Solar Fuse – IGOYE Solar Energy Equipment

Solar Fuse Vs. Breaker: Which One Should You Use?

HiManager1 — Mon, 10 Oct 2022 08:29:19 +0000

Solar fuse placement in a solar system
Resource: https://www.cruisersforum.com

Solar fuses and circuit breakers are both protective devices for electrical systems, but which one is better for your solar system? In this comparison of solar fuse vs. breaker, we’ll help you understand the major differences between the two devices. After that, we will give our verdict as to which one is better for solar systems.

To start us off, here is a quick definition of each device:

What is a Solar Fuse?

A solar fuse is a type of overcurrent protection device that is specifically designed for solar PV systems. It’s commonly used on the DC side of the system, but can also be used on the AC side and rated for AC currents.

Usually, fuses for solar system protection are sized in terms of their amperage and voltage. For example, a 10A, 600V solar fuse can safely interrupt a 10A current at up to 600V, while a 20A, 1200V solar fuse will interrupt a 20A current at up to 1200V.

It’s also common practice to size solar fuses at 1.25 times the rated current of the specific circuit. For example, if a circuit is rated for 15A, then a 20A solar fuse would be used.

What is a Circuit Breaker?

A circuit breaker is an electrical switch that automatically opens (and sometimes resets) a circuit in the event of an overload or short circuit.

Like fuses for solar, these circuit breakers are designed for use in photovoltaic (PV) systems. They are available in both DC and AC versions, but DC-rated solar circuit breakers are more common.

Solar circuit breakers are rated in terms of their amperage, voltage, and interrupting capacity. More importantly, the breakers will contain a means of handling the stubborn arcing of DC circuits.

Solar circuit breaker or resettable solar fuse
Resource: https://www.youtube.com/watch?v=z4ugx9WW-sI

Solar Fuse vs. Breaker

Now, on to the solar fuse vs. breaker dilemma and which one you should use in your PV system. First is a look at the main differences between the two devices. After that, we’ll see what is better for solar.

Solar Fuse vs. Breaker: Working

A PV solar fuse works by melting a conductor when the current flow through it exceeds the rated value. This interruption of current flow protects the circuit from further damage. In other words, it’s a sacrificial device – once the fuse melts, it needs to be replaced

On the other hand, circuit breakers generally use electromagnets, bi-metal strips (or both an electromagnet and bi-metal strip), or they can be electronic. This allows the circuit breaker to be reused after it has been triggered.

Solar Fuse vs. Breaker: Installation

Solar fuses are generally easier to install than circuit breakers, especially when it comes to retrofitting an existing system. This is because solar fuses don’t require any special wiring – they can simply be connected in line with the circuit or inserted into a solar fuse holder.

Circuit breakers, on the other hand, need to be mounted onto a panel or some other type of support, in addition to requiring some wiring. This can make installation more difficult, especially in systems where you need several installed.

Solar Fuse vs. Breaker: Response Time

The response time of a fuse, whether solar battery solar fuse, panel protection fuse or other type, is typically faster than that of a breaker (around 0.002 seconds).

This is because the fuse uses a simple melting mechanism to open the circuit, while most circuit breakers use a thermal mechanism, which can take slightly longer to respond.

In contrast, most breakers have a response time of around 0.02 – 0.05 seconds. In cases where fast response is critical, such as in short-circuit protection, fuses may come out as better protection devices. In some applications, though, the breaker delay also prevents unnecessary tripping and downtimes.

Solar Fuse vs. Breaker: Maintenance

Solar power fuses may appear to require more maintenance than breakers (they need to be replaced every time they “blow”). However, when rated correctly, a solar fuse in a PV system will rarely “blow.”

If they did, the solar fuse replacement cost would start to add up, and the inconvenience of having to replace them would be a hassle. In these cases, circuit breakers would be a better choice.

That said, it’s good to note that DC arcing can take a toll on breakers, causing them to wear sooner than expected and making properly sized fuses a better option for most solar installations.

Solar Fuse vs. Breaker: Cost

The solar fuse price is normally much lower than that of the circuit breaker price for the same amperage and voltage rating. This is because solar fuses are less complex than circuit breakers, and can be mass-produced more easily.

DC current circuit breakers, in particular, are usually more expensive than their AC counterparts. This is because they normally come with the ability to handle the arcing that is common in DC circuits or systems.

Solar fuse box with the fuses installed
Resource: https://youtu.be/vAGEeRt-L6E

Solar Fuse or Breaker?

Now onto the big question: Which one, between a solar fuse vs. breaker, is better for a PV system? The best answer, as with most things, is “it depends”, and one can use either. With that said, these points will help you make a decision:

If cost is your primary concern, then you may want to go with fuses. They cost less upfront.
If ease of installation is necessary (you are a DIY-re), then opt for fuses. They are easier to install and DIY-friendly.
If response time matters much, then go with fuses. They have a faster response time than circuit breakers.
If you want the convenience of being able to reset the device in the event of an overcurrent, then a breaker is the better choice. Breakers can also be used repeatedly, plus they can also act as isolation devices.

While both devices have their own advantages and disadvantages, the decision of whether to use a fuse or breaker in your solar system ultimately comes down to personal preference.

In general, though, fuses – whether PV string fuses or battery protection fuses- are better for small systems and circuit breakers are better for large systems. They’re also generally better for short-circuit protection, while breakers offer more flexibility and conveniences for larger installations

Besides, breakers can wear quickly when used in the DC circuits of a solar system. This usually happens because of the DC arcing that occurs when the breaker trips.

For that reason, many solar PV systems use a combination of solar system fuses and circuit breakers, with fuses being used mostly on the DC side and breakers on the AC side. This provides the best protection for the system while still keeping costs down

Conclusion

As a solar system owner, it’s upon you to make sure that your assets are protected against damage. That means using either solar PV fuses or breakers to protect your system against any potential electrical problems. Some people opt to use both, while others use just one or the other.

The bottom line is that it’s up to you to decide which device will work best for your system. Just make sure to do your research and choose the option that will provide the best protection for your solar PV system.

Related Resource

IGOYE Solar Fuse Catalog

The post Solar Fuse Vs. Breaker: Which One Should You Use? appeared first on IGOYE Solar Energy Equipment.

How to Determine Solar Panel Fuse Size

HiManager1 — Mon, 10 Oct 2022 08:29:13 +0000

Solar fuse installation points in a solar power system
Resource: https://www.youtube.com/watch?v=fZGj2cVnlHc

When it comes to fusing solar panels, the general rule of thumb is that the larger the wattage of the panel, the larger the fuse size should be. Use this guide to determine the right solar panel fuse size for your system, based on its specific wattage.

Solar Panel Fuse Size

Solar panel fuses are available in many different sizes. Solar panel fuse size refers to the amperage rating of the fuse or, in other words, the maximum amount of current that the fuse can safely carry.

The ampere rating is usually printed on the side of the fuse, and it will be represented by a number followed by the letter “A” (for example, “3A” or “15A”).

The letter represents the maximum current that the fuse can pass without blowing. So, a 30 Amp fuse for solar panel protection can safely carry up to 30 amps, and a 40 Amp fuse as much as 40 amps of current.

Why Fuse Solar Panels?

We fuse solar panel strings to protect the wiring (and the entire system) from the effects of fault currents such as those that result from short circuits.

A fault current or overcurrent would heat the wires and that heat could lead to a fire. The fuse “blows” or “opens” the circuit by melting and interrupting the flow of current before that happens.

Solar Panel Fuse Calculator

Solar panel fuse rating presents an important safety consideration. The wrong size can cause the fuse to either blow too easily or not blow at all in an overcurrent situation.

To calculate a solar panel fuse size, we need to obtain the maximum short circuit current (Isc) of the panels or panel strings. This will usually be on the sticker located on the back of the panel.

After we have the value, we can use the following formula to determine the minimum rating of the fuse needed for our application: Fuse size = 1.56 x Isc. Continue below for specific examples of these calculations.

Solar fuse box
Resource: https://www.youtube.com/watch?v=-64CyKEjwX0

What Solar Panel Fuse Size Do You Need?

Solar fuse installation can be a DIY project, or you could have a professional electrician do it for you. Either way, you’ll need to know the proper solar panel fuse size for your system. This sizing guide for solar panel fuses will help you choose the right size for the following panels arranged in both series and parallel.

90-watt solar panels
150-watt solar panels
200-watt solar panels
300-watt solar panels

Important! Note that these panels will usually require 30A fuses at the individual level. Our calculations are, therefore, aimed at finding the fuse to use between the array and the charge controller, at the combiner box or block.

What Fuse Size for 90W Solar Panel?

Suppose you have three of these 90-watt panels in series, each with an Isc of 4.6 amps. You’ll need a solar fuse size that can carry (4.6 x 1.56) = 7.1 amps, so an 8-amp fuse would be the smallest you could use in your system.

For 3 of these panels or 3 strings in parallel, you’ll need a fuse that can carry (7.1A x 3) = 21.3 amps, so a 25-amp fuse would be the type to look for. That’s because manufacturers only make these fuses in specific sizes.

What Fuse Size for 150W Solar Panel?

Let’s assume you have 150-watt panels arranged in series with each panel having Isc rating of 8.2 amps. In this case, you’ll need a fuse that can carry (8.2 x 1.56) = 12.8 amps. Rounding off the value, we find that your system would require a 15-amp fuse as the smallest size.

If you have the panels in parallel instead, you’ll need a fuse that can carry (12.8A x 3) = 38.4 amps. Again, rounding off the figure to the higher value, a 40-amp solar fuse would be the smallest you could use.

What Fuse Size for 200W Solar Panel?

What if you have three, 200-watt panels in series, and each has an Isc of 10 amps? Again, using our solar fuse calculator formula, we would need to multiply 10 x 1.5, which gives 15.6 amps. That means you would need to install a 20-amp fuse.

If the panels were in parallel, you’ll need your fuse rated (15.6A x 3) = 46.8 amps. In this case, we recommend using a 50-amp fuse as the smallest size. Remember, this fuse rating should match the size of the array wiring.

What Fuse Size for 300W Solar Panel?

For three 300-watt panels wired series, and assuming each panel comes rated of 11.7 amps for Isc, you’ll need a fuse that can protect against a minimum of (11.7 x 1.56) = 18.2 amps. Rounded off, the solar panel fuse rating for this system would be 20 amps.

And for the panels of this rating in parallel strings, you’ll need a fuse that’s rated (18.2A x 3) = 54.6 amps. Rounded off, the minimum size for this application would be 60 amps.

Note that these calculations to find the right solar panel fuse size are based on the most important parameters. Several other variables would need to be considered as well but these wouldn’t have as much impact. These include:

Wiring size and material
Array voltage
Operating temperature

We also advise that you follow the manufacturer’s recommendations for overcurrent protection devices. Many companies include guidelines to be used in determining the proper fuse size. Also, make sure you’re using the correct type of fuse.

Conclusion

Solar panel installations must be properly fused, or else serious damage to wiring equipment could result. In the worst of these fault current situations, the hot cables or equipment could cause a fire. If you are unsure about what solar panel fuse size to use, or have any other questions about installing solar fuses, our advice is to always consult with a qualified professional.

Related Resource

IGOYE Solar Fuse Catalog

The post How to Determine Solar Panel Fuse Size appeared first on IGOYE Solar Energy Equipment.

What is a Solar Fuse and Why or When Do You Need It?

HiManager1 — Mon, 10 Oct 2022 08:02:04 +0000

Solar fuse
Resource: https://www.rv.net/forum

A solar fuse is a type of fuse used in PV installations. It provides protection against overcurrent conditions, which helps prevent fires or damage to electrical components. Check out this post to learn more about the fuses for PV systems, how they protect solar systems, and more. The topics we will discuss include:

What is a solar fuse?
Why use a solar fuse?
Solar fuse location in a PV system
Types of fuses for PV systems
Solar fuse price

What is a Solar Fuse?

A solar fuse, or PV fuse, is a device that electricians use to protect solar circuits against excessive currents, also called overcurrents. An overcurrent refers to the abnormal flow of electricity that occurs due to a number of factors, such as:

Short circuits
Faulty equipment
Lightning strikes

The solar fuse, like most other fuses, uses a conductor that melts when exposed to too much current. This causes the circuit to break and interrupts the flow of electricity, thus preventing further damage or fire.

Solar fuses are specifically designed to protect solar circuits. That means they will adequately respond to fault currents that characterize PV systems. For that reason, solar power fuses must always be used in PV installations.

Why Use a Solar Fuse?

The primary reason for using photovoltaic fuses is to prevent the wiring from becoming too hot (due to fault currents) and causing a fire. In addition, fuses help protect solar equipment or devices from damage that can be caused by short circuits and other faults.

These solar components include panels, inverters, and solar batteries. In short, properly sized solar PV fuses ensure the longevity of your power investment. This makes it a critical safety device that should not be overlooked.

Types of Solar Fuses

Solar fuses can be different designs. They are also mostly classified based on their acting speed. In light of that, electricians usually have to choose between two main types of solar fuses – the fast-blow fuse and the slow-blow fuse.

The main difference between the two PV fuse types is in how they respond to an over-current. A fast-blow fuse will blow or melt almost immediately when exposed to an over-current, while a slow-blow fuse can handle small surges or inrush currents without blowing.

A fast-blow fuse is usually used to protect smaller circuits such as those found in electronic devices or circuits that will not experience any large inrush currents.

On the other hand, slow-blow PV fuses are best at protecting larger circuits such as those found in motors or power supplies, as they can handle the initial inrush current without blowing.

Solar fuse between the solar charge controller and battery
Resource: https://www.youtube.com/watch?v=Mes6ShwTqPw

Solar Fuse Location

Solar power fuses are typically installed at the point where they will protect a specific solar component, such as panels, cables, batteries, and so on. For that reason, it’s recommended to place them in these 4 places:

At the panel cables to protect parallel-wired modules or strings
Between the solar fuse block or combiner box and charge controller
Between the charge controller and battery or battery bank
Between the battery and inverter.

Solar Panel Fuses

Solar panel fuses are meant to protect individual panels and their cables. You install them on each cable of the panel, usually using a solar fuse block or in a combiner box. However, whether or not you need them will depend on the design of your system.

Solar panel fuses are necessary when you have three or more panels connected in parallel. That’s because, in this configuration, a single faulty panel could cause other panels to drive current through it.

Because the current in a parallel connection is additive, the fault current would be equivalent to a sum of the other panel currents. This would heat up the faulty panel cables to a point of even causing a fire.

If you have the panels in series, on the other hand, you will not need them fused. That’s because the current will not increase if one panel becomes faulty (panels in series only offer increased voltage and not current).

Solar Fuse Block Fuse

After the solar panel fuses in a parallel system (or outputs in a series wired system) are combined, a fuse must be installed. This type of solar DC fuse will provide protection to the wiring between the combined fuse block and the charge controller or if yours is a grid-tied system, the cables to the grid-tie inverter.

The manufacturer will most likely have stated this solar fuse size, or you can calculate it using the provided ratings in your solar system. The industry standard is to base your calculations on the short circuit current rating,(ISC), of the solar array or strings.

You can then calculate the required size using this formula: Fuse current rating = 1.56 x Isc

Solar Charge Controller Fuse

The role of the solar charger controller fuse is to protect the wiring from the solar charge controller to the battery bank. In its absence, the wire to the charge controller could become too hot during a fault current, and potentially catch fire.

In order to size the solar controller fuse, you would need to refer to the charge controller manual – if it comes fused, and whether it’s a PWN or MPPT controller.

That’s because whereas a PWN’s current is generally constant, an MPPT charge controller has its current fluctuating and the fuse sizing must accommodate for this.

Solar Battery Fuse

This is the last solar DC fuse. The solar battery fuse here is used to refer to the fuse that is located between the battery and the inverter.

The fuse protects both the wiring and the battery. Without it, a short circuit could cause a fire, as it would draw too much current from the battery.

The sizing of the solar inverter fuse is a bit more complicated, as you must factor in not only the inverter design but also the battery capacity.

Note that some inverters come already fused on either side (DC and AC) and you must consult its manual for the correct rating to use.

Solar Inverter Fuse

The other side of the inverter is the AC side. On this side, AC fuses or circuit breakers may be used. This is also the load side, and the fuses or breakers will protect the wiring from the overcurrents caused by faulty appliances.

A solar inverter fuse may be installed in the inverter or close to it. In the event of a fault such as a short circuit, the fuse will cut off power to prevent the wires from becoming too hot and causing a fire.

Types of solar fuses
Resource: https://www.youtube.com/watch?v=GyzrxAwxtgA

Solar Fuse Price

How much would solar PV fuses cost you to install? The price tag of a solar fuse will mainly be based on its size, type, and brand. However, you can expect to pay anywhere from $15 to $60 for most solar fuses.

Size is one of the main factors that affect the solar fuse price. The larger the fuse, the more expensive it will be. This is because larger fuses can handle more current and are therefore more expensive to manufacture.

As mentioned earlier, there are different types of these fuses. These will also have an impact on the price. Different fuse brands will also cost different amounts. To get the best deal, therefore, you may want to compare the prices of different companies.

Conclusion

A solar fuse ensures the cables in your solar system do not overheat and cause a fire when a fault current flows through them. PV fuses also help to protect the electrical components in your system from damage caused by over-currents from short circuits. Because of this, it is important to choose the right type and size of fuse for your application. Also, be sure to install the fuse in the correct location, as that will ensure proper protection.

Related Resource

IGOYE Solar Fuse Catalog

The post What is a Solar Fuse and Why or When Do You Need It? appeared first on IGOYE Solar Energy Equipment.

Fuses for Solar Panels: Do Solar Panels Need Fuses?

HiManager1 — Mon, 10 Oct 2022 07:57:52 +0000

Inline fuses for solar panels
Resource: https://forum.digikey.com

Fuses for solar panels are specifically meant to protect individual PV modules, but do you need them? Many people installing solar arrays do not know whether they need fuses or not. To answer the question, will explain the purpose of solar panel fuses, as well as when you need them. Keep reading!

Do You Need to Fuse Solar Panels?

It depends; if you have a single panel, the answer is usually no – your single panel will have the right wire size/gauge for its amperage or rated wattage, so there’s no need for fuses at the module level.

You also do not need a solar panel fuse if you have a two-panel system, whether wired in parallel or in series. In these configurations, a short in either panel will not cause an overcurrent in the other protected panel.

However, if you have more than two panels wired in parallel – that is, if your system consists of multiple panels connected together on one circuit but in parallel – then you will need a fuse for every panel.

Fuses for Solar Panels in Parallel

The current in a parallel wired system will be the sum of all the currents in the individual panels, so if one panel has a short circuit, the current that will flow through it can reach dangerously high levels.

For instance, suppose you have four solar panels wired in parallel, each with a maximum current of 4 amps. If one of those panels experiences a short circuit, the current flowing through it could be as high as 16 amps!

That would quickly lead to overheated cables – potentially causing a fire – which is why having fuses for solar setups of this kind is paramount. Fuses placed at the module level will protect each panel from such overcurrents, guaranteeing the safety of your system.

Fuses for Solar Panels in Series

Solar panels can also be wired in series, in which case the voltage of the system will be the sum of the voltages of the individual panels. The current, however, will remain the same, unlike when wired in parallel.

That means, if you have four solar panels wired in series, each with a maximum current rating of 4 amps, the total system current will be 4 amps. Even if one of the panels experienced a short circuit, the current flowing through the system would not exceed 4 amps, so fuses are not required in this type of system.

Solar panel fuse block
Resource: https://www.google.com/amp/s/www.sailmagazine.com

How to Fuse Solar Panels

Using fuses for solar panels is a pretty straightforward process. The protective device is usually an inline solar fuse which, in most cases, requires no installation skill. However, there are a few things to keep in mind when selecting the right fuse for your system.

First, you’ll need to determine the amp rating of your solar panel. This information can be found on the label of your panel or in the specs sheet. You’ll also need to know where to place the fuse. These two factors – solar panel fuse rating and location – are further explained below.

Solar Panel Fuse Rating

This is what to know when using fuses for solar panels wired in parallel: Unless your panels are rated below 50 watts each, the wire size installed by the manufacturer will usually be capable of carrying up to 30 amperes without overheating.

That means you will usually need to install a 30-amp fuse for each panel in a parallel system. This will protect each panel from a fault current of 30 amperes or less. At the combiner box, though, the entire system or individual strings must be protected by a fuse or fuse.

Solar Panel Fuse Location

Solar panel fuse location is another aspect of fusing solar systems that you need to be aware of. The National Electrical Code (NEC) and other industry standards require that overcurrent protection devices be installed as close to the source of power as possible.

In other words, if you’re using fuses for solar panels wired in parallel, each panel must have its own fuse, and those fuses must be installed at the module level – as close to the panel as possible.

Usually, you will need to house these fuses in a solar panel fuse box or combiner box. From there, you are required to add a common fuse for the circuit between the combiner box and solar charge controller (or inverter in a grid tie system).

Solar panel fuse diagram showing their locations
Resource: http://www.deepredmotorhome.com

Solar Panel Fuse or Breaker?

Solar panel fuses and breakers serve the same purpose – to protect your system from overcurrent – but they work in different ways.

A fuse “blows” or disconnects when too much current flows through it, effectively breaking the circuit. Once a fuse has blown, it must be replaced before the circuit can be re-connected.
A breaker, on the other hand, can be reset after it trips, or disconnects. This makes them more convenient than fuses. However, they are also often more expensive than fuses, except for some solar DC fuse types.

When it comes to PV module protection, fuses are often preferred, especially given that they are easy to use. They are also less mostly expensive and just as effective at protecting your array, making them a good choice for most situations.

Fuses for solar panels in an RV
Resource: https://www.youtube.com/watch?v=PU7oavdmbm4

Tips When Using Fuses for Solar Panels

Your solar panel system needs to be properly protected from overcurrents and fuses are one way to ensure this. They are both effective and affordable. If you’re a DIY, solar owner, you’ll also find them relatively easy to install. When hooking up fuses for solar panels, however, there are a few things to keep in mind:

1. Make sure you use the correct solar panel fuse size for your system. A too-large fuse won’t provide enough protection, while a too-small fuse can cause unnecessary downtime if it blows unnecessarily.

2. Use fuses in the right environment. High ambient temperatures can cause them not to work as intended.

3. Don’t use solar fuses as a substitute for other forms of protection, whether for the panels or other circuits in the system. They should be used in addition to things like circuit breakers and other protection devices.

4. Make sure fuses for solar panels are rated for DC current. Solar panels produce DC power, so AC-rated fuses are best used on the AC side, after the inverter.

5. Although your solar panel fuses will rarely blow, it’s still a good idea to keep spare fuses on hand. Having a few extras available will make it easy to replace a blown fuse and get your system back up and running quickly.

6. Keep an eye on your fuses. Check them periodically to make sure they’re still in working order.

Conclusion

To sum it up – if you have more than two panels in your system, and they are wired in parallel, then you will need fuses for each panel. Solar panel fuses will protect each panel by “blowing” or disconnecting when too much current flows through them, preventing damage to the rest of the system.

Just remember to use the correct size fuse for your system, and to keep a few extras on hand in case of a blown fuse. With proper protection in place, you can rest assured that your system will be safe from overcurrent damage.

Related Resource

IGOYE Solar Fuse Catalog

The post Fuses for Solar Panels: Do Solar Panels Need Fuses? appeared first on IGOYE Solar Energy Equipment.

Solar Fuse Sizing Guide for Solar Owners

HiManager1 — Mon, 10 Oct 2022 07:48:56 +0000

Solar DC fuses on a fuse block
Resource: https://forum.projectvanlife.com

When it comes to solar energy systems, one of the most important safety considerations is correctly sizing the fuses. This guide will help you understand why proper solar fuse sizing is so important for your PV system, and how to make sure you’re doing it correctly.

The Solar Fuse

A PV solar fuse is a critical component when it comes to protecting a solar system from electrical hazards. A properly sized fuse will help ensure that your system can safely handle any surges or spikes in electrical current, and prevent fires or damage to your equipment.

But while fuses for solar systems are important, they’re also one of the most misunderstood components. Many people do not know how to size them, which often results in electrical incidences such as wires that get too hot.

Why Solar Fuse Sizing Matters

To understand the need for proper solar fuse sizing, here’s how using the wrong size can lead to problems: Let’s say, for example, that you have a solar energy system with 5, 200-watt panels connected in parallel, and each panel produces a current of 4 amps.

Now, let’s assume that you choose a 10-amp fuse for each module in your system. This may seem to be fine since the maximum current output of your panels is only 4 amps. However, that wouldn’t be the correct way to size the fuses.

The reason has to do with the fact that your system can, without warning, experience surges that are much higher than the maximum output. For instance, a short circuit in one of the panels could cause the other panels to drive 16 amperes through the cables of the faulty panel and dangerously heat the circuit.

Solar Fuse Sizing Guide

So, how do you go about sizing solar fuse for your solar energy system? A lot depends on the specific solar fuse location. When fusing a solar system, there are generally 4 different locations where the fuses will be used:

In the solar panel circuits between one panel or string and another
In the DC combiner box for the cables leading to the charge controller or grid-tie inverter
Between the charge controller and battery
Between battery and inverter

Solar Panel Fuses

Manufacturers generally recommend a 30 Amp fuse for solar panel cable protection. That’s because most panels are installed with 10 gauge wires. These cables can safely carry 30A, which eliminates any possibility of fire due to overcurrents.

The fuses for solar panels are typically placed between each panel, or between strings of panels in a parallel configuration. This is to protect the panel cables from fault currents. The fuses are also normally installed at the combiner box.

Note that solar panel fusing does not apply to panels connected in series. In this configuration, the amperage does not exceed the ampacity of the wires. For that reason, fusing is not generally required.

Solar fuse combiner box/block
Resource: https://www.thevanimals.com

Fuse Between Solar Panel and Charge Controller

This DC solar fuse (or fuses) is typically located in the combiner box. Its purpose is to protect the cables leading from the box to the charge controller.

For a grid-tied system, this would be the circuit between the fuse box and the inverter. Here are the sizing guidelines for the fuse between the solar panel and MPPT or charge controller.

For this solar fuse, sizing is done using the array short circuit current rating (ISC). This value can be found in the manufacturer’s specifications sheet.
Therefore, for a 5-panel system with an Isc of 5 amps, you would use a 10-amp fuse (5 x 1.56 = 7.8). If you have multiple strings of panels, then you would need to use a fuse that is rated for the sum of all the strings’ short circuit currents.

A 30 Amp solar fuse and its holder
Resource: https://www.rv.net

Fuse Between Charge Controller and Battery

The next type of fuse is the fuse between the charge controller and battery cables. The size of this fuse will depend on the maximum current that can flow from the charge controller to the battery.

Here, you want to use a fuse that is rated 1.25 times the maximum current that can flow from the charge controller. Below is an example calculation when sizing a fuse between solar controller and battery:

If the charge controller is rated for a maximum current of 10 amps, then you would use a 12.5-amp fuse (10 x 1.25 = 12.5). It’s also important that you follow the recommended fusing as indicated in the solar charger manual.
That’s because solar charge controllers are different, and can be PWM or MPPT. They also sometimes may come equipped with overcurrent protection, and the fuse battery must be rated accordingly.

Solar fuse holder for battery fuse
Resource: https://youtu.be/GRKcZEIWihg

Fuse Between Batteries and Inverter

The last type of solar DC fuse use is used between the battery and inverter. This fuse is there to protect the battery-inverter circuit from overcurrent. We recommend using your inverter’s manual to determine the fuse size in this situation as some inverters contain fuses while others don’t.

Generally, when sizing the fuse between battery inverter cables, the standard method is to use the inverter’s maximum current output and multiply it by 1.25. Using the formula, let’s size a fuse when using a 1,000-watt, 12-volt inverter.

To get the maximum current output of the inverter, we need to divide the inverter’s wattage by its voltage. Therefore, for a 1,000-watt, 12-volt inverter, we have 1,000 watts / 12 volts = 83.3 amps.
Next, multiply the amp rating by 1.25 to get the fuse size, which comes to 104.1 amps (83.3 x 1.25 = 104.1). This rating will need to be rounded off to a fuse size that’s ready and available.

Conclusion

Proper solar fuse sizing is an important aspect of keeping your power system safe. As you can see, there are different types of solar fuses used in different parts of a solar energy system. These will usually be sized differently, depending on the location. Be sure to consider that when setting up your PV system. Also, always use the manufacturer’s instructions where and when provided.

Related Resource

IGOYE Solar Fuse Catalog

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