It is important to understand exactly what you will be getting from your solar energy system over the long-term. Solar panels are one of the most costly sides of this system investment. Knowing how long you can expect your pv modules to last is critical in calculating ROI and monthly savings on your electric bill.

Installers and DIY system owners want to know "how long will solar panels last?" There are of course, several variables when it comes to getting a good idea how long your solar panels will last while still processing solar energy efficiently.

One thing you need to know is  solar panels slowly degrade in efficiency over time. It is not much but, it will add up over time (hence most solar panel warranties may only cover a guaranteed 80% out out after 20-25 years). Count on a efficiency derate of 0.25% to 1% per year. You can safely assume your solar panels will be producing raw DC solar power of anywhere from 75-90% by 25-30 years of usage.

We do notice certain solar panel  manufacturers do perform better and retain higher levels of efficiency over time. Brands like SolarWorld, Canadian Solar, Panasonic and LG Solar appear to maintain long term performance over their less costly counterparts. These PV modules have been known to last 30 years or longer while still holding onto 80%+ efficiency - this makes a big difference in the final return for your system, and how long after you may need to replace your solar power system components.

Average Solar Panel Warranty

Commonly, you will see solar panels with a limited product warranty of 10 years. This covers mechanical integrity and stability of the solar panels, and assumes the panels were installed properly and no indications of localized impacts or external forces, (any damages caused by abrasion, improper installation or animals are exempt from this part of the warranty).

The main bulk of the warranty people most often hear of is the average 25 year limited performance warranty. It is this warranty that usually matters most, with the manufacturer covering a slow and steady annual power decline of no more than 0.5-1%, with a final degradation factor of no more than a total amount such as 83% in Canadian Solar's case. The limited performance warranty is determined for verification using Standard Testing Conditions. The actual power output measurement is either carried out by the manufacturer or by a recognized 3rd party testing institute.

Here are a few of the common solar panel warranties from leading solar panel manufacturers: Canadian Solar, LG Solar, Panasonic, and SolarWorld.

All of this translates fairly simply into what you can expect from your solar panels wattage output over time - i.e., a 320 watt module should produce 256 watts over the 25 year period for a 80% limited performance warranty. 

*Read about Solar Panel Ratings here

What Happens After My Warranty Period Ends?

When your solar panel limited performance warranty ends, your solar panels will continue to produce energy all the same. However, count on a continued degradation of the modules efficiency. Your modules will still be performing as they always had. Solar panels commonly produce energy at a decent efficiency rate for many years after the end of the performance warranty.

Coincidentally, the National Renewable Energy Laboratory (NREL) conducted a study on  Photovoltaic Degradation Rates. They found almost 80% of solar panels last longer than their manufacturers warranty, and the average degradation rate for solar panels built prior to 2012 is between 0.5% to 0.8% per year. New PV modules will have even better rates of degradation as silicon solar power is refined and updated.

How Can I make My Solar Panels Last Longer?

While  solar panels are built to last with increasing warranty periods from quality manufacturers, there are steps system owners can take to ensure solar panels will last longer, maintain efficiency, and provide better overall performance for the life of your system.

Cleaning off solar panels of snow, leaves and debris during cooler times in the day (to avoid thermal stress), and using water with low mineral content and near neutral pH levels is important. This will maximize light exposure and lower degradation rates. Furthermore, a properly designed system will outperform when paired with the most compatible inverter systems, and taking into consideration the average warranty of inverters - you may need to replace those long before your solar panels begin to burnout. 

*Read About How to Clean Your Solar Panels here

How Does This Affect My Systems ROI?

Solar panels that outlast their warranties will deliver additional return on investment due to the extended period of power generation past the expected life expectancy. While the warranty on modules does simply cover that time period, there is clearly no guarantee that the PV modules will outlive their manufacturers due date. It is safe to assume though, that modules will continue to perform well after this period is over. Solar panels do not have moving parts, and therefore are usually more reliable.

How Can I Extend The Life of My Solar Energy System?

The real question may be "How long will my solar power system last?" Indeed, Solar panels and racking and mounting will be the most reliable parts of your system. As clearly the modules are built to last, and the racking and mounting system is created with (usually) non-moving components form durable metals made to withstand elements and time, the only other issues that pose a problem are the inverter(s), monitoring equipment, balance of systems items, and batteries. 

*Learn how to go solar with our Solar Guide

Inverters generally are created with a shorter life expectancy than solar panels. As such, they may need to be replaced long before the solar panels begin to lose their ability to efficiently generate power. Inverters have varying life spans, while generally they are known to carry 10-15 year warranty periods, some newer models may be capable of going much longer with updated warranties. Enphase IQ microinverters have a 25 year warranty, effectively matching the standard solar panel warranty - this does drive extra value for the slightly higher cost of choosing to go with microinverters rather than a standard central or string inverter. SolarEdge carries an average 12 year warranty on their inverters, although they do present a 25 year warranty on power optimizers.

Here are a few of the common inverter warranties (and other components related to inverter systems) from leading inverter manufacturers: Enphase Energy, Fronius, SMA, and SolarEdge.

If you purchase a system for off-grid or a hybrid PV array with  battery back-up, then taking into account the time-frame of the battery bank storing energy effectively will be a priority in keeping your system active and running well into the future. Usually batteries will store and redistribute power on demand from anywhere between 5-10 years. Newer battery technologies such as lithium-ion will provide warranties around 10 years with a guaranteed 80% or higher efficiency rating. While older more traditional AGM, Flooded, and GEL battery warranties may be 10 years or shorter, but they will cover the whole batteries capacity rather than a scaling percentage over time. 

Here are common battery warranties from our most popular renewable energy battery banks: Concorde Battery, Enphase Energy, LG Chem, and Trojan Battery.

Build An Affordable and Quality Solar Power System

First thing you need to remember is your solar panels will most likely outlast the other components of your system (besides the  racking and mounting) by a long shot. If your system does begin to lose power in the long term, and can no longer account for your total energy usage, then you will have to replace or expand your system. The best way to get the most value and purpose from your solar power system is to research the best solar panel, inverter, battery, and racking and mounting manufacturers to design a system that will work hard for your goals well into the future. We can help design and supply a quality system for DIY projects and installers looking to get the most value from investing in solar.