The Solar Power Expert Blog

Different Types of Fuses For Solar Systems

by Chris - August 19th, 2011.
Filed under: Equipment. Tagged as: , , , , , , , .

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The fuse is your friend.” I used run a shop in Seattle building custom electric bicycles and I would always tell that to my customers. That’s just as true for solar systems as it is for electric bicycles, automobiles, or any electric circuit for that matter. A fuse is essentially a precisely sized wire that ‘blows’ or melts when the current running through it exceeds the fuses rating. It’s an intentionally designed weak link in your circuit, so that if any problems occur, the fuse will sacrifice itself to protect the rest of your circuit elements.

Electrical Fuses Types

The three most common electrical fuse types that you’ll run across would be the ATO/ATC ‘blade’ fuses for cars, mini blade fuses, and glass fuses. Glass fuses used to be much more common, but today a good selection can only be found in specialty electronics stores like Radio Shack. The automotive industry have adopted the ATO/ATC blade and mini-blade automotive fuse types almost exclusively.

Where to Buy Fuses

For this reason, I always recommend people integrate an ATO/ATC automotive fuse holder into their solar system and keep a good blade fuse set on hand. While your at it, try to use a waterproof fuse holder. They are often no more expensive and a waterproof fuse holder will prevent a lot of corrosion issues (which can be hard to debug). You can use either the blade or mini-blade type. However, the ‘regular’ blade type is much more popular. I’ve seen these fuses sold at virtually every convenience store and even many grocery stores such as Safeway, Albertsons, and Fred Meyer will sell these automotive fuse types.

Why the emphasis on wide availability? Because if people can’t get their hands on the right fuse, they tend to do stupid things. I’ve seen many people replace a blown fuse with a paper clip and then they’re surprised when the expensive piece of electronics the fuse was designed to protect blows up. The key to using fuses is availability. The key to availability is to use the most common types available.

Where To Use Fuses

I’m of the opinion that fuses should be used on every circuit. Even circuits carrying less than 1 amp should be fused. In that case, you’ll probably need to resort to an in-line glass fuse holder and use glass fuses.

The reason to use fuses whenever possible is because electricity is invisible, for the most part. Large amperage circuits may make obvious signs of damage when they misbehave, but not always. Low amperage circuits are much more forgiving and may short for hours before something breaks. However, you won’t know anything is wrong because you can’t see anything is wrong. A blown fuse is often the only indication you’ll get that something is wrong with your circuit.

12 Volt Fuse Block

For a full solar system, you’ll probably want to use a 12 volt fuse block instead of several individual fuse holders. If your system ties together indoors, you can use a motorcycle fuse block. However, if your system ties together on the outside of a building, you’ll definately want to use a marine fuse block to prevent corrosion damage from water and oxidation. Either way, it is always a good idea to smear some anti oxidant compound on the fuse terminals to prevent corrosion. I’ve seen many circuits stop functioning simply due to oxidation of the fuse. All I had to do to ‘fix’ the circuit was pull out the fuse, scrape the blades with a knife, and reinsert it. However, these types of problems can be notoriously hard to debug without experience and anti oxidant compound can prevent it from even occurring.

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