Warranties and guarantees are as important as the pricing for most homeowners and that is why most homeowners ask the following questions:

1. What if my roof leaks?

2. What if the solar panels go bad?

3. What if the inverter goes bad?

4. Who will fix my system if it goes bad?

These are all good questions and you will find your answers bellow:

1. Solar Panel (modules) Warranty:


Solar panels are an important part of a solar power systems, but they are not the only component. In this article we are focusing on the solar panels (modules). The following are some of the important factors when considering a solar panel for your project?

  • Solar Panel dimensions (W X H X D)
  • Solar Panel Efficiency
  • Solar Panel Annual Degradation
  • Product warranty
  • Output warranty
  • Certifications such as UL and IEC
  • The stability of the manufacturer

In this article, we would like to discuss the product warranties vs output warranties.

What is a solar panel warranty?

The solar panel warranty has a binary logic behind it! Your panel is either working or not working. If it is not working, then the solar panel manufacturer must replace it under the warranty and pay for the workmanship. There are some exceptions such as intentional damages. If one or more of your solar panels in your system do not work, then it may affect your entire system’s performance depending on the type of inverter that is used for your project. Hence, it is important to find out if your panels are working properly or not. You can use your solar monitoring system to find out if your panels are working. If one or more panels are not working properly, then you can submit your claim and the manufacturer must replace it for you as long as it is still under warranty. The term of the product warranty usually varies depending on the manufacturer. It can vary from 10 years all the way to 20 years. Sunpower offers the best product warranty.

What is a solar panel performance warranty?

The solar panel performance warranty is not a binary matter. It means a solar panel might be working, but not delivering what it should deliver in terms of KWh production (Electricity).

The KWh production of solar panels decline over time and manufacturers provide a performance warranty schedule. For instance, LG Solar Panels offer the following predictions:

1) 1st year: 98%. This mean 2% degradation (decline) in the first year

2) After 2nd year: 0.6% annual degradation (decline)

3) 83.6% for 25 years

You will find similar information for every solar panel manufacturer on their spec sheets.

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2. Solar (PV) Inverter Warranty:


Solar Inverter or PV inverter is an important part of your solar power system as it will be turing the DC (Direct Current) electricity generated by your solar system to the AC (Alternative Current). Choosing the right solar inverter is important for your system’s overall efficiency. As a result, it is extremely important for you to consider the following items at minimum when it comes to the solar inverter:

  • Type of inverter. Is it a Micro Inverter or it is a String Inverter?
  • Inverter efficiency
  • The term of the Inverter Warranty

In this article, we are talking about the importance of the inverter warranty and performance.

If your solar panels are working properly, but your inverter is not turning the DC electricity to the AC electricity for your household use, then your system is defective. In that case, you want to be covered for the repair and replacement of the defective inverters (equipment and workmanship).

The term of the inverter warranty varies depending on the manufacturers. For instance, some manufacturers such as Enphase Inverters, offer 25 years limited warranty on their inverters and some others such as SolarEdge, offer 12 years standard limited warranty. However, you can purchase extended warranty for SolarEdge inverters.

Solar panels are static items and they do not go bad that often, but the inverter is an electronic item which may go bad every few years. As a result, it just makes sense to get the longest possible warranty for your inverter.

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3. Roof Warranty

Best Roof for Solar

Roof warranty is extremely important for rooftop solar systems. Usually, installers do a roof evaluation before installing your solar system. They do that because they want to make sure that your roof withstands the solar panels for years to come or you need to do a re-roof before installing your solar power system. If your installer did not do a roof evaluation, that is a red flag.

When you install a solar power system, it will void your original roof warranty for the sections that you install the solar system. With that in mind, it is important to get a good roof warranty from your solar installer, but still warranties are as good as the companies behind them. This means you must find a company who has installed solar panels on roof materials similar to yours.

You need to read the roof warranty section of your solar agreement to make sure you are covered and following items (at minimum) must be considered:

  • Term of the warranty (years)
  • What is covered and what is not covered under the roof warranty?
  • Reliability of the solar company who issued the warranty
  • Response time in case if you need them to fix your roof

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4. Labor Warranty


Labor warranty is extremely important because it gives you the peace of mind that if your system needs repair due to a system malfunction, then your solar company must request equipment from the manufacturer (under equipment warranty) and send someone to replace the defective item at no charge to you for the period of the labor warranty. It is always good to get the longest possible labor warranty, but it is also important to keep in mind warranties are only as good as companies who offer them. This means if the company who is offering the warranty is no longer in business, then their warranty does not mean much unless it is backed by a third party. Some states require only 1 year labor warranty and some others require 10 years labor warranty, but your solar installer may offer you an extended labor warranty.

Please be aware that the labor warranty does not cover any intentional damages to the system. Usually, there is a service fee, repair fee and cost of equipment if your system is damaged due to reasons out of an installer’s and manufacturer’s control. Read your contract.

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5. Performance/Production Guarantee

The end result of installing a solar power system for your house is to generate solar electricity to offset your usage from the Utility Company. The amount of electricity (KWh) that your solar power system generates depends on a few variables such as:

  • Number of hours of usable sunlight per year per solar mounting plane and its azimuth
  • SQ FEET available for solar panels on your solar mounting plane(s)
  • Type of panels, inverter and their relative efficiency and dimension

In order to find out how many solar panels are needed for your house, first you must know how many KWh of electricity is used every year at your household. That information can be obtained from the Utility Company. Then, based on the KWh usage and the number of hours of usable sunlight on your mounting planes, you will find out how many panels are needed to offset 100% of your electricity usage with solar panels. But, there is another variable which is the SQFT of available roof space. Hence, you can come up with the optimized solar power system size based on actual numbers for the following variables:

  • Your actual annual KWh Electricity Usage
  • Your actual number of hours of usable sunlight per year per solar mounting plane
  • Your actual SQ FEET available for solar panels on your solar mounting plane(s)

As you may have concluded, there is a possibility that your roof space may not support 100% offset due to space limitation. But, a partial offset to lower your electricity rate is better that no offset!


When you meet with a solar installer, you must receive a performance estimation (KWh production) as well as a pricing estimation in writing. But, these estimations don’t mean anything until they are verified as a result of an actual site measurement done by the installer. Then, you must receive a report in the shape of a site layout that demonstrates the layout of the panels on your roof as well as the actual system production.

The system production is important because it determines your savings in case of a loan purchase, Lease or PPA and your ROI in case of a cash purchase.

There are some companies who offer Production/Performance Guarantee when you buy (cash and/or Loan) your solar power system, but there are some others who do not offer it. Please keep in mind that Guarantees and Warranties are as good as the companies behind them. This means, you should verify the financial stability of the Guarantor before paying anything extra for the performance guarantee.

The following items (at minimum) must be verified in the Production/Performance Guarantee before signing the solar agreement:

  • Annual KWh production per year for the duration of the guarantee based on the actual measurements and equipment manufacturers product specifications in terms of efficiency and annual degradation
  • Percentage of the guarantee relative to the annual KWh production based on actual measurements
  • The reimbursement rate in the case of under production


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