How to choose and use the right wires with your solar system.
Solar wire types (also known as solar panel wire and pv wire) refers to the type of wires used to connect your solar panels with the rest of your photovoltaic system.
Choosing the right wire for your solar energy system is critical to it's functioning properly and remaining undamaged. If you get this wrong and choose a pv wire too small for your pv system, your battery bank may not charge fully and as a result your appliances might not work as well or at full power.
Electrical wire (which is the same exact thing as solar panel wire) is categorized mainly based on it's conductor type. If it has a single metal wire core, it's a single stranded conductor and if it has a multiple wire core, it's a multi stranded conductor. These are the two basic wire types.
The difference between a single stranded conductor and a multi stranded conductor is that the multi stranded performs better in continuous vibration environments such as mobile applications in cars, boats, planes and trains.
The one strand conductor type wire is most commonly used in domestic wiring and should be okay for your solar system, however if your area is prone to consistent and extremely high winds, you may want to consider wire types with a multi stranded conductor as it is more flexible thus more durable.
The wires used in solar systems are rated by their Amps. This is the maximum amount of amps that can travel through that wire and this rating must not be exceeded.
Basically, the higher the current (amps) your solar system is rated at, the thicker the pv wire has to be. If your system produces 7 amps, you will need 7 amp wire (actually it's better to go a little higher like 9 or 10 amp wire, just to make sure you can handle the current).
If you mess up and use wire rated at less amps than your solar system produces, the voltage will drop, your solar panel wire will most likely heat up and eventually may even catch fire causing damage to your solar energy system and your home. You can learn more about staying safe while working with solar power by clicking here to go to the Solar Safety section of our website.
Think of your electrical wire like a plumbing pipe. If there is too much water pressure (amps) flowing through it, it will burst. Therefore you would need to get a bigger pipe (wire) that can handle the pressure (amps) produced by your system.
Thicker pv wire costs more than thinner pv wire because it can handle more amps. When choosing the thickness of your wire, you can go one of two ways. A little thicker for safety or just thick enough but vulnerable to sudden power surge.
A great way to go about choosing the wire thickness for your solar system is to buy solar panel wire big enough to cope with the biggest current (amp) drawing appliance you have and using that wire for all the other runs to the AC breaker panel. Use a wire sizing calculator for solar arrays that will figure out the size of wire you need.
Along with having to use pv wire rated at the right amps, you must also take into account the length of your solar wire. By this we mean that if your pv wire is longer than average and connected to a high current appliance, you will need wire with more (higher) amps. Otherwise, there may be a voltage drop and a fire.
For example: If you had a 20 amp appliance and you used a 20 amp wire of considerable length, you would be at risk of a voltage drop. To prevent this from happening increase the size of the pv wire to at least a 35% margin, so for the above example, use 27-30 amp wire to be safe.
The longer your wire is, the higher the amp rating on your wire needs to be, so don't be shy to go a little thicker in the name of safety.
Also, using thicker wire can insure that potentially high current (amp) appliances bought in the future will be more likely to handle the current. There is no harm in preparing for the future now, especially if it's going to save you having to upgrade to thicker wires later.
Here's an example to illustrate how length affects amp rating.
Let's say your solar panels / battery bank produced 7 amps and you were using a wire length of 4.6m. This is starting to get lengthy, so add a 35% safety margin which is:
7 + (35% of 7) = 9.45 amps
Therefore, you would need 10 amp wire.
If you run pv wire that's even longer, you can use the chart below to determine the necessary wire thickness based on amp rating and wire length.
Here is a guide to choosing the right wire gauge (thickness) for your amp rating plus your wire length.
To determine the size of solar wire needed, just look at the AMPS in the left column and select the amp rating of your solar system. Next follow the same row over to the approximate length of pv wire you will be using. Then, follow the column up to the yellow box at the top which will be the AWG number wire you'll need. AWG is a system of labeling wires that has been used for many years in the USA. AWG numbers get smaller, as the wire length increases.
One important thing to note is that, while all wire used for individual runs from the breaker panel to the appliances must be able to handle the amps of that appliance, the wire from the battery to the rest of your photovoltaic components must be able to handle the total amps of all the individual runs, plus at least 35% more. You can learn more about the various photovoltaic components needed in a solar energy system by clicking here to go to the Photovoltaic Components section of our website.
Also, keep in mind that it's better and much more affordable to try and use solar wires that are shorter in length rather than to have to buy very thick (and expensive) wire to compensate for unnecessary length.
Please consult with a certified electrician to verify that you have chosen the right solar wire types for your entire solar power system before connecting any wires.
If you stick to these rules and basic safety pre-cautions to choosing the right solar wire type and thickness, you will definitely improve your effectiveness and efficiency as well as reduce your chances of causing damage to your solar energy system.
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