Buying and installing solar panels is one of the most momentous tasks of taking your home off-grid. When you finally take the plunge, it’s important to know how long they will last.
How long do solar panels last? Solar panels last for at least 25 years. Throughout their use, they slowly degrade which reduces their output over time. Most panels will continue to work for at least 80% efficiency for 25 years or longer. There are a few simple changes you can make to extend their life.
Why do solar panels degrade?
Solar panels degrade by about 0.5% every year. This varies depending on the manufacturer, the material, panel design, weather exposure, and other environmental factors.
The fastest degradation happens in the first two or three hours of sun exposure. When you first use new panels, the light, and heat from the sun cause minute changes to their chemical structure. Once this change has happened, the degradation rate slows down.
From then on, it is caused by several factors:
As the sun falls on your panels in the day and disappears at night, they heat up and cool down, causing them to expand and contract. This can cause tiny cracks to appear on the surface of the panels and reduce their efficiency.
Weather conditions that put strain or weight on the panels can cause them to warp or crack. Wind or heavy snow can bend and distort the shape of the frame and fittings, causing damage to its structure. Also, extreme heat and cold increases the size of the daily temperature changes and can make existing damage worse.
Humidity or rain
Once cracks and damage are present, the panels are more susceptible to degrade in damp or wet weather. Microcracks can allow water to seep in to prevent some parts of the panel from working efficiently.
Exposure to UV
This can cause the slow discoloration and break down of the back sheet. Most panels now come with UV shielding to prevent this from happening.
Poor quality panels
Solar panels made with cheaper materials are likely to bend more and degrade quicker. Buying budget products is likely to cost you more in the long run and result in you needing to replace them much sooner.
After about 30 years the rate of degradation is likely to increase. Once small cracks and damaged areas are present, the process can snowball as dirt and water get in through them. If you can prevent the daily small scale damage from happening throughout the lifespan of the panels, you stand a good chance of avoiding an acceleration in degradation.
Check out my recommendations for equipment that will help you take your home off-grid.
What can I do to extend the life of my solar panels?
To keep your panels working at their best for longer here are a few things you can do:
Buy quality panels from reputable companies
Avoid those made from thin films and look for those made from mono or polycrystalline. Look at customer reviews and talk to friends and neighbors with solar panels about their experiences with local companies.
Companies that offer excellent aftercare are worth their weight in gold. Look for those who will remain partnered with you throughout the life of the panels. This means that they will help you keep them maintained and in good condition.
Position them correctly
When preparing for installation, it is essential to choose the right location. You can put them on the ground, on purpose-built stands, on their house roof, garage roof, or shed roof. You must ensure that they are well away from trees or branches and are positioned to allow any water droplets to run off. They should also be securely fastened to prevent movement in the wind.
Most people choose to put panels on their rooves, this is a great place to have them, but it reduces your access should you need to inspect or clean them. If possible, position them so that you can get close to them.
It is essential to inspect the wiring and electronics regularly. If inverters or batteries aren’t working correctly, they can affect the rate of degradation. Many installers offer routine inspections once every five years; these are great ways to ensure everything is working as it should.
Repair any damage
If possible, regularly inspect your panels. If you find any damage, speak to the manufacturers about the best way to fix it.
You may not be able to repair it, but there may be steps you can take to prevent dirt or water from getting in. Clear polyurethane can be used to seal chips in the panel, or you can cover larger areas with tough transparent films.
Most dirt and dust that accumulates on solar panels can be removed with a hose or a spray and soft cloth or sponge. Do this in the morning or evening when the panels are cool.
Don’t walk on them
If you are cleaning your panels or crossing them to access another area on your roof, try to avoid stepping on them. They are built strong enough to take your weight, but you will run the risk of loosening the frame, driving dirt and dust into small cracks, or making existing damage wires.
When should I replace my solar panels?
If you treat your panels well and follow these steps, most modern designs could last for 40 years or more. The only reason you should need to replace them is if they suffer irreparable damage or if the degradation causes the output to fall below the level you require.
To know when this has happened, it is useful to keep a note of the output of your system. A few times a year, note down the production of the system. Try and do it on sunny days and record the temperature and weather in your notes.
If you have a 5kw system, you probably won’t see it hit the full amount, but you should see between 60 to 80%. Significant drops in power production may signal an acceleration in degradation. Once your system starts to deteriorate quickly or you find you struggle to charge your battery bank, it may be time for a replacement.
How long do solar inverters last?
Most off-grid inverters come with a 5 or 10 year warranty, but with careful treatment can last for up to 20 years. Keeping them cool, at least below 40C, and free from damp or dust will prevent any long-term damage that could age them faster.
It is also essential to regularly check and maintain your entire off-grid electricity set up. Rust, corrosion, or faulty components can all influence other elements in your circuit. If you can, it is useful to check the condition of your inverter a couple of times a year and check that the input and output displayed accurately reflects what your system actually produces.
Unless you are an expert or qualified, it’s a good idea to get a professional to carry out regular checks.
Related reading: Guide to off-grid solar inverters.
The lifespan of your solar panels depends on how you treat them. If you keep them clean, maintained, and free from damage, they could likely last for over 40 years. Getting them checked every few years and maintaining the components connected to them will all add to their life span and reduce the speed of degradation.
If your whole system is working well and effectively maintained, then it is likely that your panels will continue to work at a good level of efficiency for many decades.