We have controllers for the safety of solar panels, but why do we need fuses or breakers? These act as protective devices for solar panels, but which one to choose is a question. Today in this blog let us understand the functioning and differences between both of them.
Solar Panel Fuse Vs Breaker
Depending upon the solar setup if you are looking for an option that responds faster you can prefer a fuse. But when you want a durable option that resets itself and reuses again go for a breaker.
Fuses react quickly in case of fire or short circuit but once blown they can no longer work so they need to be replaced. As they are a bit cheaper you can buy them in bulk and stack them.
Breakers trip in case of a short circuit or overload, and they can be reset with a single button. There is no need for wiring or replacing very often so the maintenance will be easy. However, they are a bit expensive upfront when compared to fuses.
| Feature | Fuse | Breaker |
| What is it? | It is a device to protect overcurrent for solar panels and modules. | It is a switch that resets in a circuit in case of a short circuit or overcurrent. |
| Working | Once the overcurrent flow passes, the cartilage melts the whole fuse. It needs to be replaced | Their electromagnetic switch opens up or resets when overload happens. It can be reused |
| Installation | Placed in line within a circuit or can be installed in a fuse holder | They are hanged on the panel with some support |
| Wiring | Does not require additional wiring | Do require wiring and support |
| Reaction time | 1-2 secs for the melting to start | 2 to 5 seconds as it is a thermal process |
| Replacement | For every fusing occurrence, they blow so they need to be replaced | PV panels which often have electric arcs may affect breakers |
| Cost | Fuse is cheaper | Bit costlier when compared |
| Parameters | Sized using Amperage and voltage | Assessed using Amperage, voltage, and capacity |
Installing a fuse or breaker is a good idea because they save the entire solar panel system from the following conditions:
- If the voltage of the solar panel is more than even the controller cannot handle
- Natural disasters like lightning can increase spike in electricity and may destroy the entire system
- Sometimes writing may spark fire due to excessive heat
- In case of faulty equipment, the circuit shows wrong readings which leads to internal damage
- When short circuits occur
How do you Fuse Solar Panels?
For fusing a solar panel you need to have knowledge of basic wiring equipment and know a couple of things like amperage of whole solar equipment and maximum series fuse rating.
The current at which the panel can safely function is called the Maximum Fuse Rating. You can find the maximum series rating on the label on the solar panel. If the short circuit electricity of your solar array is higher than the max fuse rating then you need to additionally include inline fuses.
The fuse is installed on the string of solar panels on its positive side, within the fuse holder.
Also See: Is it Dangerous If Circuit Breaker Keeps Tripping?
What Type/Size of Fuse You Need?
Types of Fuse: The common types are Photovoltaic fuses and Midget fuses.
1. PV fuse is made up to protect panels from over currents or reverse currents the system generates. They are made up of a fuse link surrounded by cartridges to withstand high temperatures.
Again the PV fuse has two designs – fast blow and slow blow fuse. Fast blow as the name indicates will melt down as soon as overcurrent is passed, whereas slow blow can retain small surges.
2. Midget fuses are made up of a conductive substance made with metal alloy with a low melting point to cope with overcurrent. These are smaller when compared to PV fuses.
Size of Fuse: To determine the size of the fuse you need to understand the current rating of the circuit. As the fuse avoids excessive current flow, you need to select a fuse a bit higher than the maximum current. For example, if you expect 10 amps maximum current in the circuit, you need to choose 12 amps fuse for better results.
In another case suppose you have 2 solar panels of 200 watts and 12 volt solar system, which means total wattage is 400 watts. So the current would be 400W/12v = 33.33 amperes.
So a bit more than the derived value of a 40-amp fuse would be suitable. In most cases, a 25% higher rate than wattage would suffice the need.
For more details, check out the Solar Panel Fuse Calculator: How to Determine the Required Fuse Size.
What can be a Solar Panel Fuse Location?
These fuses are installed in places where they protect components such as panels, batteries, and cables. While using fuses, note these points as well.
- You need a breaker between the panel and the controller
- They are places in the link between the combiner and charge controller
- A charge controller and battery bank
- At the spot where cables are there to safeguard wires and modules
- Placed at the inverter and battery
When you need to decide between a fuse or breaker for the solar panel, the fuse responds immediately but needs to be changed every time. It may look like the fuse works faster but the breaker’s delay avoids unwanted tripping. It is up to you to decide which one you choose to protect the solar assets. For more information visit our website.
Recommended: Do I Need A Fuse Between Battery And Inverter
