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What Does the Warranty for Rated Power Mean For a Solar Panel?

Solar panels can be a significant initial investment, so it’s important to know product warranties and what they cover.

Most people assume a warranty is for product defects or faults that allows the owner to get the product repaired or replaced at no extra cost. That is right, but it is not the only thing a warranty will cover when it comes to solar panels.

A warranty for a solar panel also means a promise of performance, and it is important to understand what this means.

Solar panels are expected to produce a certain amount of power output for their rated wattage for a period of their lifetime. It is called the warranty for rated power and means what you can expect from your panel in terms of energy generation.

In other words, most solar panels’ production efficiency warranties are time-based, which means a certain degree of performance is guaranteed for only a certain number of years.

technician measuring solar panel output

Manufacturers typically guarantee that their panels will produce 90% of the panels’ rated power for the first ten years, and 80% of the panels’ rated power for the remaining 15 – 20 years.

This period is also known as the system’s “useful life” or “economic life”. It is the period of time during which the product is functioning properly without compromising its performance.

After the system’s useful life is over, the panels may continue to generate electricity but at a lower rate, since they won’t be performing at their peak.

The warranty for rated power is a crucial factor to consider when investing in solar panels. Because it is not only how much energy your system will produce but also how long it is expected to function at its best level.

If you want to reach certain financial objectives, you will need to make sure your panels will produce as much power over the decade as they did initially.

What to do if your solar panels are underperforming?

If it seems like your solar panels are not performing well as their warranty for rated power should guarantee (i.e. producing less energy than they were supposed to), it might be a good idea to have them checked by a qualified electrician.

The inefficiency of a solar PV system doesn’t always mean the problem is with the panels themselves. Instead, it might be an issue of improper installation or problems with the other components in the system.

If the problem is not caused by faulty installation or incorrect connection, it could be because there is a manufacturing defect. In this case, you should have the panels replaced by the manufacturer free of charge as per your warranty.

However, before even inviting an electrician or calling the manufacturer to make a warranty claim, you should rule out other possible causes.

A few things you should check are:

Is there any visible damage to the panels?

Check for visible signs of panel damage like cracks in glass or metal, corroded terminals, and exposed wires. Not all damage may be immediately visible to the naked eye. However, if you can see a crack or a puncture, this is a sure sign that there has been some damage.

Is the orientation of the panels correct?

Panel orientation might also be to blame for low energy production. If the panels are not facing due south (in the northern hemisphere), they might absorb less sunlight and produce lower amounts of electricity.

If you have installed your solar panels on the east or west-facing roof, they will produce much less electricity than if they were on a south-facing roof. Therefore, if you are not getting the output you expected, check your panel orientation to see if it matches where the sun rises and sets.

Is there any shade to be concerned about?

One common reason for low output is shade on the solar panels. Shading happens when leaves, branches, or other obstacles grow nearby and cast shadows on the panels. Make sure there are no trees or buildings nearby that could cast shadows over your solar panels.

Also, shading conditions may vary throughout the year. For instance, in winter there might be less leaf cover on trees, and shading conditions will not be as bad compared to the summer when leaves grow and block sunlight.

Shading can also be due to dirt and debris built up on the panels. A dirty panel can reduce the amount of energy it makes by up to 40%. There might be dust, bird droppings, leaves, or other things that can accumulate on your panels preventing sunlight from reaching panels. 

Are the electrical connections clean?

You should inspect the electrical connections, exposed wires, and junction boxes for any signs of corrosion.

If there is corrosion anywhere in your system it will be causing a drop in efficiency and your panels won’t produce as much energy. When doing any type of inspection on your system always disconnect the main supply before touching anything. Electrical problems can be dangerous, so be cautious when inspecting your system.

If you aren’t sure what you are looking for or doing, it is best to have your PV system inspected by a qualified electrician.

Inspect the wiring for defects. In most cases, wiring defects are very hard to notice since it is the last thing people think of looking at.

However, if you are experiencing low output from your panels, it may be due to wiring defects that need to be repaired or replaced. Check all connections and make sure there are no loose wires or corrosion.

Is the inverter compatible with your solar panels?

Inverter selection is extremely important. A good inverter will manage power flow to and from your solar panels, converting DC (direct current) into AC (alternating current) power needed for the house to operate.

If your inverter is not compatible with your solar panels it will be unable to manage the flow of electricity correctly, resulting in loss of power/ production.

Inverter compatibility is dependent on various factors such as voltage, current, and frequency. In other words, the inverters you install must be compatible with the panels you purchase.

It is critical to properly size your system in order to determine the best voltage and wattage for you. If you have a 24-volt battery bank, a 24-volt inverter is unquestionably the best option. However, if you have a 24-volt system and use a 12-volt inverter, it will result in poor battery charging and discharging performance.

All of these factors can cause a reduction in power production and efficiency if not given the proper attention to detail!

Is the inverter working properly?

Your inverter is the device that converts direct current (DC) produced by your panels into alternating current (AC), which you can use in your home. Therefore, if your inverter is not working properly it might be the cause of underperformance issues with your solar panels.

Common inverter problems that can cause lower energy production are:

  • The inverter has a defective component.
  • The inverter is overheating.
  • The inverter is not programmed to work with your backup generator.
  • The inverter needs a software upgrade.
  • Your battery system needs to be rewired so it can work with the new inverter.

Is there any fault with the battery system?

If you have a battery system to store excess energy for later use, you should check the battery system and make sure it is working properly. Low or lower-than-expected output from your solar panels could be due to a faulty battery system.

The batteries might need maintenance, which may include cleaning and replacing the electrolyte solution. If they aren’t cleaned regularly their lifespan will decrease significantly over time.

If you haven’t had any issues with your battery bank, but still have low power, it might be due to a faulty charge controller that isn’t working properly.

Is there any fault with the charge controller?

The charge controller is responsible for taking the energy from your solar panels and charging your batteries. A charge controller that is not working properly will decrease your battery charging, causing a loss of power.

Charge controller problems are very common and can include:

  • The charge controller has an internal short.
  • The batteries are not hooked up properly to the charge controller.
  • The charge controller has a defective component.

There may also be a problem with the charge controller’s programming that needs to be fixed. It is very important that your charge controller works properly with your inverter because it will prevent overcharging and undercharging of your batteries.

Check the array temperature

If you live in a very hot climate, your panels may be producing less energy simply because they are running too hot. The panels’ performance will gradually decrease as the temperature rises above 25 degrees Celsius.

Unfortunately, there is not much you can do to lower the temperature, but it might be worth knowing that the hotter it is, the less efficient your panels are. So it may be a contributing factor if you are experiencing low output.

In which cases do the panel manufacturers offer coverage for the power output decrease?

In most cases, if the decrease in rated power output is due to manufacturing issues with the PV module, it should be covered by warranty. Before offering a replacement, solar panel manufacturers will want to do their own tests. Therefore, they may ask you to bring your system to them for tests.

As we have seen, there are many possible causes of low power output. Therefore you need to know for sure that the problem is really sourcing from the solar panels by themselves.

So unless you actually make the effort to go through the list of possible problems with your system, you will never know for sure if the problem really lies with your solar panels.

Misuse & Improper maintenance

Most manufacturer warranties do not cover defects or malfunctions caused by misuse, abuse, or improper maintenance, failure to follow operating instructions or use with equipment not intended for that purpose.

You as the owner have a responsibility to properly maintain your system and take good care of it. For example, you should regularly inspect the panels, clean them if necessary and check for any broken parts.

Similar to most other electronics, if you have opened the panels or had any work carried out on them, you will invalidate your warranty. Neither you nor a third party other than an authorized dealer should carry out any work on the system.

Therefore, don’t even unscrew a single screw or you might end up breaking the warranty. Warranty services try their best to find out what kind of alterations you have tried to make to your system so that they can refuse to repair it.

So the warranty is unlikely to cover damage caused by unauthorized alteration, modification, or repair of the product.

Modules that have been exposed to high levels of salt, extreme moisture, or high temperatures will not be covered by most solar panel manufacturers. Therefore, expect your warranty not to cover damage from weathering or overheating.

Natural disasters

Natural disasters such as earthquakes, lightning strikes, floods, hail, and hurricanes can damage your solar panels. These types of damages are normally not covered by a manufacturer’s warranty.

In such a case, you need to work with your homeowner’s insurance company to determine if the damage is covered. Although most homeowner’s insurance policies do cover solar systems, for natural disasters you may need an additional rider added to your policy. Talk to your insurance agent for more details on coverage.

Your insurance company may require that the installation of your system be inspected by a professional engineer before covering damages caused by natural disasters such as hurricanes.

Manufacturing mistakes

Manufacturing mistakes are the only issues that most manufacturers will cover under their warranty.

The manufacturer warranty for the power output will normally cover manufacturing defects such as broken cells, busbar, and fuse defects. In addition, the warranty will also provide coverage for module power degradation that occurred earlier guaranteed by the manufacturer.

If your solar panel manufacturer also offers installation services, you should take advantage of this by having them install your solar panels. This will ensure that all the systems are properly connected and installed to function well. It will also prevent the company from claiming you have caused the damage by not following their installation instructions.

There are shipping damages sometimes occur and are covered by the manufacturer warranty. If you have received your system with broken parts take pictures of the damage and contact the manufacturer right away to report it.