Are Solar Panels Glass Or Plastic?
With climate change and rising energy costs top of mind, more and more homeowners are looking to solar panels as an eco-friendly and cost-effective way to power their homes. But when deciding whether to go solar, one of the key considerations is the type of solar panel to install. The two main options are silicon and thin-film solar panels, which have different compositions – silicon panels are made of glass while thin-film panels use a plastic-like material. Understanding the differences between glass and plastic solar panels can help homeowners choose the best option for their needs and budget.
Types of Solar Panels
There are two main types of solar panels – crystalline silicon panels and thin-film panels. Crystalline silicon panels, which account for over 90% of the solar panel market, are made from silicon wafers. There are two types of crystalline silicon panels – monocrystalline and polycrystalline. Monocrystalline panels are made from a single cylindrical silicon crystal, while polycrystalline panels are made from multiple silicon crystals fused together (Energysage.com, 2024). The silicon crystals in monocrystalline panels have a uniform look and color. Polycrystalline panels have a speckled blue color since they contain various silicon crystals.
Thin-film panels are made by depositing one or more thin layers of photovoltaic material onto a substrate like glass, plastic or metal. The main types of thin-film panels are cadmium telluride (CdTe), copper indium gallium selenide (CIGS) and amorphous silicon (a-Si). Thin-film panels are easier and cheaper to manufacture than crystalline silicon panels. However, they tend to have lower efficiency and durability (Aurorasolar.com, 2022).
Silicon Solar Panels
Silicon solar panels, also known as crystalline silicon panels, are the most common type of solar panel. They are made up of silicon cells that are encased between a glass front sheet and a polymer backing sheet (Let’s Go Solar, 2022). The silicon cells are made from silicon wafers sliced from ingots of purified crystalline silicon. Silicon can be mined from quartzite, mica, and talc, but sand is its most abundant ore source (Let’s Go Solar, 2022).
During manufacturing, silicon is melted and refined to produce a crystalline silicon ingot. The ingot is then sliced into wafers about 0.2mm thick using steel wire or a laser. The wafers are then processed into silicon cells that convert sunlight into electricity. Multiple silicon cells are assembled and electrically connected together into solar modules or panels. The individual cells are encased between sheets of glass and plastic to provide structure, rigidity, and protection (Energy.gov, 2022).
The crystalline silicon solar cells are made of silicon “doped” with other elements to form a p-n junction capable of generating electricity. When sunlight hits the solar cell, electrons are knocked loose from the atoms in the semiconductor material. If electrical conductors are attached to the positive and negative sides of the silicon cell, forming an electrical circuit, the electrons can be captured as electricity (Wikipedia, 2022).
Thin-Film Solar Panels
Thin-film solar panels are made from thin layers of photovoltaic material deposited onto a substrate like glass, plastic or metal. Unlike traditional silicon solar panels that use rigid silicon wafers, thin-film panels use nano-scale semiconductor material that is only a few micrometers thick.
The most common thin-film materials are cadmium telluride (CdTe), copper indium gallium selenide (CIGS), and amorphous silicon (a-Si). These materials absorb sunlight and convert it into electricity without needing as much semiconducting material as silicon panels. This makes thin-film solar panels lighter and more flexible than traditional panels.
Thin-film panels are also easier to manufacture at a large scale, although they tend to be slightly less efficient at converting sunlight compared to crystalline silicon panels. However, research is ongoing to improve the efficiency of thin-film solar cell materials.
Glass vs Plastic
When it comes to solar panel coverings, the main options are glass or plastic. Both have their pros and cons when compared.
Glass is more commonly used for solar panels. The main advantages of glass are:
- Very durable and can withstand impact
- Withstands weathering and UV rays
- Long lifespan of 20-30 years
However, glass has some disadvantages as well:
- Heavier than plastic
- Can shatter if impacted
- Not as flexible as plastic
Plastic solar panel coverings are becoming more popular as an alternative. Some pros of plastic include:
- Lighter weight than glass
- More flexible and impact resistant
- Often cheaper than glass
The cons of plastic include:
- Shorter lifespan of around 10 years
- Can degrade faster from weathering and UV exposure
- Less durable over time compared to glass
Overall, glass is still the most common and reliable option for solar panels, but plastic alternatives are improving and offer benefits like flexibility and weight savings.
Efficiency
The efficiency of a solar panel refers to how much sunlight it can convert into usable electricity. This is determined largely by the semiconductor material used in the solar cells. Silicon solar panels, with cells made from crystalline silicon wafers, tend to have the highest efficiency ratings. This is because silicon is very efficient at absorbing photons from sunlight and converting them into an electric current. The best silicon solar panels on the market today can reach efficiency ratings of 20-22%.
Thin-film solar panels using cadmium telluride (CdTe) or copper indium gallium selenide (CIGS) tend to have lower efficiency ratings, in the range of 10-16%. These thin-film materials do not absorb and convert sunlight as well as crystalline silicon. However, thin-film panels have the advantage of being easier and cheaper to manufacture. So while they produce less electricity per square meter, the lower cost helps compensate.
When deciding between materials, efficiency is an important consideration but must be weighed against factors like cost, temperature resistance, longevity, and environmental impact. Crystalline silicon offers the best efficiency but is more expensive, while thin-film panels sacrifice some efficiency for cost savings.
Durability
When comparing the durability of glass versus plastic solar panels, glass panels tend to be more durable and have a longer lifespan. Glass solar panels are designed to withstand exposure to extreme temperatures, moisture, and impact from hail or debris better than plastic panels.
The glass that covers most solar cells is specially formulated to be durable and impact-resistant. Typical glass panels use either tempered glass, which is heat-treated for strength, or anti-reflective coated glass, which is chemically toughened [1]. This type of glass protects the solar cells from weathering effects and provides excellent protection from hailstones. Tests have shown properly installed glass solar panels to withstand 1-inch diameter hailstones striking at 50 miles per hour [2].
Plastic solar panels, in comparison, tend to be more vulnerable to impact, heat deformation, and weathering effects that can degrade the plastic over time. Plastics can become brittle and crack after prolonged sun exposure. However, modern polymer technology is improving plastic panel durability through the use of advanced materials.
Overall, glass solar panels tend to have a useful lifespan of 25-30 years or more, while plastic panels often have a lifespan closer to 15-20 years. With proper installation and minimal shading, glass panels are the more durable long-term option.
Cost
One of the key considerations when choosing between glass and plastic solar panels is cost. According to research from Solar Manufacturing Cost Analysis, the materials make up a significant portion of the total cost of a solar panel. Silicon solar panels with glass tend to be more expensive due to the higher costs of the silicon cells and the glass casing.
Thin-film solar panels with plastic backing are generally cheaper, with estimated materials costs ranging from $0.20-0.50 per watt, compared to $0.75-1.00 per watt for crystalline silicon panels, according to the same NREL study. However, the plastic-backed thin-film panels tend to be less efficient, so more area is needed to generate the same amount of electricity. This can offset some of the material savings.
Overall installation costs for a solar system range widely, with estimates from NerdWallet putting the total between $18,000-$36,000 for an average home. The type of solar panel material is just one factor driving the total expense. While thin-film presents some cost savings on materials, the lower efficiency means a larger system size, which increases labor and permitting costs. For most homeowners, the total installed cost ends up being fairly comparable between glass and plastic solar panels.
Environmental Impact
The environmental impact of solar panels varies depending on the materials and manufacturing process. Silicon solar panels, which make up over 90% of the solar panel market, do have some negative lifecycle impacts due to the energy-intensive production process. Producing polysilicon, the main material in silicon solar panels, requires high amounts of electricity that often comes from fossil fuels. The extraction of silicon from sand also requires the use of hazardous chemicals like hydrochloric acid.
According to one analysis, the carbon dioxide emissions from manufacturing a typical silicon solar panel are estimated to be around 285 kg. The emissions from fossil-fuel based electricity over a 25 year lifespan would be around 19,000 kg. So while there are upfront carbon costs, the emissions savings over the lifespan of a solar panel are substantial.
Thin-film solar panels have a much lower environmental impact during production because they require less energy and material to manufacture. They are produced by depositing photosensitive materials on substrates like glass, meaning no hazardous chemicals are needed. However, thin-film panels tend to have lower efficiencies than silicon panels.
Overall, when comparing lifecycle impacts, solar panels are estimated to emit 3-4 times less carbon dioxide per unit of electricity generated than coal or natural gas power plants. With some manufacturing improvements and recycling initiatives, the environmental impact of solar panel materials can be further reduced.
Conclusion
In summary, both glass and plastic have their advantages and disadvantages when used as the protective layer for solar panels. Glass is more durable and efficient at transmitting sunlight, but it is heavier and more prone to breaking. Plastic like PET is lightweight and flexible but less efficient at transmitting light. Thin-film solar panels tend to use plastic while crystalline silicon panels use glass.
For most residential and commercial installations, glass-on-glass solar panels are the best choice. The higher efficiency and durability of glass outweighs the risks of breakage, and glass panels will produce more clean energy over their lifespan. However, for specialized applications like RVs, curved surfaces, or consumer devices, flexible plastic solar panels may be preferred.
When deciding between glass and plastic solar panels, consider factors like efficiency, lifespan, weight, flexibility, and cost. Analyze your specific needs and environment to determine if the advantages of glass or plastic are more suitable. With continuing advances in materials science, future solar panels may incorporate innovative coatings, nanotechnologies, or hybrid materials that combine the benefits of both glass and plastic.
