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Can Solar Panels Work Through Clear Plastic?

Can Solar Panels work through clear plastic? Many people wonder this when they are looking to install solar panels on their homes.

The answer is yes! Solar panels can work through a lot of transparent materials, including plastics and glass.

In fact, most solar cells that you see in the market today will come with a protective layer that is made out of either glass or polycarbonate. This layer protects the cell from shocks, scratches, and debris while also allowing light to penetrate it.

Solar panel manufacturers design their products considering the solar panel is protected by a layer of glass or other transparent material they have chosen by themselves.

Adding an extra layer of clear plastic or glass on top of the solar panel reduces the amount of light that passes through the solar panel, resulting in a decrease in system energy efficiency.

Depending on the type of plastic, thickness, and amount of air gap, energy efficiency can drop by up to 10%.

This happens because of the following reasons:

  • Glass and clear plastic materials have a different refractive index than air.
  • A clear plastic layer adds an extra distance of light path that needs to be traveled, causing the angle of incidence between the sun’s rays and solar panels to change.
  • The air gap between the plastic layer and solar panel may encourage water droplets to form creating a barrier that reduces the amount of light passing through and reaching solar cells.
  • The additional layer will prevent the Antireflective coating (ARC) of the solar panel to not work efficiently since there is an additional surface that the light is refracted from one to another.

Why would a homeowner want to add clear plastic on top of the solar panel?

To have an additional layer of protection (aka lamination)

A homeowner may want to install clear plastic on top of the solar panel to protect it from shocks and debris. Even though most solar panels are made of tempered glass, it is still possible for something to damage the panel.

A clear plastic layer will provide an additional layer of protection and guard against anything that could cause damage.

To provide clear protection for a roof or on a patio.

In some cases, the homeowner wants to cover the roof or install solar panels on a patio with clear protection.

Clear plastic works well for this type of application because it protects the roof or patio from any debris that may fall on it while also allowing light to pass through and reach the panel underneath.

What factors affect energy efficiency applying a new layer on a solar panel?

The thickness of the plastic layer

The thickness of the plastic layer influences energy efficiency because the thicker it is, the more difficult it is for light to pass through. If an additional layer is planned, it is recommended to get a thin version of the material, such as polycarbonate film.

The thickness of the air gap

Installing the same clear plastic right on top of the panel or a few meters above the panel will result in different light transmissions.

The air gap between the solar panels and the plastic will also have an effect on how much of the sun’s rays can pass through both layers. In order to maximize this, you should put as little space as possible between them.

If you want to cover a solar panel’s surface with clear plastic try not to leave any air gap in between the panel and covering film as it may attract water droplets or fogginess to form reducing the amount of light that can pass through.

The thicker the air gap, in between the panel and the covering film, the higher drop in efficiency the solar panel will experience. Therefore, it is always best to keep the air gap as little as possible.

The surface of plastic material

The surface quality of the plastic material has also an effect on how much light is able to pass through.

For example, a plastic film with a smooth finish will allow more light to pass through as opposed to a film with an uneven finish. This is because the smooth surface will allow for less light reflection and more light transmission, due to its polished nature.

If you are installing clear plastic on solar panels then it is important to consider all of these factors before getting started and working out your installation plan accordingly.

Optical properties of the plastic material

Every material has unique optical properties, and plastic is no exception. Plastics have a refractive index that can change from one material to another.

In addition, their ability to reflect light can also vary depending on which wavelengths are being reflected.

Knowing the optical properties of the planned plastic layer will help you to determine how much light will be able to pass through the material.

As earlier said, not all types of plastics are the same. The plastic that you choose will determine how much light can pass through it and whether or not you’ll get a good performance from your solar panels.

The best types of materials to use when making solar cells out of clear material is polycarbonate, acrylics, glass, Plexiglas™ (PMMA), fused silica glasses(quartz), and sapphire wafers in some cases.

Each one has its own plus and minus depending on what type of application you are looking for, and what environmental conditions your panels will be exposed to.

Test Different Plastic Materials Yourself

You can test the power output of a panel using a digital multimeter by measuring the voltage and amperes generated by a solar panel.

Test these values with and without the cover to see how much power is lost if you laminate your panels with a specific cover.

The test is pretty straightforward to do. Simply place the panel under direct sunlight and measure the voltage of each type of plastic at a certain angle. You can ideally position the solar panel flat position at an angle parallel to the ground.

The best time to do this experiment is on a sunny day at around noontime when the sunlight is coming from right above.

Doing this experiment, attach the plastic layer to the glass of the solar panel with transparent tape leaving as little air gap in between the panel and the plastic as possible.

This is to ensure that the least amount of light energy gets lost on its way through the plastic cover, which would skew your results.

Make sure to take as many measurements as possible to get an overall average.

If you are unable to do the test yourself you can employ a qualified third-party engineering organization that can perform the test for you.

If the power loss is significant you may want to choose an alternative option.

What types of plastic covering Most common types of plastics used to do different types of plastics have different?

Polycarbonate

Polycarbonate is a transparent plastic that has a high degree of chemical resistance and is used in solar panel manufacturing as a substitute for glass. It will not shatter and can withstand storms, snow, and stray volleyballs, among other things.

Polycarbonate has 200 times the impact resistance of glass. While it is a much stronger material, polycarbonate is actually lighter than glass, making it easier to maneuver and install.

It will have all of the benefits of glass, such as transparency and a pleasing appearance while being much stronger and lighter.

Glass fiber-reinforced polyester (GRP)

Glass Reinforced Polyester (GRP) also known as fiberglass. Although fiberglass appears to be any other type of glass, it is not. Glass is an amorphous solid, and often transparent substance created by melting sand with a mixture of soda, potash, and lime.

Fiberglass, on the other hand, is silica-based glass extruded into fibers with a length at least 1000 times bigger than its width. It has a high strength to weight ratio and is resistant against harsh weather conditions like UV rays, oxidation & corrosion.

Plexiglas™ (PMMA)

Plexiglass, also known as Poly(methyl methacrylate) or PMMA, is a type of plastic, specifically, a clear acrylic sheet is great for outdoor applications because it has good optics, resistance to degradation over time from exposure to ultraviolet light, and weathering.

Acrylic

Acrylics are also extremely clear but they don’t have the impact strength rating like polycarbonate does so they can chip more easily on a rooftop with debris flying around outside.

Acrylic is more light-transmitting than glass. Acrylic can transmit up to 92% percent of visible light. Whereas mineral glass transmits between 80% and 90% percent of visible light, depending on the type of glass and manufacturer.

Glass

Glass obviously offers excellent transmission properties as well as sufficiently durable if it is specifically manufactured for solar panels.

Glass has high costs and lacks the impact resistance of polycarbonate. Also, its optical properties are inferior to those of acrylic.

Important to note: Plastics have varying degrees of flammability; consequently, in applications where a fire hazard exists, additional care should be taken by utilizing materials with suitable fire resistance and/or proper design.

Conclusion

Solar panels can work through clear plastic or glass. However, the additional layer between the light source and the solar panel will reduce the amount of light that reaches the solar cells. This will inevitably cause a reduction in energy production.

If you are considering an additional layer on top of your solar panel, or maybe a transparent roof above your solar panels you should consider if the benefits of this outweigh the loss of energy efficiency.

but acrylic has better optical properties and is lighter. Glass can transmit more visible light than most types of plastics and offers high durability if it is manufactured for solar panels.