Solar panel fuse or breaker?

Are you wondering if you need a fuse or breaker for your solar panel? If you are, you may also be wondering which is the best option? How we answer these questions depends on the circumstance of the solar panel or array. 

Generally, a solar controller would be enough to handle the excess flow from a solar panel. However, there are circumstances where the voltage from the solar panel or array may become more than a solar controller can handle.

In those situations, you would want a safety link between the solar panel and the controller. A safety link, in this case, would be either an inline fuse or a breaker. 

In this blog, we discuss:

  • How to determine if you need to add a fuse or circuit breaker to a solar panel.
  • Which is better a fuse or a circuit breaker for solar panels.
  • Why Adding a fuse or circuit breaker is a good move.

Keep reading as we go over why you need a fuse or when you need a breaker for your solar energy system.

Along the way, we also give a few additional and essential pieces of information that can help you make a more informed decision about how you handle excess energy flow from your solar panel. 

Circuit brekaer on a wall

Do you need a fuse or breaker for your solar panel? 

The short answer is that you do not need a fuse or a breaker if your solar panel or a solar array is installed correctly.

A fuse or breaker is an accessory that provides an additional layer of safety for your solar components, and many solar contractors recommend that you use them.

However, there is no harm in adding a fuse or circuit breaker, and doing so can save you some serious dollars. 

Reasons why installing a fuse or breaker is a good idea?

  1. The Solar Controller is Too Small – The primary reason to install a fuse or breaker is when the voltage from the solar panels is too much for the solar controller to handle.
  2. Lightening is a Possibility – Even though there are grounds, a lightning strike to the panel could send an electricity spike to the solar controller and destroy it. A fuse or breaker would protect the solar components within the solar circuit. 
  3. Prevent a Fire – If the wiring, solar controller, or solar batteries get too hot, they can combust and start a fire. A fuse or breaker prevents too much energy from producing too much heat and shuts down the circuit. If you are concerned about fire safety, installing a fuse or breaker can be a reassurance. 

Do I need a breaker between the solar panel and controller?

Suppose the solar panel voltage is 2/3 of the max energy rating for the solar controller; you will not likely need to install a fuse or breaker between the solar panel and the solar controller.

However, it is good to add a fuse or breaker inline between the solar panel and the solar controller. 

Adding an inline breaker or fuse between the solar panel and solar controller is an intelligent move. The fuse or circuit breaker will protect all the solar components from the solar controller and solar batteries to the inverter.

The small price you pay to add either a fuse or a breaker before the solar controller can save you thousands of dollars should an energy spike occur. 

How do you fuse a solar panel?

Fusing a solar panel, such as on a caravan, is complicated. First, you need to know basic electrical wiring skills, and you will also need to know the short circuit amperage for the entire array and the max series fuse rating for the solar panels.

If the short circuit current for the array is greater than the maximum series fuse rating, you will need to add inline fuses. The max series fuse rating is located on the sticker attached to the solar panel. 

Why would you need a fuse? In the case of a short circuit, in a string of panels, the energy from the other panels would naturally seek the path of the least resistance and flow through the short into the defective panel.

That would cause a significant build-up of energy in the panel, which could lead to a fire. 

Fuses and Max Fuse Rating

Any fuse added to the solar panel would need to remain at the same amperage as the rating for the maximum series fuse rating. For example, if the maximum series fuse rating is 15 amps, any fuse you add would need to be 15 amps. 

If the maximum array amp is less than the maximum series fuse amperage, then fusing is not needed. In addition, the diodes inside the solar panel would prevent most short circuits from occurring or damaging the solar panel. 

It is inexpensive to use an electrician or solar contractor to fuse your panels, and it is much safer. 

What size fuse is required for a 12-volt 100-watt solar panel?

A 10 amp fuse is generally what you would need for a 100-watt solar panel. The actually recommended amperage for a fuse for any solar panel will be listed on the sticker attached to the solar panel.

Whatever that recommendation is, it is the size of the fuse you should use. 

Which is better, a fuse or a circuit breaker?

Generally, a circuit breaker is the better choice simply because an electrical issue will trip a circuit breaker, whereas, with a fuse, the fuse blows and is destroyed.

What that means is that you would need to replace the fuse. If you do not have an extra fuse, then the panel will not be able to send a charge to your devices or batteries.

A circuit breaker is an easy fix. Once a circuit breaker trips, you turn it back on by flicking the switch. As you flick the switch, the circuit is restored, and power continues to flow. 

There are some situations where the circuit breaker would need replacing, but those are rare and generally involve replacing the circuit breaker with a higher volume amp breaker. 

Also, the application may change, which is a better choice. If your solar panel is attached to a home, a circuit breaker is easier to manage. If your solar panel is attached to a caravan, a fuse would be easier to manage. 

Sources

Solar Panel Setup FAQ

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