Whether you want to power your home, business, or just want some extra power on a camping trip, there’s a solar panel out there for you. It’s easy to be overwhelmed by the number of brands, the different types of panels, and the sheer amount of information you need to make an educated decision. We’re here to help! Solar panels are a long-term investment, it’s not a good idea to go in blind. We’ve broken down the different types of solar panels to help you make an informed decision.
Crystalline Solar Panels
Crystalline solar panels (c-Si) are the dominant solar panels on the market. They’re what you usually imagine when you think of a solar panel. They’re also called first-generation solar panels since they were the first type of solar panel. Crystalline solar panels are currently the most efficient and durable panels on the market today, though others are starting to rival c-Si panels in efficiency.
C-Si panels tend to be more efficient, expensive, and longer-lasting, meaning they also have longer warranties. They’re made with crystalline silicon semiconductor wafers, the same material used in microchips, and are housed on a plastic or metal back sheet enclosed with a metal frame and glass face. Higher quality c-Si panels have an anti-reflective coating on the glass to reduce glare, as too much-reflected light means less power output. It’s important to keep the glass clean. Over time, dust, dirt, and bird droppings can build up on the glass, which reduces incident sunlight and lowers efficiency.
Generally speaking, c-Si panels don’t do well in dappled or indirect sunlight, so it’s best to install them with microinverters, which will offset a decrease in power in case a few of the panels are covered by shade. They also tend to underperform in hot temperatures. C-Si panels are heavier than other varieties, making them harder and more expensive to install.
Monocrystalline panels (mono-Si) are widely considered the best solar panels on the market. Mono-Si solar cells are made with one single crystal of silicon sliced into wafers, giving them a uniform molecular structure that improves electrical conductivity. This gives mono-Si panels a higher efficiency and a longer lifespan than their poly-Si counterparts. Mono-Si panels tend to have about 20% to 23% efficiency, which is among the best in terms of commercially available solar panels. A typical warranty for mono-Si panels is around 20 to 25 years, though they can continue functioning for much longer if well maintained. They’ve actually been known to generate power for up to 40 years.
Given that they’re the best panels on the market, they are expensive, but you’ll be paying for quality. Since the efficiency is so high, it takes fewer solar panels for a given output compared to other types of panels, which is good for those who lack space. Many also consider monocrystalline panels to be aesthetically pleasing, having a uniformly black or navy blue appearance.
Polycrystalline panels (poly-Si) are similar to mono-Si, the difference being that they are made of smaller pieces of silicon crystals that have been melted together. Polycrystalline panels are recognizable by their light blue color, and the solar cells have a flaky texture. The manufacturing process means that poly-si solar cells don’t have the uniform crystalline structure seen in mono-Si cells, and so have lower efficiencies as it’s harder for electricity to flow. Efficiencies for poly-Si panels tend to hover between 15% and 20%, though higher quality panels are beginning to rival mono-Si. They also have shorter warranties compared to monocrystalline panels, with warranties usually between 15 and 20 years, but like mono-Si panels, they can still function long after their warranty ends. Poly-Si panels can function for up to 30 years if they’re well maintained.
Poly-Si panels are cheaper than monocrystalline, which has given them a larger market share. Many are perfectly satisfied with the performance and lifespan. If you have a lot of roof space or are building a ground-based solar array, poly-Si panels could be easier on your budget.
Thin-Film & Flexible Solar Panels
Thin-film solar panels are exactly what they sound like: a very thin solar panel. Also known as second-generation solar panels, thin-films are made of a thin strip of semiconductor material, and can either be housed in rigid frames similar to c-Si modules, or can be made as flexible panels. Thin-film panels are lightweight, flexible, and can go where crystalline panels can’t. Their flat appearance allows them to blend onto walls and roofs, earning them major points for their aesthetics. Flexible panels are also great for vehicles, RVs, and vessels, as they can bend and fit onto curved surfaces. Thin-film panels also tend to be more affordable, both in price and installation costs.
Thin-film panels do have quite a few downsides, like their lower overall efficiency. They’re also easily damaged since they’re so thin. Due to the lower efficiency, you’re going to need more space per given unit of power. They also tend to have lower lifespans and warranties. Flexible solar panels, specifically those of lower quality, tend to degrade under hot temperatures and undergo what’s called delamination. This is when the solar cells detach from the plastic laminate. Larger solar arrays are more cost-efficient as the lower costs offset the lack of efficiencies on a larger scale.
Cadmium Telluride (CdTe)
Cadmium telluride solar panels, called CdTe for short, are the most common thin-film panels. Most CdTe panels aren’t flexible but are instead housed in an all-glass case. The company First Solar is the leading brand in CdTe panels, and is currently spearheading the research. The average efficiency for these panels is around 16% to 18%, though experiments have achieved efficiencies over 20%. They have a better heat response than c-Si panels and are able to sustain their efficiency in hot climates. Their lifespan rivals that of the best poly-Si panels, with warranties of around 20 to 25 years. They are also cheaper than c-Si modules.
Despite being thin-film panels, not many manufacturers make flexible CdTe panels, though they do exist. One of the major downsides to CdTe is that they contain cadmium, which is toxic to people and the environment. This puts off a lot of prospective buyers. Luckily, CdTe modules have to sustain serious physical damage to release the toxic chemicals. Tellurium, the other element in CdTe panels, is in very limited supply and is akin to platinum in its rarity in the Earth’s crust. A shortage of tellurium can put the brakes on CdTe solar panels. Manufacturers are aware of these shortfalls, and run recycling services for CdTe panels, which properly dispose of hazardous waste and recycles the rare minerals. CdTe modules are cheaper than some c-Si panels, but cost more than a-Si.
Amorphous Silicon (a-Si)
Amorphous silicon panels (a-Si) are similar in chemical composition to c-Si panels, but instead of the crystals, the silicon molecules have no defined structure. These solar panels are at the lower end as far as power output goes, averaging between 11% and 15% efficiency, though they tend to be quite affordable. A-Si panels are often flexible and are encased in bendable plastic. This makes a-Si panels versatile and great for recreation. They can be attached to RVs and boats without adding too much weight, and they can easily be installed on curved surfaces. The flat profile is also great for aesthetics. They can be installed on a roof and remain unseen, or they can add to the design of the building if they are visible. Compared to c-Si panels, a-Si solar panels do relatively well in indirect sunlight, which helps them maintain a stable efficiency throughout the day.
The main downsides to a-Si panels are the lack of efficiency and short lifespan. The average warranty on an a-Si solar panel is around 15 years. Since they aren’t very efficient to begin with, the panels can lose their functionality as the power output starts to drop. Though flexibility is their main appeal, it could also be a downside. The soft plastic material is prone to damage from sharp objects, and if the panel is bent or folded too much, you can damage the solar cell. Lower quality a-Si panels may also undergo UV degradation, where the plastic gets cloudy and discolored over time, and will eventually result in delamination, where the solar cells detach from the plastic laminate. Note that this only happens to solar panels that have a PET coating, which degrade in hot temperatures. EFTE coatings are found on higher quality panels and are resistant to high temperatures.
Copper indium gallium selenide solar panels, or CIGS for short, are known for their high absorption efficiency. In laboratory settings, CIGS solar cells have achieved efficiencies around 20%, which would make them the most efficient thin-film PV technology available. But in practice, the average efficiency for CIGS solar panels sits between 12% and 17%. The highest quality CIGS modules will rival poly-Si in efficiency. CIGS are also known for their versatility due to the thin layer of semiconductor material required. CIGS can be applied onto glass, flexible plastic, steel, or aluminum, and many CIGS panels are flexible.
On the downside, CIGS solar panels do contain small amounts of the toxic metal cadmium, though not to the extent that CdTe does. CIGS solar panels are also very expensive, which is why they’re not very popular. Many find that other panel types are more cost-effective. Quite a few manufactures of CIGS solar panels have gone bankrupt. They have decently long lifespans, usually backed by a 25-year warranty.
Experimental & High-Efficiency Panels
Researchers and engineers are fast at work on new and experimental materials that can reach higher efficiencies than first and second generation solar panels. These are the third generation of PV technology, and while they aren’t yet commercially viable, it won’t be too long before we see experimental solar panels on our homes and backyards. Some of the more notable third gen solar technologies are listed below.
Multijunction & Concentrator PV
Whereas all of the solar panels listed thus far are single junction, scientists are working on what’s called multijunction solar panels. MJ solar cells use a stack of different semiconductor materials to catch a wider range of wavelengths, which gives them higher efficiency. They average around 30% to 35%, though some have reached efficiencies around 45%. Multijunction solar panels are usually coupled with concentrator technology, which uses curved lenses and mirrors to amplify and concentrate the sunlight onto each individual solar cell, which greatly improves efficiency. MJ technology is commonly used in high-tech operations, like spacecraft, where they can take full advantage of the unfiltered sunlight in outer space.
Perovskite solar cells are a potentially cheap and highly efficient thin-film technology that can be used in a variety of applications, from large-scale solar farms to powering individual vehicles. They currently have efficiencies of around 22%. The major limitations for perovskite are based on the lack of stability, as the material tends to break down under certain conditions.
Organic PV, also called OPV, are an experimental class of PV cells that use organic polymers or molecules to generate electricity. A major upside is the variety of different materials which can be used to create OPVs, as well as the possibility of transparent solar cells, but they lack long-term stability and suffer from low power outputs. The majority of OPVs that have been created are quite small, being the size of a quarter. OPV efficiency stands around 13%.
Finding a solar panel that’s right for you
With so many different solar panels out there, it can be hard to make the right choice. We can’t stress this enough, solar panels are a long-term investment, and you should put a lot of thought into what kind of solar panels you’re going to invest in. You’re going to have them for at least 25 years, so make sure you do a thorough cost/benefit analysis to make sure that you’re making the right choice. Here are the major factors that should influence your decision.
Costs might be the number one factor in your decision. Remember that while you may be on a budget, you should never, ever, buy low-quality panels. They break easily, are less efficient, and won’t last very long. In other words, it’s going to cost you more in the long run. It’s always better to go with higher quality panels, it’s simply more cost-efficient. It’s also good to remember that different types of panels have different installation costs as well.
Efficiency is tied to cost. More expensive panels are usually going to be more efficient. It’s wise to overestimate your power needs, as any extra electricity can be stored in a battery bank or earn you rebates from your local power company. Remember that efficiency decreases with time. Although it happens slowly, after 20 years your system might not provide the power you need. Click here to learn more about solar panel efficiency.
Space & Weight
You’ll need to factor in the amount of space that you’ll be working with. Remember that higher efficiency panels take up less space for a given power output, and vice versa. Weight is also a major factor when shopping for the right solar panel. C-Si panels weigh more, while thin-film panels weigh less. Keep that in mind when choosing between ground or roof-based arrays.
Will the PV panels power your entire home, or simply supplement your power supply? Are you only going to power a few appliances? Are you looking to use them for recreational purposes like boating or camping? Make sure you’re buying the right panels for your needs.
Different types of solar panels have varying tolerances to extreme heat or cold. Some panels do better in cloudy conditions, and if you live right on the coast, the salty air can corrode your solar panels. Find out what panels do best in your local climate before making a decision.
Aesthetics may be a luxury for some, but if you can afford it, then why not? If you want to make sure your solar panels add to the aesthetic value of your home, then you’re probably going to be paying more. Though this might not be a bad thing, as some of the most efficient solar panels tend to be the best looking.
Frequently Asked Questions
C-Si panels, or first generation panels, are the dominant PV panels on the market today. They use silicon wafers to generate electricity. Thin-film, or second generation panels, are known for their flexibility and flat appearance.
Monocrystalline panels are the most efficient commercially available solar panels. They usually have efficiencies between 20% and 23%.
Mono-Si panels are more costly and efficient, and have long lifespans, while poly-Si panels are cheaper but slightly less efficient. Due to their cost, poly-Si panels are more popular.
CdTe are the most used type of thin-film panel, and are the only type that isn’t flexible. A-Si panels are known for their flexibility and flat profile, but suffer from low efficiency. CIGS panels are flexible, and have longer lifespans and higher efficiency than a-Si, but the high cost is a major hindrance.
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