Most solar panels will last for about 25 years or longer. This is the reason most of the Tier 1 manufacturers will provide twenty-five-year warranties, though most panels will last for more than that.
According to an NREL study done in 2012, eight in ten solar panels will function fine, well past the expiry of their warranty. However, past the warranty period, the efficiency of your solar panel will be significantly reduced though it will still be functioning. While the initial outlay may be hefty, the money you will save on your energy bills and the tax incentives will make the investment pay for itself in a few years.
Standard Solar Panel Warranties
Your typical solar panel warranty is about twenty-five years. Most manufacturers will guarantee that the panel will be operating at near peak efficiency for most of this period. Even in the last year of your warranty, you should expect at least 80% of the rated solar output from your panel. For instance, a 300 watt rated panel producing 80% of output should give you at least 240 watts in the last year of the 25 year warranty. You could get up to 85% efficiency or even a 30-year warranty with some companies, though most companies will offer 80% efficiency rates for a maximum of 25 years.
In addition to the efficiency warranty, you will also typically get a 10-year workmanship warranty. The warranty will cover manufacturing defects including things such as the frame, or faulty junction boxes. Some outliers will offer a twenty-year warranty, though the industry standard is 10 years.
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Solar Panel Degradation Rate
While solar panels can last for years, they do degrade over time. According to a 2012 study by the National Renewable Laboratory, solar outputs will fall by an average of 0.8 percent every year. For the most part, the degradation rate of the panel will depend on the panel brand.
Premium manufacturers typically provide better degradation rates that can be as low as 0.3 a year. Nonetheless, with better solar panel technology over the years, degradation is always falling with most companies now promising degradation rates at up to 0.5 percent a year.
Taking the numbers above your panel with 0.8% degradation should be down to 99.2 percent efficiency by the end of year 1 and 82.5% by the end of the 25th year. The better panel at 0.5% degradation per year should get you about 87.5% efficiency by the end of the 25th year of the warranty period.
You can thus use the performance and warranty to determine how much output to expect from your system over time.
Equipment Replacement and Maintenance?
While solar panels are expensive to install, once you have put up the initial outlay maintenance is relatively cheap. Many manufacturers advise that you spray your panels at least once a year. However, if you live in an area with regular rainfall, the rain should do much of the cleaning for you thus negating the need for annual cleaning. \
As for parts, solar panels tend to be quite robust and many parts will not need replacement over the life of the system. Most panels will cost no more than $200 to replace, though the manufacturer will typically include the panels in the warranty.
The inverter is one component that will need to be replaced at some point as it typically lasts for between 10 to 15 years. The inverter will set you back about $2000 though you can get it replaced for free since many manufacturers provide 10 to 12-year warranties on the inverter. If you are lucky you could get a manufacturer that has a twenty-five-year warranty on the inverter.
With twenty-five year warranties on efficiency and on parts, you can rest assured that your solar panel system will be reliable and need little maintenance long after you break even.
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Causes of Solar Panel Degradation
Panels tend to degrade in solar output due to a variety of issues the main one being the deterioration of electrical connections. In some cases, especially if you do not buy from a premium manufacturer, you may experience runaway degradation that results in rapid deterioration, ultimately resulting in complete failure.
The following are the main causes of solar panel deterioration:
1. Thermal Cycling – Due to changing seasons or even just the changes in temperature between night and day, the solar panel systems will expand and contract hundreds of times over its lifetime. Since the panels are made of different materials, they will be expanding and contracting at different rates, which puts a lot of strain on the joints and seals causing deterioration.
2. Dynamic Mechanical Load – Windstorms and even normal winds will cause panels to flex. While properly clamped down panels will flex much less, over time the flexing adds up.
3. Humidity – The combination of humidity and high heat that can be found in some areas of the US such as California can be hard on solar panels. If you bought a cheap panel, it could literally fall apart as it deteriorates physically and electrically.
4. UV damage – If you have a high-quality solar panel you do not have to worry about UV damage, as these will come with the best quality UV blockers. Conversely, low-quality panels will turn yellow and become inefficient really fast. Some may even come apart when the UV rays get to the glue holding them together.
5. Freezing – Water can be deadly to a solar panel especially if it enters the seals and joints of the panel in winter. When water enters the panel and freezes inside, it can cause expansion which will cause a deterioration of the panel.
How to Extend the Life of Your System
The panels themselves are going to be one of the more robust parts of the solar system. However, the other components such as the batteries and inverters will need frequent maintenance to keep them working at an optimum level.
1. Buy from Premium Manufacturers and install Correctly
The best way to make sure that your solar panel system lasts the longest is to buy from premium manufacturers. You should then inspect the system thoroughly and ensure that the wiring and panels are installed securely to prevent any electrical failure and physical damage.
2. Swap out your Inverters after Ten Years
Most inverters come with a ten-year warranty and if you have not upgraded to a 25-year warranty, you need to replace the inverter after ten years. It is always recommended to invest in an extended warranty for your inverter since you will certainly need to replace it after ten years. Moreover, replacing it will probably get you a newer and more efficient model that is ten years ahead of your old one.
3. Maintain and Replace the Batteries
If you have an off-grid system you will need to regularly inspect and maintain your batteries several times every year. The best batteries come with a warranty of up to ten years though they will still fail if you do not take care of them. To ensure that your lead batteries last the longest, always recharge them fully before using them. You will also need to recharge them constantly to prevent permanent damage, as leaving them without a charge for an extended period is not good for them. If you maintain your batteries properly and account for proper inverter output, solar power, and battery capacity, they should last for between 5 to 15 years.
4. Account for Efficiency Loss
Your solar panels will typically last for twenty-five years, and hence you are unlikely to be replacing the panels until the warranty is up. However, you can always keep the efficiency of the solar panel system up by adding capacity. Since you can always find new parts from the secondary market, you could replace the old inefficient parts and get your system working just as if it was new.
5. Schedule Regular Inspections
Have either a service provider or the installer come to your home on a regular schedule to examine your solar system and provide any maintenance service required. With proper inspection, you can get to potential issues such as exposed wires, inverters, loose racking, and any other issues before they become critical.
6. Clean Debris from the Panels
By keeping your solar panels clear of debris such as tree branches, bird droppings, rocks, and soil, they will last longer. Good care can even take them further than the twenty five year warranty provided by the manufacturer. If you can, ask your installer or service provider to recommend specialty products such as solar panel critter guards, which will prevent birds and squirrels from nesting under the panels and damaging them.
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