The service life of equipment is one of the main factors to consider before making an investment decision, and this also applies for power generation systems. Solar panels are durable devices with simple maintenance needs, and there are now many brands that offer 25-year product warranties. This means you can get a source of clean electricity for more than two decades, which can help you save thousands of dollars in power bills over time.
source: Alternative Power Solutions Inc.
Solar panels can often achieve a payback period of less than five years in places with expensive electricity and/or abundant sunshine. Incentive programs from local governments and utility companies can also help improve their return on investment.
Even with less favorable conditions, the payback period of home solar systems is generally less than 10 years.
- Having a 25-year service life covered by a warranty, solar panels are one of the safest investments available for homeowners.
- Their typical payback period is much shorter than their service life, and their electricity is essentially free after your investment is recovered.
Like any other piece of equipment, solar panels only reach their rated service life when they are used as intended by the manufacturer. Photovoltaic modules must be attached firmly to your roof structure with a suitable racking system, and they must be wired properly to prevent electrical faults.
Many brands now offer 25-year product warranties, but these only apply for solar panels that are used properly. If they are damaged as the result of an incorrect installation, the warranty will be normally voided.
It’s important to note that a functional solar power system includes many components beyond the photovoltaic panels themselves. For example, you need an inverter to convert the DC power generated by solar panels into the AC power needed by home devices.
If you want a home solar system with energy storage capacity, you also need to add batteries. Like any electrical installation, a solar PV system also includes wiring and circuit breakers, and you need a durable racking system that will hold the panels in place throughout their service life.
Solar Panels: A 25-Year Asset That Generates Clean Power
Solar panels are tough and durable devices: there are satellites in orbit that have been using the same PV cells for decades. Unlike most other generation systems, solar panels have no moving parts, and this means they aren’t exposed to mechanical wear.
However, even the best solar cells lose their generation capacity over time, and most manufacturers offer a 25-year power production warranty for this reason.
Some brands are now offering solar panels with a 30-year power production warranty, but a minimum of 25 years is considered an unofficial “standard” in the industry.
When companies install solar arrays for their buildings, they generally assume a 25-year or 30-year asset life. Solar panels can last longer, but this is the period of guaranteed electricity production covered by a manufacturer warranty.
Utility-scale solar developers also assume 25–30-year periods in their cash flow projections since it gives them an idea of the revenue available over time. This is very useful when negotiating with banks and investors who are interested in financing their solar power projects.
Having a 25-year power production warranty is great when you purchase solar panels, but you also need to consider their degradation rate. All solar panels lose their generation capacity over time, but not at the same rate.
- For example, you may find two solar panels of the same wattage, but one loses 0.80% output per year while the other only loses 0.25% output per year.
- Although the rated wattage is the same, the electricity output of the second panel is much higher over time since its degradation rate is much lower.
All solar panels suffer their highest degradation during the first year of use, where they typically lose between 2% and 3% of their rated capacity. From year 2 onward, the degradation rate of most modules is less than 1% annually, and the best products have a degradation rate as low as 0.25%.
The following table shows how different degradation rates impact the productivity of solar panels over time, assuming a 2% loss during the first year.
|Solar Panel Degradation||0.25%/year||0.40%/year||0.50%/year||0.70%/year|
|Remaining Capacity, Year 1||98.00%||98.00%||98.00%||98.00%|
|Remaining Capacity, Year 5||97.00%||96.40%||96.00%||95.20%|
|Remaining Capacity, Year 10||95.75%||94.40%||93.50%||91.70%|
|Remaining Capacity, Year 15||94.50%||92.40%||91.00%||88.20%|
|Remaining Capacity, Year 20||93.25%||90.40%||88.50%||84.70%|
|Remaining Capacity, Year 25||92.00%||88.40%||86.00%||81.20%|
In this example, note how the solar panels with a degradation of 0.25% per year still generate 92% of their rated output after 25 years. On the other hand, the solar panels degrading at 0.70% per year only have 81.20% of their output left.
To visualize the impact of degradation rates, assume you purchase a home solar system with a design output of 10,000 kWh per year:
- Using solar panels with a slow degradation rate (0.25% per year), this PV system can still generate 9,200 kWh after 25 years of use.
- Using solar panels with a faster degradation rate (0.70% per year), the system can only generate 8,120 kWh after 25 years of use.
As you can see, several factors come into play when analyzing the rated service life of different solar panels. The rated wattage and warranty coverage period are important, but you also need to consider electricity production over time, which depends on the degradation rate.
How Long Do Solar Shingles and Solar Tiles Last?
Unlike solar panels, which are installed above your roof with a racking system, solar shingles and tiles become a part of the roof. These products can be a great option for new homes, since you combine your roof and solar array into a single system, reducing the total combined installation costs.
These products are also recommended if you have an old roof that needs a replacement soon: instead of installing a new roof with solar panels, you can use BiPV shingles or tiles with built-in solar cells.
Since solar shingles and tiles use the same technology as traditional solar panels, their performance over time is similar. This means you can also expect a 25–30-year power production warranty when installing a solar roof.
The same recommendation given in the previous section applies here: look for solar roof systems with a slow degradation rate, since they will generate more electricity over time.
Solar Panel Product Warranty and Power Output Warranty: What Is the Difference?
When checking solar panel specifications, you will notice that manufacturers actually offer two separate warranties: the product warranty and the power output warranty. Understanding the difference between them is very important.
- The power output warranty replaces your solar panels if their electricity output decreases faster than the specified degradation rate.
- On the other hand, the product warranty replaces your solar panels if they fail due to manufacturing defects and workmanship.
As mentioned before, the typical power warranty is 25-30 years when purchasing high-quality solar panels. On the other hand, product warranties are more variable, ranging from 10 to 25 years. Keep in mind that each warranty has its own coverage period: you may find solar panels that come with a 25-year power warranty, but only a 10-year product warranty.
The same solar panel model may have different product warranty periods, depending on who installs your residential PV system.
For example, a brand may offer a 25-year product warranty if you hire one of their approved installers, but only a 15-year warranty if you work with other companies.
Generally, the savings achieved by solar panels are analyzed for a 25–30-year service life, even if the product warranty is shorter.
EnergySage gathers useful data about the solar power industry, and they have a list of manufacturers with 25-year product warranties: LG Solar, Panasonic, Silfab, Solaria, SunPower, Q CELLS, REC, Mission Solar, LA Solar Group, and Winaico.
How Long Do Solar Inverters and Home Batteries Last?
High quality solar panels can be expected to last for 25 years or more, but other PV system components have shorter service lives. Solar inverters have a typical service life of 10 years. This means your solar panels will still have 15 years of guaranteed power output when your first inverter reaches the end of its service life.
If you’re considering a solar power system with energy storage, home batteries also have a typical service life of 10 years.
Batteries are optional, unlike inverters, which means your solar panels can continue operating when batteries reach the end of their service life. However, you need to purchase a new unit if you plan to continue using energy storage when the first battery expires.
Wiring, circuit breakers and racking components can normally last as long as your solar panels. However, this is only true when you purchase high-quality components and get a professional installation.
Finally, you need to consider the remaining service life of your current roof. The last thing you would want is having to replace your roof after installing solar panels.
Removing and reinstalling a solar panel system is a complex procedure, and in many cases, you will void warranties.
Ideally, solar panels should be installed on roofs that will not need a replacement during the next 25-30 years.
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