In photovoltaic offers, you will often come across an impressive claim: “warranty for many years.” But what does this promise cover? The panels, the inverter, the installation work, or the entire system’s production?
A photovoltaic system does not have one single warranty that covers everything. Each major component and service may come with different terms, time limits and support procedures.
At Solar Home, we want you to know what you are buying and what to look for in the documents you receive. The guide below will help you distinguish between the different types of coverage and properly organize your system documents.
Product warranty and performance warranty: Two different types of coverage
For photovoltaic panels, you need to distinguish between:
- The product warranty, which covers equipment defects, subject to the manufacturer’s terms.
- The performance or power warranty, which covers the retention of a specified power level over time, under defined testing conditions.
The two warranty periods are not necessarily the same. In the Trinasolar documentation for the Vertex S+ series, product and performance coverage are listed separately.
Ask for the relevant documents for the exact model number of your panels. A reference to a brand or a general product range is not enough to confirm the terms of your purchase.
What does the panels’ performance warranty really mean?
A performance warranty does not promise that your home will produce the same kilowatt-hours every year. It refers to the panels’ power, using a specific measurement methodology and accounting for the expected change over time.
Technical datasheets may include a graph showing the guaranteed power for each year, as in Trinasolar’s example for TSM-NE21.
Suppose, solely to help you understand the concept, that a panel with a rated power of 500 W has a contractual power retention threshold of 90% in a given year. The corresponding threshold would be 450 W under the specified testing conditions. This does not mean a guarantee of a specific annual output or savings.
Sunlight, shading, temperature, losses and the operation of the rest of the system all affect actual production. A lower reading in the app needs to be diagnosed before it can be linked to a warranty claim.
For the inverter, check the support process too
The inverter has its own commercial warranty. Ask when it begins, whether product registration is required and whether an extension is included in the offer or purchased separately.
It is equally important to know what happens when a fault occurs:
- Who opens and tracks the claim?
- Is repair or replacement provided for?
- What applies to transportation, removal and reinstallation?
- Are there additional costs for accessing the equipment?
- Which warranty remains in effect after replacement?
For example, SMA’s factory warranty terms distinguish between service levels and individual types of coverage. They also state that a replacement may carry over the remaining portion of the original period, rather than necessarily starting a new, full warranty.
To learn about how the component works, you can read our inverter guide.
For batteries, the number of years is not the only criterion
A battery may come with product coverage and separate terms for retaining its storage capacity.
Check whether performance coverage is linked to:
- The period from the start of the warranty.
- A minimum percentage of retained usable energy.
- The total energy delivered by the battery.
- The permitted operating conditions and system compatibility.
In the European terms for the BYD Battery-Box Premium HVS/HVM, limited performance coverage is linked to both time and a total energy output limit, depending on which is reached first.
Ask for an explanation of what the terms mean for your use. Do not automatically apply percentages and periods from another model, a different equipment generation or another country.
What does the installation work cover?
The manufacturer’s commercial warranty covers the equipment under its own terms. Responsibility and support for installation work need to be clarified separately in your agreement.
Ask for the covered work, the duration of the agreed coverage and the procedure for reporting problems to be stated in writing. For example, who will inspect an issue with the mounting, wiring or roof penetration points?
The same fault may initially look like a problem with different components. That is why you need a clear point of contact to coordinate the technical diagnosis and keep you informed about the next steps.
If you are comparing proposals, also make use of our guide to comparing two solar quotes.
A commercial warranty does not replace your statutory rights
For consumer purchases of goods from a business, the European Union distinguishes statutory protection for defective or non-conforming goods from an additional commercial warranty.
Commercial coverage cannot remove or limit your relevant statutory rights, as explained by the European Union’s Your Europe.
So, do not assume that the end of a specific commercial coverage period, by itself, resolves every question of liability. The application of rights depends on the specific purchase and contract; a business purchase is not automatically the same as a consumer purchase.
Which documents should you keep from day one?
Keep a shared folder, in print or digital form, with:
- The final proposal, contract and receipts.
- The exact equipment model codes and serial numbers.
- The warranty documents applicable to your purchase.
- Confirmation of warranty registration or extension.
- Commissioning deliverables and user instructions.
- Maintenance records, technical visits and correspondence.
Keep access to the monitoring data, too. In our guide to solar PV monitoring we explain how operating history helps you check your system.
The data help with investigations; by themselves, they do not prove that a claim is covered.
What should you do if a problem occurs?
Note when you first noticed the problem and what message appears in the app. Contact the installation company or designated support contact promptly and ask for a case number.
Before approving additional work, ask for information about the diagnosis, possible coverage and any charges. Keep correspondence and technical reports in your file.
Do not open devices or attempt repairs yourself. Follow the safety instructions and the procedure set out by the responsible technician.
Frequently asked questions
Does the long panel warranty cover the entire solar PV system?
No. Check whether it covers the product or the panels’ performance, and look separately for the terms applying to the inverter, battery and installation.
Does a performance warranty guarantee a specific reduction in your bill?
No. A panel’s power retention is not a guarantee of annual energy production, self-consumption or financial savings.
If the inverter is replaced, does the warranty period start over for everything?
Not necessarily. Ask for the terms that apply to the replacement and written confirmation of the remaining coverage.
Does the warranty cover damage caused by every external event?
Do not take this for granted. Check the exclusions and discuss insurance coverage for the system separately.
Choose clear terms and well-organized support
The value of a warranty lies in the combination of its duration, coverage and a clear service process. Ask for clarification before you buy and keep all documents after delivery.
At Solar Home, we can discuss the equipment and needs of your installation so that you have a clear understanding of the proposal. Contact us to plan your own system.
Sources and technical references
- European Union — statutory and commercial guarantees.
- Trinasolar — separate product and performance coverage and illustrative guaranteed power chart.
- SMA — Home factory warranty terms & Business.
- BYD — European warranty terms for Battery-Box Premium HVS/HVM.
The manufacturers are cited as examples of different terms. For each purchase, check the warranty version that applies to the specific product, date and country of installation.
