Solar panel fuse or breaker? (Circuit Setup + Why)

Are you wondering if you need a fuse or breaker for your solar panel? If you are, you may also wonder 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 to help you make a more informed decision about handling excess energy flow from your solar panel

Circuit Brekaer On A Wall
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 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, adding a fuse or circuit breaker is no harm; 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 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 reassuring. 
Electrical Breaker Box. - Sol Voltaics: Solar Panel Information
Electrical Breaker Box.

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, adding a fuse or breaker inline between the solar panel and the solar controller is good. 

Adding an inline breaker or fuse between the solar panel and the 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 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 must remain at the same amperage as 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, fusing is unnecessary. 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. 

Charge Controller Wires
Charge Controller Wires

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 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 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. A circuit breaker is easier to manage if your solar panel is attached to a home. A fuse will be easier to manage if your solar panel is attached to a caravan. 

Sources

Solar Panel Setup FAQ

How long do solar panels last?

How long solar panels last depends on their quality and how well looked after. In general, though, most solar panels will last between 25 and 30 years, with the most expensive models having a life expectancy of 40–50 years. That being said, solar panels will still produce energy after this time, although their capability will have declined significantly. 

How do you set up a solar panel system?

The first step in setting up a solar system is determining how much power you need, and planning your solar system accordingly. After this, the setup is fairly straightforward;
1. Gather all the required components together; panels, inverter, batteries, cables, etc. 
2. Find a safe space in your home to house the inverter and batteries
3. Fix the panels to your roof or a stand
4. Connect the panels to your inverter or charge controller
5. Connect your inverter to your batteries

What is required for solar panel installation?

Again, the first crucial step for any solar installation is calculating your power needs. Once you’ve done this, you’ll need to purchase the appropriate components. These include;
1. Solar panels
2. Batteries
3. Inverter
4. Charge controller
5. Suitable cables
These components are typically purchased separately according to your needs, but you can purchase ready-made solar kits that have all the components you need too.

Can I set up solar panels myself?

With a bit of basic DIY and electrical knowledge, you can certainly set up solar panels yourself, especially smaller systems. The setup can become somewhat complicated for large, high-power systems that are grid-tied, though, and you may want to get assistance from a qualified electrician. 

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