How To Test Solar Panels In 4 Simple Steps – A Step-By-Step Guide


Jack Ayre

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It’s often difficult to tell if you have an issue with your solar panels and they are not producing effectively. Unless you are regularly monitoring their performance, you will only tend to notice an issue when an overinflated electricity bill arrives. Because of this, it’s a good idea to do regular preventive maintenance on your solar system.

In this article, we discuss how to test solar panels so you can better monitor your setup. We cover the common problems you might encounter and give you tips on ensuring your panels are working. Let’s get to it!

Why You Should Test Solar Panels

Testing your solar panels has its advantages. First, you can determine their actual output.

The efficiency of your system isn’t constant. Manufacturers will tell you the maximum capacity, however, the weather, roof pitch, and other factors can affect how much electricity you generate.

If you test your solar panels, you can have a clear idea of how much you can expect to save for the month. What’s more, it’ll help you identify an issue with your setup.

With regular testing, you can detect drops in energy production, which can be a sign of broken or faulty components. It can alert you if you need to contact maintenance, and even save you money from replacing parts!

Signs You Need to Test Your Solar Panels

These are indicators that you have to test your solar panels.

  • There’s a lag in performance, and the power output lessened.
  • Your electricity bill is high.
  • The mount or frame looks bent.
  • Damage to the wiring is visible.
  • The inverter is showing an error message.

How to Test Solar Panels Using a Multimeter

Solar panels are prone to breaking because they’re exposed to extreme temperatures.

One way to test them is with a multimeter. It can measure current, resistance, and voltage accurately.

Selecting a Multimeter

You can get multimeters in analogue or digital form. The main difference is the display.

Analogues are cheaper and more durable, but it may be hard to read the results. This is because it has an old-fashioned scale and needle pointer.

Digital multimeters are more expensive but precise and easier to read. They can also have settings that an analogue multimeter doesn’t have. Both will work for the tests you’ll do on a solar panel!

4 Steps to Testing a Solar Panel With Multimeter

Here’s how to test your solar panel with a multimeter.

1. Follow the Safety Precautions

Before you begin, always ensure you’re wearing insulated gloves. Check the multimeter for broken wires, and only use the machine if it’s completely dry.

Never connect the tips of the two probes as this could cause it to short circuit!

2. Measure the Voltage

To measure the voltage, turn the device on and set the selection knob on the multimeter to DC voltage.

After this, place the black probe on the negative terminal of the solar panel. Meanwhile, connect the red probe to the positive terminal.

Remember, the black probe always goes into the COM slot. On the other hand, the red probe fits into the V/Ω/Hz slot.

Next, bring your solar panel into the sun and face it towards the south for the best results. Once you get a reading, compare it to the voltage (Voc) on the back of the panel.

If the values are close, your solar panel is in good condition. However, if they don’t match, it’s a sign that your panel is dirty or damaged. A wiring issue is possible as well.

3. Take Note of the Resistance

Resistance is an indicator of the opposition to the flow of the electric current.

To do it, turn the knob to the ohms or Ω setting. Once set, connect the probes to the resistor leads and check for the reading.

Avoid holding both leads because your skin can affect the result.

If the ohms value is between zero and one, your solar panel is functioning well. A measurement of one and above means your solar panel’s cord is broken!

4. Check the Current

Current is the amount of electricity running through the circuit. It’s vital to measure this to see if there’s a parasitic draw on your battery.

A parasitic draw is an electrical component that uses electricity even if your solar panel is off. It can cause low voltage or a dead battery.

To check for the current, turn the selection knob to the amp setting. Connect the multimeter’s probes to the battery cable, and take note of the value when your panel gets exposed to sunlight.

Finally, compare the reading to the Isc value on the back of your solar panel. If the reading is far from the specifications, it’s a sign you have a short circuit.

Testing for Solar Panel Watts

The average solar panel makes 250 to 450 watts per hour. That’s 750 to 850 kilowatt-hours per year! Naturally, anything below this range means there’s an issue with the system.

After taking measurements with a multimeter, you can compute for watts using the following formula:

Watts = Volts x Current in Amps

Aside from this method, you can measure watts using a solar charge controller. Some of these devices can even connect to your phone. As a bonus, it can track and control your output!

How to Use a Solar Charge Controller for Measuring Watts

In off-grid setups, the solar charge controller is the link between the solar panel and the battery.

In addition to measuring watts, it can extend the lifespan of your batteries. The controller does this by detecting if your panels are producing more energy than your battery can handle. It then makes adjustments accordingly.

So how do you set it up?

You can connect it to the battery by taking your wire and inserting it into the port of the charge controller. Once that’s done, you can tighten it with a screw.

Next, attach the wire to the battery according to the positive and negative poles. The solar controller should show the battery capacity in its display.

Finally, connect the solar controller to the solar panels using the same method. Be aware of sparks that may happen upon attachment. Don’t worry, this is normal.

You can now observe the wattage indicated on the controller!

Tips for Testing Solar Panels

If you encounter an issue with the values during your test, you may want to check the following:

  • The solar panel should be clean and free from dust.
  • Ensure you do your test in full sunlight without any obstructions.
  • Angle the solar panel towards the sun at the correct pitch.
  • If the weather is bad, redo the test on a clearer day.

Other Common Issues With Solar Systems (And How to Test Them)

The panels aren’t the only components you have to test to make sure your system is in good condition.

Here are other parts to consider.

1. The Inverter

The inverter is a part of your setup that you should always pay attention to. It needs regular maintenance, and it only lasts for five to seven years. This is because the inverter is prone to voltage spikes and overheating.

Always check your inverter for a green light. An orange or red light indicates you have a broken capacitor or a short circuit.

In the case of the latter, you can try restarting the device. If it doesn’t turn back on, it’s time to call the professionals.

2. MC4 Connectors

After a while, your MC4 connectors can harden or lose conductivity and may need replacement. It can cause an uneven flow of charges, which may lead to overheating.

Additionally, if the MC4 has improperly locked, it can raise the inlet moisture and trip the inverter.

To avoid these instances, you should test the MC4’s contact resistance, insulation resistance, and lock.

3. The Battery

Like the panels, the lifespan of your battery is also affected by extreme weather.

Its state of charge is an indicator of the condition it’s in since it affects the amount of energy a battery can hold. You should monitor it because of this reason.

Luckily, a multimeter can do the job! All you have to do is measure the voltage and convert the value.

Don’t forget to take the SOC reading when the battery isn’t receiving energy from the solar panels. It can give you more accurate results.

Solar Panel Testing FAQs

1. What Are the Signs My Solar Panel Needs Maintenance?

If your electricity bill or SEG payment is skyrocketing, it’s a sign that your solar panel needs maintenance.

Moreover, even if there’s no visible issue, it’s best if you test your solar panels yearly. Doing this makes sure your electricity generation is at an optimum level.

2. I Found a Problem With My Solar Panels. What Should I Do?

If you encounter a problem, you should immediately contact your installer for a checkup.

You can also get professionals to conduct preventive maintenance so you don’t have to do the tests. The inspectors can identify an issue with your PV system, replace faulty panels, and fix your solar inverter as well!

3. What Factors Can Affect Solar Panel Output?

When you conduct a test on your solar panels, several factors can affect the reading. The weather, pitch, and panel direction may lower your system’s productivity.

What’s more, high temperatures and overheating can make your solar panels less efficient.

Due to these, you should always do your test under the right environmental conditions!

4. Where Can I Get Information About My Solar Panel’s Performance?

The best part about having reliable installers is they give you easy-to-understand data. This data tells you how your solar panels should be performing.

With transparent information, you can contact customer service if your system isn’t working as it should.

Solar Panel Testing Conclusions

In conclusion, it’s vital to learn how to test your solar panels to ensure they’re in working condition. This’ll help you avoid costly damages, and save you money in the long run.

To test your system, you can use a multimeter to measure current, voltage, and resistance. After this, you can compute the power in watts and determine if there’s a problem. Checking the inverter, MC4 connectors, and battery is important as well.

Don’t forget to take safety precautions like checking for physical damage and using insulated gloves. Lastly, if you find or suspect an issue with your solar panels, contact your installer immediately!


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Cut your electricity bills

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With a new solar setup, including a solar battery, you can drastically reduce your electricity bill


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Born in North West England, Jack kicked off his career in the insurance arena, dealing with claims for three years. Always up for a challenge, Jack leapt out of his comfort zone and embarked upon 5 years of excitement with the military.

Working for the Ministry of Defence, Jack specialised in counter-terrorism which took him to places such as Dubai, Oman, Iraq, Norway and Bahrain. During this period he worked with various Governments implementing strategic operations to prevent terrorism.

After travelling around various countries Jack increasingly came across various forms of solar from large solar farms to domestic solar panels. From here Jack took a keen interest in all things solar and started reading about the technological capabilities with a view to entering the industry after his career in the Ministry of Defence.

Once home after 5 fruitful years, Jack had 3 months leave in which he immersed himself in a solar crash course and got applying for jobs within the solar sector. He came across ESE Solar, a long-established forward-thinking company whose head office was only a stone’s throw away from him. He picked up the phone to see if there were any vacancies and within a week had a successful interview and obtained a full-time job, starting in the technical team.

Within the first few months, Jack onboarded in various online courses during work and social hours to speed up his knowledge of all things solar. Due to his strong work ethic and thirst for knowledge Jack was promoted to Head of Technical at ESE Solar. He currently leads the team and oversees the product development of new technologies within the company alongside assisting where necessary on their maintenance department.

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