Do I Need A Fuse Between Battery And Inverter


Electrical appliances require a certain amount of current supply only and can be damaged by oversupply. Even electrical appliances need a guard and that is what a fuse does for them.

Basically, there are 3 types of fuses namely, One Time Only Fuse, Resettable Fuse, And Current Limiting & Noncurrent Limiting. Where they are used depends on different applications and appliances. There are 11 different types of fuses used in electrical systems divided into 2 main categories: AC (alternating current) and DC (direct current). While installing solar panel systems many people ask do I need a fuse between battery and inverter. And what type of fuse between battery and inverter? This blog will answer all these questions you are curious about.

Do I Need A Fuse Between Battery And Inverter?

JAN23do i need a fuse between battery and inverter
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Power inverters used for solar panels carry heavy wattage and thus they require accurate sizes of fuse to protect the device and wiring from fire, overload, and potential damage. You can place a fuse in other places like an MC4 fuse that goes between the solar panel and the charge controller. A fuse connecting the battery and inverter is the most important because this is the joint from where most current flows in the system.

1. Function of Fuse in a Circuit

There is a single purpose that circuit breakers and fuses serve, which is to prevent overheating and damage caused by current surges or short circuits to be connected to electrical equipment. Every electrical device has a fuse, even in-built fuses are used in electrical systems like solar power systems.

Fuses are an essential safety feature that acts as an amplifier when installed within the device. Or like a power inverter when used between electrical power sources and distribution devices.

2. Connection Load

A fuse has a current rating and works according to it and will blow off if the current exceeds the maximum limit of a fuse. This prevents excess current and high electrical energy from traveling through the wires to the connected electrical appliances.

When excessive current overheats the fuse element, the fuse blows off. As a result, the element melts and breaks the current flow between the battery and the inverter. Blowing off a fuse is a critical indicator of problems in a circuit.

3. Power Surge

To protect the devices and inverters from power surges you need a fuse. The power surge is a situation when loads connected draw more power than the rated power of the inverter and this results in a failed fuse. This inverter is protected against any excess or additional electric supply along with appliances from receiving too much current.

Another reason for the answer to do i need a fuse between battery and inverter is a power surge due to a fault in the inverter. Disconnect all the devices and troubleshoot the inverter but if the fuse still trips or blows off there is an issue in the inverter for sure. However, if troubleshooting the inverter solves the problem, check the batteries to see whether they are discharging the correct voltage and current.

Also Read: Can You Run Inverters in Parallel?

What if Fuse Blows Between the Battery and Inverter?

A blown fuse causes the electric supply to break, and the inverter will shut down. Due to this all-connected devices will stop working, which is why none of the appliances are at risk of overcurrent. However, the fuse needs to be replaced to restore the current flow. For this, turn off the inverter or disconnect the load to avoid any power surge.

Note: Appliances like refrigerators or air conditioners that need a start-up load need to be connected one at a time.

Also See: How to Check If Solar Panel is Charging Battery?

What Type of Fuse Between Battery and Inverter?

The type of fuse here refers to the size or power of fuse you need for the purpose. And for this, you need to use the general formula of (Continuous wattage (inverter wattage) / battery voltage * 1.25). If there is a 500-watt power inverter, you’ll need to use a 50-amp fuse between the battery and the inverter. There are 3 different locations where you need to place the fuse.

1. Between the charge controller and battery bank

2. Between the charge controller and solar panels

3. Between battery bank and inverter

What Size Fuse Between Charge Controller and Battery Bank?

The size of the fuse between charge controller and battery bank should have the same Amp rating as your charge controller’s output current rating. For example, if you are using a 40 A solar charge controller, the fuse should be at 40 Amps.

Also Read: What Size Fuse for 2000 Watt Inverter is Needed?

What Size Fuse Between Charge Controller and Solar Panels?

There are many sizes of fuses you can use between the charge controllers and solar panels. These sizes are: 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000 5000, and 6000 Amps.

You can determine the fuse size between your charge controller and solar panels by multiplying the total short-circuit current (in Amps) of your solar array by 1.56. After this, match the derived value to the equal, or next larger standard fuse amp rating.

Also See: Connecting Solar Panels in Series Vs Parallel

What Size Fuse Between Battery and Inverter?

JAN23do i need a fuse between battery and inverter

The size of fuse required depends on the size and voltage of inverter. There is a general rule or formula for this:

Continuous wattage/battery voltage * 1.25

Here, 1.25 is the safety factor so that fuse can handle slightly more power than its capacity but not too much as overcapacity may cause damage.

Let us take an example here for better understanding:

Inverter rating = 2000W

Battery bank = 12V

Formula= Continuous wattage/battery voltage * 1.25

= 2000W/12V*1.25

= 166.67, rounding it to 167A*1.25

= 208 Amps

Now, you need a fuse of slightly more capacity than the calculated amps. 220A or 250A fuse is recommended for the same.

Cable Thickness is Important

It is another factor while calculating the size of fuse for between inverter and battery. The thickness or gauge of a cable connecting battery and inverter depends on battery voltage and inverter wattage. Thin wires are recommended for small fuses, but thicker wires are required to handle the higher current running through it. After getting to know about all possible problems I guess your doubt do I need a fuse between battery and inverter is cleared.

Can an Inverter Work Without a Fuse?

In case your power inverter is working in inverter mode, it means the fuse has melted, or the input is not connected to the input. In case an inverter stops working, it is because the fuse blows off or is melted. This simply means to stabilize the current flow and prevent extra current from flowing through the circuit a fuse is required. A fuse is like a protective gate for your devices. So, its not ideal for a inveter to work without a fuse.

What Other Equipments are Required for Solar Power System?

The are some other equipment required for solar power systems-

1. Batteries: Power generated by solar panels is stored in batteries. It is wired between a power inverter and a charge controller. It is recommended not to connect the two devices without a battery connected within them.

2. Branch connectors: Multiple cables from solar panels need to be connected to the charge controller. The small device used to merge these cables is known as branch connector.

3. Cables: These are essentially required to connect various components together. The width and the material of cables must be according to the purpose they are used for. Also, for the same length, should also be as per requirement. Here is a list of cables required.

  • Cable for charging controller to battery
  • Cable lugs and crimping tools
  • Tray cable
  • Battery inverter cables
  • Solar extension cables

4. Charge controllers: There is a regulation called charge controllers, to prevent the overcharging of batteries in which the voltage and current are delivered from solar panels.

5. Power inverters: Solar panels produce direct current (DC) which is converted to alternating current (AC) by power inverters. Outlets of power inverters determine their efficiency. For example, 1000 watts, 1500 watts, and 2000 watts inverters can run different types of appliances.

So, the answer to do I need a fuse between battery and inverter is yes, you sure do. First of all, the inverter will work only in inverter mode without a fuse, and secondly, there will be the least protection for the inverter and connected loads. What type of fuse between battery and inverter? The answer to this depends on the wattage of the inverter and the voltage of the battery.

Recommended: What is Light Induced Degradation?

One response to “Do I Need A Fuse Between Battery And Inverter”
  1. Electrician electrician Avatar
    Electrician electrician

    Thanks for yur clear explanation it sounds great

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