity, so they need a fuse that can react fast, to protect the consumer. But in some cases, an AC consumer can have a high start-up current, this is equipment with electromotors, such as refrigerators, air-conditioners and compressors. In these scenarios a slower fuse will be needed

The selection of an appropriate fuse link should consider the circuit time constant and short-circuit current, as they will vary depending on the battery state of charge.

Voltage Dimensioning

The voltage rating of a battery fuse link indicates the maximum DC it has been designed to operate. In order to properly protect the battery system, the fuse link voltage rating must be at least equal to the maximum open circuit voltage of the battery.

One fuse link on its own should be able to operate at the maximum open circuit voltage of the battery, if two or more fuse links are in series in a short-circuit path, each fuse link should be rated above the maximum open circuit voltage of the battery.

The fuse links should be selected to ensure the circuit time constant is less than that the fuse links are tested to.

Current Dimensioning

The fuse link rated current is the RMS current that it can continuously carry without depradinp or exceeding the applicable temperature rise limits of the fuse-link under well-defined and steady-state conditions.

Useful Resources:

How to properly use a solar charge controller.

How to troubleshooting a solar charge controller.

Solar charge Controller Wiring Diagram

MPPT Solar Controller Controller Size Calculator

Solar Charge Controller Settings Instruction.

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