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Do solar panels lose efficiency over time? Should you replace it at the end. Solar module efficiency

Do solar panels lose efficiency over time? Should you replace it at the end. Solar module efficiency

    Do solar panels lose efficiency over time? Should you replace it at the end?

    Yes, solar panels lose efficiency over time. The loss in solar panel efficiency over time is called degradation and it is a natural consequence of exposure of the solar panel to ultraviolet rays and adverse weather conditions. The National Renewable Energy Laboratory estimates this degradation to be between 0.5% to 0.8% per year. In other words, the solar panels annual production drops by 0.5% to 0.8% per year.

    What is solar panel efficiency?

    Efficiency in solar panels is defined as the energy output from a given surface area of the solar panel. The higher the energy output from a given surface area, the higher the efficiency. Similarly, lower the energy output from a given surface area, the lower the efficiency. As solar panels get more and more efficient over time, manufacturers can increase not only the efficiency of the solar panel but also the rated power capacity of the solar panel. The below graph shows the power increase of solar modules over the last decade. At the start of the decade the maximum rated power of a solar panel was 295 Wp and towards the end of the decade this value almost doubled to 600 Wp.

    Why does solar panel efficiency drop?

    Light induced degradation occurs when the solar panel is first exposed to solar irradiation and the efficiency of the solar panel is reduced by 1 to 3% on average ( This loss in efficiency cannot be avoided and happens once during the life of the solar panel.

    Potential induced degradation is caused by voltage, heat and humidity. However, the PID effect does not occur on all solar modules. PID occurs when the module voltage potential and leakage current drive ion mobility within the module between the semiconductor material and other elements of the module (example glass and frame), thus causing the modules power output capacity to degrade. This potential loss in efficiency can be avoided by using Tier 1 solar panels from quality suppliers. The solar panels from quality suppliers will have solid encapsulation and diffusion barriers that offer better long-term protection against PID loss.

    Solar panels have a design life between 25 to 30 years, during this period the solar panels are exposed to heat and cold along with rain, snow, hailstorms, etc. The natural wear and tear of the solar panels causes the solar panel efficiency to drop.

    What other factors can affect solar panel efficiency?

    Apart from the three factors mentioned in the previous section there are other factors that directly and indirectly affect the efficiency of the solar panels and the solar plant.

    These factors are discussed below.

    Solar panel orientation

    The angle of the solar panel and the amount of light hitting it are both important factors that can either reduce or increase the efficiency. For example, if the project is located in the south of the equator, solar panels facing north produce maximum power and energy. Similarly for projects located in the north of the equator, solar panels facing south produce maximum power and energy.

    solar, panels, lose, efficiency

    Pitch of the roof

    The slope of the roof will impact how much sunlight is hitting the solar panels throughout the day and has a direct impact on solar production.


    Higher temperatures can reduce output and lower the efficiency of the solar panels.


    A small shade on a solar panel can greatly reduce the solar panel’s output. In most of the residential solar projects, 15 to 18 solar panels are connected in series to form a string. If any one of the solar panels in the string has a shadow on it, it can lead to massive loss in production and reduce the overall efficiency of the solar plant.


    Design of the solar plant plays a key role in total plant performance and solar panel efficiency. Solar plant design is the process of designing a solar plant considering the total plant capacity and breaking this information down to string design, number of inverters, protection devices, panel position and orientation. A good design ensures using the right size of cables and inverter. If cables and inverters are undersized it will lead to a drop in solar panel efficiency and if they are oversized, it could financially impact the project.

    Balance of system

    Balance of system are the components used in the solar plant apart from the solar panels. This includes mounting structure, cables, inverters, and protection devices. Its key is to size and use quality products for the balance of the system. It is highly recommended to use good quality suppliers for all components used in the solar plant, especially since the life of the solar plant is estimated between 25 to 30 years.

    The factors mentioned above must be assessed during the design and installation of the project. By using qualified and certified installers, the efficiency losses within a solar plant can be drastically reduced.

    What are the standard warranty and guarantees offered by manufacturers?

    Solar panel manufacturers generally provide two types of warranties. The first is a product warranty and the second is a power warranty. The product warranty covers the anodized aluminum frame, the glass protecting the top of the panel, the IP67 rated junction box, the solar cells and connectors. The product warranty is very similar to the standard warranty you get when you buy a new product. Linear power warranty on the other hand takes into account the degradation of the solar panel over time. Most manufacturers provide a warranty on the power output of the solar panel.

    The warranty period provided for product warranty and linear power warranty is decided by the manufacturer. Most Tier 1 module suppliers like Jinko Solar, Trina and JA solar provide 12-year product warranty and 25-year linear power warranty on the solar panels

    How much solar production do I lose due to solar panel degradation?

    Jinko solar module JKM545 has a module efficiency of 21.13% at standard test conditions. The manufacturer provides a 25-year linear power performance warranty at 0.55% annual degradation. This means after 5 years of operations the solar panel is expected to output 95% of its rated power and after 10 years of operations output 92% of its rated power.

    In 5 years of operations, there is 5% drop in production and in 10 years of operations, there is 8% drop in production. The production drop is linear across the life of the solar panel, this can be observed from the figure above.

    Do I need to replace my solar panels due to degradation with higher efficiency and higher power panels?

    The solar power that can be packed into a panel has almost doubled in the last decade, also the efficiency of solar panels has increased by over 5% in the last couple of years. It can be noted that in the next few years, the power capacity and efficiency of solar panels will further increase. Replacing old solar panels with new solar panels is called repowering. This is common in large solar projects.

    Given that in most cases a solar installation has a pay back in less than 5 years, it is not advisable to replace the modules, especially since most solar panel manufacturers provide a 25 year performance warranty.

    solar, panels, lose, efficiency

    What must you consider while installing solar panels on your roof?

    Efficiency of solar panels are affected by multiple factors, some of them can be controlled and others can’t. While deciding on installing solar power on your roof, you must consider buying solar panels from Tier 1 suppliers. Solar panel suppliers are ranked into Tier 1, Tier 2, and Tier 3. Tier 1 solar panels are panels that are manufactured by big brands who have a good reputation in the industry. It is a lot safer to build a solar plant using Tier 1 suppliers than Tier 2 and Tier 3. This doesn’t mean Tier 2 and Tier 3 are bad, but Tier 1 solar panels are a good marker for trust and reputation. Using tier 1 suppliers one can reduce efficiency losses within a solar plant.

    The other efficiency losses come during the design and installation phase of the solar plant. This loss can be minimized by using certified solar plant installers.


    It is important to note one cannot eliminate efficiency losses but can minimize it by using quality solar panels and balance of system, sizing the solar plant correctly and using certified installers to install the project.

    Sunny superpower: solar cells close in on 50% efficiency

    For solar cells, efficiency really matters. This crucial metric determines how much energy can be harvested from rooftops and solar farms, with commercial solar panels made of silicon typically achieving an efficiency of 20%. For satellites, meanwhile, the efficiency defines the size and weight of the solar panels needed to power the spacecraft, which directly affects manufacturing and launch costs.

    To make a really efficient device, it is tempting to pick a material that absorbs all the Sun’s radiation – from the high-energy rays in the ultraviolet, through to the visible, and out to the really long wavelengths in the infrared. That approach might lead you to build a cell out of a material like mercury telluride, which converts nearly all of the Sun’s incoming photons into current-generating electrons. But there is an enormous price to pay: each photon absorbed by this material only produces a tiny amount of energy, which means that the power generated by the device would be pitiful.

    Hitting the sweet spot

    A better tactic is to pick a semiconductor with an absorption profile that optimizes the trade-off between the energy generated by each captured photon and the fraction of sunlight absorbed by the cell. A material at this sweet spot is gallium arsenide (GaAs). Also used in smartphones to amplify radio-frequency signals and create laser-light for facial recognition, GaAs has long been one of the go-to materials for engineering high-efficiency solar cells. These cells are not perfect, however – even after minimizing material defects that degrade performance, the best solar cells made from GaAs still struggle to reach efficiencies beyond 25%.

    Further gains come from stacking different semiconductors on top of one another, and carefully selecting a combination that efficiently harvests the Sun’s output. This well-trodden path has seen solar-cell efficiencies climb over several decades, along with the number of light-absorbing layers. Both hit a new high last year when a team from the National Renewable Energy Laboratory (NREL) in Golden, Colorado, unveiled a device with a record-breaking efficiency of 47.1% – tantalizingly close to the 50% milestone (Nature Energy 5 326). Until then, bragging rights had been held by structures with four absorbing layers, but the US researchers found that six is a “natural sweet spot”, according to team leader John Geisz.

    Getting this far has not been easy, because it is far from trivial to create layered structures from different materials. High-efficiency solar cells are formed by epitaxy, a process in which material is grown on a crystalline substrate, one atomic layer at a time. Such epitaxial growth can produce the high-quality crystal structures needed for an efficient solar cell, but only if the atomic spacing of each material within the stack is very similar. This condition, known as lattice matching, restricts the palette of suitable materials: silicon cannot be used, for example, because it is not blessed with a family of alloys with similar atomic spacing.

    Devices with multiple materials – referred to as multi-junction cells – have traditionally been based on GaAs, the record-breaking material for a single-junction device. A common architecture is a triple-junction cell comprising three compound semiconductors: a low-energy indium gallium arsen­ide (InGaAs) sub-cell, a medium-energy sub-cell of GaAs and a high-energy sub-cell of indium gallium phosphide (InGaP). In these multi-junction cells, current flows perpendicularly through all the absorbing layers, which are joined in series. With this electrical configuration, the thickness of every sub-cell must be chosen so that all generate exactly the same current – otherwise any excess flow of electrons would be wasted, reducing the overall efficiency.

    Bending the rules

    Key to the success of NREL’s device are three InGaAs sub-cells that excel at absorbing light in the infrared, which contains a significant proportion of the Sun’s radiation. Achieving strong absorption at these long wavelengths requires InGaAs compositions with a significantly different atomic spacing to that of the substrate. Additionally, their device has been designed with intermediate transparent layers made from InGaP or AlGaInAs to keep material imperfections in check. Grading the composition of these buffer layers enables a steady increase in lattice constant, thereby providing a strong foundation for local lattice-matched growth of sub-cells that are not riddled with strain-induced defects.

    The NREL team, which has pioneered this approach, advocates the so-called “inverted variant” structure. With this architecture, the highest energy cell is grown first, followed by those of decreasing energy, so that the cells lattice-matched to the substrate precede the growth of graded layers. This approach improves the quality of the device, while the fabrication process also results in the removal of the substrate – a step that could trim costs by enabling the substrate to be reused.

    One other technique that can further boost solar-cell efficiency is to FOCUS sunlight on the cells, either with mirrors or lenses. The intensity of light on a solar cell is usually measured in “suns”, where one sun is roughly equivalent to 1 kW/m 2. Concentrated sunlight increases the ratio of the current produced when the device is illuminated compared to when it is in the dark, thereby boosting the output voltage and increasing the efficiency. The gain is considerable: the NREL device achieves a maximum efficiency of just 39.2% when tweaked to optimize efficiency without any concentration, a long way short of the 47.1% record.

    When Geisz and colleagues assessed how the performance of their six-junction cell varies with concentration, they found that peak efficiency occurs at 143 suns. Nevertheless, the device still produces a very impressive 44.9% efficiency at 1116 suns, which would generate a large amount of power from a very small device. As a comparison, a record-breaking cell operating at 500 suns could deliver the same power as a commercial solar panel from just one-thousandth of the chip area. At such high concentrations, however, steps must be taken to prevent the cell from overheating and diminishing performance.

    Just over a decade ago, this approach to generating power from high-efficiency cells spawned a ­concentrating photovoltaic (CPV) industry, with a clutch of start-up firms producing systems that tracked the position of the Sun to maximize the energy that could be harvested from focusing sunlight on triple-junction cells. Unfortunately, this fledgling industry came up against the unforeseeable double whammy of a global financial crisis and a flooding of the market with incredibly cheap silicon panels produced by Chinese suppliers. The result was that so few CPV systems were deployed that even on a sunny day when all operate at their peak, their global output totals less than one-tenth of the power of a typical UK nuclear power station.

    Extra-terrestrial encounters

    Far greater commercial success for makers of multi-junction cells has come from powering satellites, most recently buoyed by the rollout of satellite broadband by companies such as OneWeb and Starlink. The key advantage here is that high-efficiency cells can drive down the costs of making and launching each satellite. As well as reducing the number of cells needed to power the spacecraft, higher efficiencies shrink both the size and weight of the solar panels that form the “wings” of the satellite. While launch costs have plummeted over the last few decades, satellite operators can still expect to pay almost 3000 per kilogram to get their spacecraft into orbit – and thousands of satellites are due to be deployed over the next few years.

    For a solar cell in space, the crucial metric is the value at the end of its lifetime – after the device has been bombarded by radiation

    However, for a solar cell in space, the crucial metric is not the initial efficiency but the value at the end of its intended lifetime after the device has been bombarded by radiation. Compound semiconductors hold up to this battering far better than those made from silicon. Early studies showed that the difference in efficiency of compound semiconductors rises with age from 25% to 40–60%, which ensured the dominance of triple-junction cells for space applications. Even so, the efficiencies of the best commercial cells for satellites remain limited to around 30–33%. This is partly because the solar spectrum beyond our atmosphere has a stronger contribution in the ultraviolet, where it is much harder to make an efficient cell, and partly because there are no concentrating optics to FOCUS sunlight onto the cell.

    To drive down the watts-per-kilogram of solar power in space, a US team working on a project known as MOSAIC (micro-scale optimized solar-cell arrays with integrated concentration) has been making a compelling case for CPV in space. The team points out that it should be relatively easy to orientate the solar panels on a satellite to maximize power generation with lenses in front of the cells shielding them from radiation. Concentrations must be limited to no more than around 100 suns, however, because cells in space cannot be cooled by convection, only by heat dissipation through radiation and conduction.

    For CPV to have a chance of succeeding in space, the large and heavy solar modules used in early terrestrial systems must be replaced with a significantly slimmed-down successor. Technology pioneered by project partner Semprius, a now defunct CPV system maker, excels in this regard. The firm developed a process that uses a rubber stamp to parallel-print vast arrays of tiny cells, each one subsequently capped by a small lens.

    The best results have come from stacking a dual-junction GaAs-based cell on top of an InP-based triple-junction cell separated by a very thin dielectric polymer. Current cannot pass through this polymer film, so separate electrical connections are made to extract the current from each cell independently. While this doubles the number of electrical connections, it eliminates the need for current matching between the two devices. Lifting this restriction gives greater freedom to the design, potentially enabling this approach to challenge the efficiency of NREL’s record-breaking device under high concentrations. Operating at 92 suns under illumination which mimics that in space, the team’s latest device, still to be fully optimized, has an efficiency of 35.5%.

    Towards 50%

    The NREL researchers know what they need to do to break the 50% barrier. The goal they are chasing is to cut the resistance in their device by a factor of 10 to a value similar to that found in their three- and four-junction cousins. They are also well aware of the need to bring down the cost of producing such complex multi-junction cells.

    Also chasing the 50% efficiency milestone is a team led by Mircea Guina from Tampere University of Technology in Finland. Guina and colleagues are pursuing lattice-matched designs with up to eight junctions, including as many as four from an exotic material system known as dilute nitrides – a combination of the traditional mix of indium, gallium, arsenic and antimonide, plus a few per cent of nitrogen.

    Dilute nitrides are notoriously difficult to grow. Back in the 1990s, German electronics powerhouse Infineon developed lasers based on this material, but they were never a commercial success. recently, Stanford University spin-off Solar Junction showcased the potential of this material in solar cells. Although the start-up went to the wall when CPV flopped, devices produced by the company grabbed the record for solar efficiency in 2011 and raised it again in 2012 with triple-junction designs. Guina and co-workers are well positioned to take their technology further. They have made progress in producing all four of the dilute nitride sub-cells needed to produce record-breaking devices, and their efforts are now focused on optimizing the high-energy junction. The team’s work has been delayed due to the COVID-19 pandemic, but Guina believes that the approach could break the 50% barrier, possibly raising the bar as high as 54%.

    There is still a question of impetus, however. The lack of commercial interest in terrestrial CPV may well encourage Guina to change direction and FOCUS on chasing the record for space cells with no concentration. Much of today’s multi-junction solar-cell research is not focusing on power generation here on Earth, so while that 50% milestone is tantalizingly close, it might not be broken anytime soon.

    Richard Stevenson is editor of Compound Semiconductor magazine, e-mail

    Solar Panel Efficiency Over Time (Plus Tips to Improve It)

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    Find the best price from solar installers in your area.

    You’ll likely read about solar panel or solar cell efficiency in just about every article about panel performance, but many homeowners and solar customers still don’t understand why it’s such a crucial metric in the industry. Ultimately, your panel efficiency rating and degradation over time determine your energy output and, consequently, how much money you save on your utility bills.

    In this article, we’ll be discussing why and how panels degrade over time, how long panels typically last, when you should replace them and how to boost performance and production until you do.

    Do Solar Panels Lose Efficiency Over Time?

    Yes, all solar panels lose efficiency over time, and the rate at which they do depends on a variety of factors, including the panel brand.

    Solar panel degradation happens because of constant exposure to UV light, cyclic changes in panel temperature and more, all of which reduce the panel’s ability to absorb sunlight and convert it to usable electricity for your home. We’ll explain the reasons for degradation in greater detail in a later section.

    For now, it’s useful to understand just how much efficiency you can expect your solar panel system to lose over time.

    The actual rate of degradation depends on the brand of the panel you install, but the average is around 0.5% per year. The only exception is the first year after installation, which is the only time degradation is accelerated. The typical panel loses around 2.5% of its starting efficiency in the first 12 months.

    Since most panels come with a 25-year performance warranty, it’s convenient to use that time frame to gauge degradation. With a 2.5% dip in the first year and a 0.5% dip per year over the following 24 years, that leaves you with a total loss of 14.5% and around 85.5% of the starting efficiency at the end of the 25 years.

    Since the average panel efficiency starts at around 18.5%, the 14.5% loss would leave you with a total panel efficiency of 15.39% at the end of the 25-year efficiency warranty.

    Blue Raven Solar

    How Has Solar Panel Efficiency Improved Over the Years?

    The first solar cell was invented back in 1883 and had an efficiency of below 1%. It wasn’t until about 70 years later that a PV cell with practical application—due to an efficiency rating of around 6%—was invented.

    Since the 1950s, there have been a handful of advancements that have helped push panel efficiency higher and higher toward the 22.8% residential panels—under standard test conditions— from SunPower are now capable of. We’ll explain the difference these advancements made briefly below.

    • Late 1950s — Monocrystalline solar cells: Monocrystalline solar cells are made from a single sheet of silicon as the semiconductor rather than multiple silicon crystals, as is the case with polycrystalline solar cells. This advancement brought the possible efficiency up from 1% to around 6%, making solar a viable option for energy production.
    • 1983 — Solar tracking technology: Panels generate more power when they receive more direct sunlight. In the early 80s, the first sun-tracking mounting system was invented. This didn’t increase cell performance, but it allowed for increased production throughout the day.
    • Mid-1980s — Anti-reflective coatings: Anti-reflective coatings help prevent energy from the sun from bouncing off of the rear wall of the solar panel and getting lost to the environment. These coatings were developed in the 1980s, and there have been many iterations and improvements since.
    • 1988 — Multi-junction solar cells: Multi-junction cells, also known as tandem cells or tandem perovskite cells, are manufactured using several light-absorbing materials to capture a wider range of solar energy. In the 80s, these peaked efficiency at around 40%. However, given how expensive it was to produce them, the tech was only used for specific applications, like energy production in space.
    • 1989 — PERC technology: The first passivated emitter and rear contact (PERC) solar cell was invented. This technology improved efficiency by upwards of 10%, as it allowed for the reabsorption of solar energy that normally would have been lost.
    • 2010 — Bifacial panels: Bifacial panels essentially trap solar energy between two surfaces until it can be absorbed by the solar cells inside. This technology was invented in the 70s but wasn’t popularized until around 2010 due to production limitations and cost.
    • Early 2020s — Tandem solar cells for commercial production: The multi-junction or tandem solar cells developed in the late 80s started to become viable for use in residential solar systems. They boosted potential efficiency by an additional 25% and could allow for home solar systems to reach efficiencies of around 30%.

    Over the years, improvements to the adhesives used for cell connection have also played a role in improving panel efficiency and durability.

    What Affects Solar Panel Degradation?

    Environmental factors are mostly to blame for panel degradation, but there are some problems that can stem from the manufacturing of the solar cells as well. The most impactful factors include the following:

    • Exposure to ultraviolet (UV) light
    • Changes in temperature
    • Changes in humidity levels
    • Potential-induced degradation (PID)
    • Solar cell defects

    We’ll discuss why each of these factors can reduce your panel efficiency in the following sections.

    Factor 1: Exposure to UV Light

    Rooftop solar panels are exposed to sunlight constantly, and the UV light, which gradually causes damage to a wide variety of materials. Included in those materials are those that go into solar cells, any anti-reflective coatings and other components. Over time, damage to these materials will naturally reduce the cells’ ability to absorb light and the protective materials’ ability to reduce losses to the environment.

    It’s difficult to quantify how damaging UV light can be to solar cells over a specific time period, but it’s likely largely responsible for the average 0.5% loss of efficiency year over year after the first 12 months of panel operation.

    Factor 2: Changes in Temperature

    All of the solar cells inside your panels are held together using adhesives and are wired in parallel to generate power and send it to your home. The points where cells are connected and soldered together all expand and contract as the temperature inside the panel changes.

    Since solar panels are under direct solar irradiance during the day and are designed to absorb sunlight, they see a much more extreme change in temperature between day and night than we perceive.

    This temperature fluctuation, called thermal cycling, will gradually weaken the connections between your solar cells and cause a dip in efficiency.

    Again, the amount thermal cycling contributes to efficiency loss isn’t specifically known. However, we expect that a good portion of the average 2.5% drop in efficiency in the first year of operation is largely due to thermal cycling.

    Factor 3: Changes in Humidity

    Changes in humidity or exposure to high humidity levels can negatively affect panel efficiency in two ways. First, if humidity gets inside your panels—which can happen if there are any manufacturing defects—the moisture can slowly change the conductivity of the silicon cells. This leads to lower production over time.

    Second, and more indirectly, high humidity levels combined with changes in temperature can cause condensation on your panels. Those small water droplets can interrupt the sunlight that normally would enter your panel for absorption, leading to decreased production in real time.

    solar, panels, lose, efficiency

    Factor 4: Potential-Induced Degradation (PID)

    PID is a loss of energy that occurs when there is a high voltage potential difference between the solar cell and other materials in your panels, including those used to wire the cells in series. PID typically stems from an issue with grounding.

    Research suggests that PID can lead to a dip in efficiency of up to 30%, making it one of the most severe issues. Thankfully, advancements in solar technology have allowed tier-one modules to resist losses due to PID and resulting leakage currents.

    Factor 5: Solar Cell Defects

    Finally, manufacturing defects in the solar cells and panels can all accelerate efficiency degradation. Some of the more common issues include microcracks in the silicon solar cells, the use of mismatched solar cell materials that promote PID, over-sized or unders-sized inverters or micro inverters and the use of adhesives that cannot stand up to the thermal cycling expected inside a solar module.

    How Will Solar Panel Degradation Affect Your Wallet?

    The science behind solar panel degradation might seem confusing, but its effect on your energy savings over time is plain and simple: the more your panels degrade and the more rapidly they degrade, the longer your panel payback period will be and the lower your overall energy savings are expected to be.

    The amount you save on your utility bills is directly correlated to panel efficiency over the life cycle of your solar power system because lower production means fewer kilowatt-hours offset and more money you’ll have to pay for energy consumption.

    Depending on where you live, your access to net metering, your local electricity rates and how much of your energy demands are met by your solar production, an accelerated dip in panel efficiency could lead to a difference of hundreds or even thousands of dollars in energy savings.

    To maximize your solar panel system’s efficiency and durability, you can use the button below to get a quote from SunPower, which manufactures the most efficient solar panels and has some of the lowest degradation rates in the industry.

    Do Solar Panel Warranties Account for Efficiency Loss?

    Yes, solar panel performance warranties account for efficiency loss and provide a maximum power loss per year throughout the warranty term. The average degradation is 2.5% in the first year and then 0.5% per year after that. That means you’re guaranteed to retain 97.5% efficiency after one year and 85.5% after 25 years.

    Since panels typically pay for themselves in around 12 years, the 25-year warranty should be plenty to ensure you come out positive over time. Most homeowners pay for their panels with energy savings and then save an additional 22,000, and the standard 25-year production warranty should be enough to reach these savings yourself.

    The best production warranty comes from SunPower solar panels, which also offers the highest starting efficiency available for residential panels. SunPower’s production warranty guarantees a maximum drop of 2% in year one and then 0.25% per year after that. That equates to 98% remaining after one year and 92% remaining after 25 years. The entire warranty term is for 40 years, which is, by far, the longest in the industry.

    Some of the lower-quality panels will have even less appealing warranty coverage than the industry average. You’ll also typically see 10-year warranties from DIY solar panel brands, as well as a faster rate of degradation within that term.

    Tips to Extend the Efficiency of Your Solar Investment

    Since panel efficiency is so crucial for maximizing savings and increasing the value of your photovoltaic (PV) system, most customers look for ways to preserve panel efficiency over time. There are four things you can do to accomplish this:

    • Avoid installing in shaded areas
    • Monitor your system after solar panel installation
    • Choose a reliable panel brand
    • Only have experienced professionals install your panels

    We’ll explain why each of these tips works in the following sections.

    Avoid Installing in Shaded Areas

    Your panels need to be exposed to direct sunlight to reach their maximum potential, so installing panels in areas that will be shaded by trees, buildings, utility lines or other obstructions will naturally reduce the amount of light and the production rate.

    However, portions of your panels that are exposed to direct sunlight will also heat up more rapidly than those in the shade. This can lead to hotspots in your panels, which can accelerate PID and leakage currents.

    Monitor Your System After Installation

    As mentioned above, hot spots in a panel can lead to efficiency degradation of the module as a whole if not addressed quickly. Hot spots can occur for a variety of reasons, including manufacturer defects, weakened connections and partial shading of your panels.

    It’s helpful to have access to a monitoring app to keep track of your production. If you notice an unexpected dip in production and immediately call for service, you could avoid accelerated degradation in your system.

    Solar installers and solar panel manufacturers that offer monitoring apps do so for free, so this tip won’t cost you anything but some time and attention to your system’s performance.

    Choose a Reliable Panel Brand

    Degradation is based on a lot of factors, but choosing a panel made by a high-quality manufacturer can insulate you from a Rapid loss of efficiency.

    Manufacturers that use cheaper materials often run into accelerated or more severe issues with PID. Things like mismatched solar cells, poor connections between cells and cracks in the silicon layers or protective components can all contribute to greater efficiency losses in shorter timespans.

    You might pay a few thousand dollars more for a high-quality panel brand, but you’ll also get anti-PID technology—like the PID elimination process that Q Cells goes through—and, likely, a performance warranty that guarantees greater efficiency over a longer period of time. We strongly recommend investing in a high-quality brand, as the panels are likely to pay for themselves several times over.

    Hire a Professional

    Finally, we strongly recommend you hire a reliable and reputable solar company to install your solar energy system. Errors during the installation process can lead to cracks in the solar cells or damage to the protective components, both of which can lead to a faster rate of degradation.

    You’ll pay a few thousand dollars more for a professional installation than you would if you installed the panels yourself, but you’re likely to see improved energy savings that should make up the difference and more.

    How Much Efficiency Loss Before Its Time to Replace Your Solar Panels?

    There’s no specific time after which you should replace your panels, so the timeline will depend on ongoing production and how that compares to your energy demands.

    Since your system will ideally offset more than you consume immediately after installation, a good time to replace your solar PV system is when you notice that your panels aren’t offsetting your consumption anymore. If you enjoyed 0 electric bills for years and are now seeing your monthly utility bills jump up, it’s probably time to replace your system.

    Some homeowners have trouble getting over the upfront cost of solar panel replacement, especially if it’s still partially functional. The average system pays itself off in just 12 years, but if your existing system would still offset at least a good portion of your bill, then the actual offset of your new system will be much longer.

    It’s worth considering that older panels come with an increased risk of fire due to less optimized equipment and a higher component failure rate. The risk of roof leaks also increases with system age and constant exposure to the elements.

    Ultimately, the peace of mind you get by replacing your system can often be worth the price you’ll pay for a new array, and you’ll have the added benefit of improved energy savings from panels with a superior efficiency rating.

    Plus, if you consider that the average system saves around 22,000 over 25 years and that a new system averages around 23,940 after the federal tax credit and other incentives, your replacement system is already almost paid for entirely.

    Panel efficiency is a crucial thing to consider when you’re purchasing panels, and degradation is just as important to think about if you already own panels. Whether you’re thinking of installing a clean energy system for the first time or want to replace an aging one on your home, you can use the buttons below to get free quotes and savings estimates from reputable installers in your area.

    Solar Panels Get Less Efficient Over Time. Don’t Worry About It

    Experts say you’re unlikely to notice your solar panels degrading over the years, and it isn’t worth waiting for more efficient panels.

    Stephen J. Bronner is a New York-based freelance writer, editor and reporter. Over his more than a decade in journalism, he has written about energy, local politics and schools, startup success tips, the packaged food industry, the science of work, personal finance and blockchain. His bylined work has appeared in Inverse, Kotaku, Entrepreneur, NextAdvisor and CNET, and op-eds written on behalf of his clients were published in Forbes, HR Dive, Fast Company, NASDAQ and MarketWatch. Stephen previously served as contributors editor and news editor for, and was the VP, Content and Strategy, at Ditto PR. He enjoys video games and punk rock. See some of his work at

    Residential solar installations have seen a spike in recent years, with many Americans considering transitioning their energy usage to renewable sources (especially in light of new federal tax credits).

    If you’re among those on the fence about solar, you might be wondering how long your solar investment will last.- and how efficient your solar panels will be in the next 20 years. The good news is your panels are likely to work just as well in the future.

    While the efficiency of solar panels does drop over time, it’s usually not a big enough change to be a major worry, according to Joshua M. Pearce, a materials engineer who researches solar power systems at Western University in London, Ontario.

    Can solar panels save you money?

    Interested in understanding the impact solar can have on your home? Enter some basic information below, and we’ll instantly provide a free estimate of your energy savings.

    When a module or a PV system fails, it would usually be from something catastrophic, such as a tree fell onto your house and busted up a bunch of your panels, Pearce told CNET.

    Here’s what you need to know about how your solar panels‘ efficiency changes over time.

    Can solar panels save you money?

    Interested in understanding the impact solar can have on your home? Enter some basic information below, and we’ll instantly provide a free estimate of your energy savings.

    What is solar panel efficiency?

    Today’s solar panels have efficiency ratings in the upper teens to lower 20s. That means when photons from the sun hit the solar panels on your roof, about a fifth of those photons are absorbed and converted into electricity. The photons that aren’t converted to electricity either bounce off the panels (like a reflection) or are absorbed, but not converted into electricity. This is because many of the sun’s rays, like those in the infrared spectrum, can’t be absorbed by today’s solar panels.

    While the efficiency of today’s solar panels may not sound impressive at face value, Pearce said the technology is actually astounding compared to the efficiency of natural systems.

    The most efficient biological conversion of sunlight into anything is under 2%, Pearce said. We are 10 times better than the fastest-growing plant that has existed on Earth before humanity got here. We’re doing pretty well.

    Ultimately, the efficiency of solar panels should not be a major concern for consumers. When a solar installer gives you an estimate for your house, they will compensate for the efficiency of each panel by calculating the number of panels necessary for your home’s power needs.

    Every single system is designed for a particular house, said Freddy Petkus, founder and owner of Critical Mass Solar, a Massachusetts-based solar installer. We do enough panels to offset your energy use no matter what kind of efficiency the panel has.

    How does solar panel efficiency change over time?

    Solar panel technology has come a long way over the past few decades, but we’re far from creating a perfect solar cell. Given these inefficiencies, solar panel manufacturers expect a degradation rate of about 0.5% a year, Pearce said, and their warranties will cover any panels that fail to meet those expectations. However, this is rare.

    When you look at the data, most modules actually degrade even less than that, maybe 0.1%, and they last much longer than 25 years, Pearce said.

    How to track solar panel efficiency

    If you want to keep track of how much electricity your solar system is producing, there’s an app for that. These apps, which most solar companies provide, also allow you to track how much energy you’re consuming. While this can be valuable information for homeowners with solar systems, you’ll have an extremely difficult time tracking the efficiency of your panels with these apps.

    The variation in how much solar energy your panels get from day to day and year to year will drown out any visible effects of degradation in panel efficiency, Pearce said. The average consumer has no chance of finding a 0.1% drop in efficiency with their system.

    If you want to invest in equipment to track efficiency, Pearce recommends the installation of DC optimizers or micro inverters on your solar system.

    Will solar panel efficiency improve in time with new technology?

    Technology inevitably gets more efficient and powerful over time. According to Pearce, solar panels won’t necessarily improve due to technological breakthroughs, but rather because of better manufacturing techniques. These advancements will lead to solar panels with better glass that can absorb more solar energy, thinner layers of metal to allow for more cells and better positioning of the metal contacts.

    efficient cells will also get darker and blacker, Pearce said, more like Darth Vader’s helmet, where nothing is coming off of it, you just see the evil on the inside as they suck all the light in, then turn it into electricity.

    You should only wait for these improvements before investing in a solar system if you want to burn your money, the experts CNET spoke to said.

    Right now in Massachusetts, the breakeven point with the major utility companies is anywhere between six to nine years to pay for solar, Petkus said. Hypothetically, if your bill is 200 a month, in 10 years you’ll have paid about 24,000 to the utility company. This is money better spent upgrading to solar.

    Treat switching to solar power much like you would any other investment, Pearce said. Analyze the rate structure of your power provider to calculate the rate of return on installing a solar system. Then, try to factor in future rate increases and inflation. An estimate of about 3 per watt to install a solar system is a good baseline. The math should speak for itself.

    Solar cell efficiencies will definitely improve, but waiting around for them won’t get you anywhere, Pearce said. This is a 25-year guaranteed rate of return with no taxes, because it’s all savings, and it’s inflation-proof.

    Which are the factors that affect solar panels’ efficiency?

    Solar power systems are considered a key tool in the energy supply for the present and future generations. Several factors have promoted the development of photovoltaics such as environmental concerns, incentives and tax deductions, a more performing and less expensive technology and the need to replace carbon fossil energy systems with renewables to ensure compliance with the objectives set by the Paris COP y limit global warming to 1.5 ° C.

    A solar cell or photovoltaic cell is a device that converts the sunlight into usable energy. The amount of sunlight that can be converted into electricity is referred to as solar cell efficiency. There are some factors that should be taken into consideration to guarantee the optimal efficiency of the solar panels.


    The temperature influences the efficiency of the photovoltaic cell due to the intrinsic characteristic of the semiconductor material. The efficiency of the solar panels increases when the temperature drops and decreases in high temperatures, as the voltage between the cells drops.

    Energy Conversion Efficiency

    The solar module has a different spectral response depending on the kind of the module. Therefore, the change of the spectral irradiance influences the solar power generation. The energy conversion efficiency is increased by reducing the reflection of the incident light.

    Solar Shadings

    Solar PV panels are very sensitive to solar shadings. Total or partial shading conditions have a significant impact rate on the capability of delivering energy and may result in lower output and power losses. Cells in a solar panel are usually connected in series to get a higher voltage and therefore an appropriate production of electricity.

    But when shading occurs, this structure presents some limitations. In fact, when a single solar cell is shaded, the current of all the units in the string is determined by the unit that produces the least current. When a cell is shaded, the whole series is virtually shaded too. To prevent the loss of energy, the installation usually includes bypass diodes.

    Bypass diodes are wired in parallel to the solar cells. When a solar cell is shaded, the bypass diode provides a current path that allows the string of connected solar cells to generate energy at a reduced voltage. Read more.

    The Orientation, Inclination, Latitude of the place and Climatic conditions

    The installation of the photovoltaic modules must take into account some factors to take full advantage of solar radiation: the orientation, the inclination, the latitude of the place, the climatic conditions. The correct consideration of these variants will help ensure that they produce maximum energy by being exposed to the greatest intensity of solar radiation for the longest period of time. Learn more.

    Operation and Monitoring

    OM services help with the management of the implementation of certain processes to avoid or mitigate potential hazards and to guarantee the optimal return on investment. Operations mainly consist of the remote monitoring and control of the PV power plant conditions and performance. Monitoring software provides access to all data collected, which can be used for different purposes: defect detection, performance analysis, improvement, predictive maintenance, and security. A good monitoring system will provide information on the production, alarms, and analytical data, in a timely, efficient, and precise manner to detect any anomaly of the PV plant. Continue reading.


    Solar panels are very durable, main warranties last for 15-25 years. However, cleaning solar panels is important to maximize the amount of light available to turn into electrical power. Making frequent physical inspections can help solar panels absorbing light effectively.

    archelios™ Suite

    archelios™ Suite is a comprehensive software solution that offers a unique approach. Thanks to its advanced computational technology, archelios™ Suite adds value to the life-cycle of any PV project: feasibility and profitability study, simulation, calculation of producible energy, complete electrical sizing, operation, and monitoring.

    The software is an efficient tool for any type of PV project.


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