If you currently possess a solar panel, chances are you have come across the term called short circuit current. You may also hear people measure the short circuit current of solar panels. So what is it and how do you measure it in a correct way?
If you connect both ends of your solar panel you will get a short circuit connection. Now put your solar panel under light and take a clamp-on meter. Set it to DC amps and use it on the wire you just connected. And soon you will have a reading and that exactly is the short circuit current of your panel.
When you connect both ends of your panel and create a short circuit connection what ends up happening is the voltage across your solar cells become zero. Short circuit current is actually the largest amount of current that can be drawn out of your panel. So it’s quite important to measure it for safety purposes.
In the following article, we will be discussing what short circuit current is, why you should measure short circuit current, the equipment you need for measuring and how to choose them, a step-by-step guide on measuring short circuit current, and more.
Table of Contents
What is Short Circuit Current in Solar Panel?
This is what you probably asked when you heard about this term? So what exactly is Short Circuit Current? Well to know that first, we have to understand what a short circuit is.
To put it simply let’s say you have a circuit and from the power, source electricity flows around it. We all know in a normal circuit this electricity encounters resistance like batteries, bulbs, etc. Now in a short circuit, you have very low resistance which in turn makes current very high.
Now take your solar panel. When you short its connection there is no resistance like a battery in between. Now when your Solar Panel gets to light it produces electricity and you get a short circuit current.
There is various math on how short circuit currents work. But here are some key things on which the Short circuit depends:
- Solar Cell’s Area
- The Amount of Photon aka Light Particles (Received from Sunlight)
- Spectrum of the Light that Hits the Panel
- The Reflection and Absorption property of Panel
- Probability of Collection
But you don’t need to worry about all of this since your panel manufacturer will take care of this. But what you need to care about is if your Solar Panel is in tip-top condition so it doesn’t produce a low short circuit current. To learn more about low short circuit current issues and fixes be sure to check out this article.
Is Measuring Solar Panel Short Circuit Current Safe?
First of all, if you are a complete beginner and have no experience with electronics it’s highly recommended that first, you use low voltage panels for measuring solar panel Short Circuit Current.
Now that out of the way, it depends upon which type of system of which you want to measure the Short Circuit Current. If it’s a full-blown solar array then stop and don’t even attempt to measure short circuit current. And if it’s a Single Panel you can do it without worry.
Now you may ask will the short circuit harm your panel? The answer is no, shorting connection won’t harm your panel since your panel will most likely be able to handle it if it was made by a good manufacturer. Commercial solar cells have 28 mA/sq.cm to 32mA/sq.cm short circuit current. But here are a couple of things you have to know about for added safety
Don’t leave your panel short for a long duration. Short Circuit is not a natural situation and is only done for short circuit analysis. Get rid of the short circuit as soon as you finished your tests.
Be careful of Radiation and Temperature. Most solar module can take 1000 W/sq.cm radiation. Be sure your weather is compatible. And always avoid high temperatures. Semiconductors are affected by temperature. And in high temperatures, the current carrying capacity of the module goes down and problems may occur. 59 Degrees to 95 Degree is a good range for Solar Panel.
Why should you measure Solar Panel Short Circuit Current?
Now a natural question comes in? Why do I measure Short Circuit Current? Well, the answer is very simple. If you take a look at the back of your panel you’ll spot Short Circuit Current Rating. Now, this indicates how much fault current your system can withstand. And you’d want to make sure you have proper protection.
First of all, Short Circuit is a dangerous situation. And it can occur in a fully functional system with a battery and other things. That’s why you install Fuse or Circuit Breakers. Now let’s say your Panel’s short circuit current can’t be handled by Circuit Breaker.
Well, you got yourself in a pretty nasty situation. To prevent this dangerous situation you have to make sure what your short circuit current is and using that install proper safety protocols.
That’s why it’s recommended that you know what short circuit current your panel is producing. Not only will you ensure safety but also be in compliance with NEC (National Electric Code)
Equipment You Need to Measure Short Circuit Current in Solar Panel
Here is the list of things you need to ensure for an ideal measurement situation:
- A Good Clamp Meter: You would need a decent clamp-on meter for correct measurement. It’s pretty self-explanatory.
- A Single Working Solar Panel: Make sure your solar panel is not damaged in any way. Double-check the MC4 connectors to make sure it is not loose.
- Ideal Environment: The measurement should be done of direct sunlight. The weather should not be extreme and there should be nothing that can shade your panel.
- Clean Equipment: You don’t want materials to fall into your panel plummeting Short Circuit Current Reading. Be sure to clean your panel and Clamp Meter.
- A Cardboard Cover: A Small Cardboard Cover the size of a single solar cell in your panel. You’d need this for a crucial test during the measurement.
How to Measure the Short Circuit Current of A Solar Panel:
Before we proceed with the step-by-step guide make sure you have sufficient knowledge regarding Short Circuit Current. (Which you’ll have if you have read the previous section).
Now that we are clear let’s begin
- Step 1: Take your Solar Panel and Make Sure it is clean. Clean it if you see some weird material accumulated in it.
- Step 2: Put your Solar Panel in a nice place where no shade from trees or roof ruins its current production.
- Step 3: Your Solar Panel should ideally face the sun in a way that the panel is perpendicular to sunlight. By doing this you ensure a perfect result.
- Step 4: Take both cables of the panel and connect them with each other. You may hear a little spark but don’t be afraid.
- Step 5: Make sure there are no magnets nearby that will mess up the reading.
- Step 6: Take your clamp meter and set the dial to DC Amps. Don’t mess it up or you’d have the wrong reading.
- Step 7: Put the clamps on the connected wire. And now the clamp meter will measure the Short Circuit Current via detecting the magnetic field produced by the wire
- Step 8: It’s is optional but doing so can detect a huge issue. Take a small cardboard cover then begin to cover each cell of the panel.
- Step 9: If one cell is covered the short circuit current should drop. If you covered one cell but the current is not dropping it is a sign that your solar panel is broken and need replacement or repair
- Step 10: Once the testing is done disconnect the cables of the solar panel
Things to Consider before buying the Best Clamp Meter
The clamp meter is the most crucial piece while measuring short circuit current. And for measurement, you need to choose the best clamp meter. So below we will be providing some things you need to know before you buy one yourself.
First, there are two types of clamp meters: DC ones and AC ones. Solar Panel produces DC current so it’s a must to choose DC clamp. Also quick fact the DC ones can also measure AC current plus it uses a hall effect sensor for good measurement so It’s a win-win situation.
Now to ensure good safety be sure to buy a good clamp meter with decent quality material. Remember higher overall voltage, current, and resistance = more safety. Since you’ll be using it for small tasks (solar panel), a lower resistance limit is fine.
Some clamp meter has a backlit screen. Since you are working in a sunny environment you don’t need this feature. And finally to ampere rating. You’ll be working on a small project like solar panels. That’s why a 300 A to 400 A rating will suffice.
But it is to be noted that if you are planning to use a clamp meter on high-end dangerous systems, then get one with a high Amp, Resistance, and Voltage Rating for more safety.
Short Circuit Current analysis is an important part if you own a solar panel and want to ensure that your fuse, circuit breaker, or other safety mechanism doesn’t fail.
Measuring the short circuit current of your average day-to-day panel is quite is easy and can be done yourself. But remember I won’t recommend you to measure high voltage solar array.
The key things to keep in mind are to make sure you are using a good panel and clamp meter. Put your panel perpendicular to the sunlight, short the two cables safely. Then put your clamp meter on DC Amp setting and measure your short circuit current. And that’s how you measure the short circuit current of a simple solar panel quite easily.