We’re all trying to go green at the moment and that means using as many renewable energy sources as possible.
Solar power is a great way to do this, but what if your home or office doesn’t have a lot of exposure to sunlight? One solution is to install solar panels on your windows.
Whether you are using solar panels at home or in an RV or caravan, you are likely to wonder if they will work through glass.
The fact is that solar panels do work through glass, but there are some things to consider before using them this way.
- 1 Will My Solar Panel Produce Electricity Behind Glass?
- 2 Why Are Solar Panels Covered In Glass?
- 3 Types Of Glass Used In Solar Panels
- 4 Ways To Improve Solar Panel Efficiency
- 5 DNI and DHI
- 6 Is It Worth It To Install Solar Panels Behind Glass?
- 7 Shadings And Thermal Losses
- 8 FAQs
Will My Solar Panel Produce Electricity Behind Glass?
Solar panels will operate effectively behind glass, but there are some restrictions.
They’re made to work in direct sunlight and have special low-iron glass that permits light to pass through easily.
If you install a panel behind conventional glass or a polyvinyl window, its performance will be significantly decreased.
Fresnel Law is a scientific principle that explains how light waves change when they pass through different mediums.
The law states that when light waves encounter a new medium, they will bend.
The amount of bending depends on the angle at which the waves hit the new medium, as well as the properties of the new medium.
When it comes to solar panels, the medium that the light waves must pass through is glass.
And, according to the Fresnel Law, when light waves pass through the glass, they will bend.
This bending of the light waves decreases the amount of sunlight that reaches the solar panel.
As a result, the solar panel will produce less electricity.
The severity of the decrease in electricity production will depend on the type of glass that is used.
For example, solar panels behind clear glass will experience less of a decrease in electricity production than those behind tinted glass.
Why Are Solar Panels Covered In Glass?
Since solar glass is at the front of a PV module, it’s imperative that it serves as long-term protection against the elements.
The reason why solar panel manufacturers choose glass is because it meets the following qualifications:
- It has high visible light transmission: This is important because the solar panel needs to be able to absorb as much sunlight as possible.
- It is resistant to ultraviolet (UV) rays: UV rays can cause damage to the solar panel over time, so it is important that the glass is resistant to them.
- It is tempered: Tempered glass is a type of safety glass that is designed to shatter into small pieces if it breaks. This is important because if the solar panel is hit by a large object, the tempered glass will break into small pieces instead of large shards.
Types Of Glass Used In Solar Panels
There are two main types of solar glass:
Monocrystalline solar glass
Monocrystalline solar glass is made of a single crystal of silicon. It’s more efficient than polycrystalline solar glass, but it’s also more expensive.
Polycrystalline solar glass
Polycrystalline solar glass is made of multiple crystals of silicon. It’s less efficient than monocrystalline solar glass, but it’s also less expensive.
There is not much difference between the two types of glass when it comes to their ability to transmit light.
Ways To Improve Solar Panel Efficiency
- Have them professionally fitted
- Keep the panels clean
- Try to avoid shaded areas
- Ensure orientation, inclination, and latitude are correct
Have them professionally fitted
It goes without saying that having your solar panels professionally fitted will result in the best performance.
Not only will they be installed in the optimum position, but the company will also take into account the local weather conditions and the amount of sunlight that hits your property each day.
Keep the panels clean
Now, this won’t exactly be that easy for you to do if your panels are on the roof!
But if they’re ground-mounted or you have a solar carport, then it’s important to keep them clean.
Dirt, pollen, dust, and bird droppings can all decrease the amount of sunlight that hits the cells, which in turn will reduce the output.
I would recommend having them cleaned by your local window cleaner, providing they use the pure water system.
Try to avoid shaded areas
Solar panels need direct sunlight to work at their best, so if there are any trees or buildings that are causing shade, it’s worth trimming them back.
Ensure orientation, inclination, latitude are correct
If you have installed your solar panels yourself, it’s important to check that the orientation, inclination and latitude are all correct.
If they’re not, then it could be having a significant impact on the performance.
You can use an online solar panel calculator to work out the optimum position for your location.
DNI and DHI
Sorry to talk a bit of science, but in order to understand how solar panels work, you need to know about two things called DNI and DHI.
Direct Normal Irradiance (DNI) is the amount of sunlight that hits a solar panel when the sun is directly overhead.
Direct Horizontal Irradiance (DHI) is the amount of sunlight that hits a solar panel when the sun is at an angle.
Both of these values are important when trying to calculate the amount of electricity that a solar panel will generate.
The difference between the two is that DNI takes into account the fact that the sun is not always directly overhead, whereas DHI does not.
To get an accurate reading of the amount of sunlight that hits your solar panel, you will need to take both DNI and DHI into account.
Is It Worth It To Install Solar Panels Behind Glass?
By placing a solar panel behind a glass window, or safety glass, you are eliminating the DNI and only allowing the DHI to enter the solar panel.
The manufacturers of solar panels will never give you an accurate number for the power reduction caused by placing the solar panel behind glass.
You will often hear them say that there is no power reduction, but this is not true.
There will always be some power loss, and the amount will depend on the type of glass, the thickness of the glass, and the angle of the sun.
For example, if you live in a cold climate and have your solar panel installed behind a double-glazed window, the power output will be reduced by about 15%.
In a hot climate, the power output will be reduced by about 30%.
The power output will also be reduced if the solar panel is not installed at the optimum angle.
So, if you’re thinking about installing solar panels behind glass, it’s important to keep these factors in mind.
Shadings And Thermal Losses
We briefly covered (no pun intended) shadings earlier, but it’s worth mentioning again as it can have a big impact on solar panel efficiency.
If your solar panel is in a shady area, then it will not be able to generate as much electricity as one that is in direct sunlight.
The same goes for thermal losses. If your solar panel is not able to cool down properly, then it will also have a reduced output.
This is why it’s important to keep them clean and free from any dirt or debris.
Do solar panels work indoors?
Yes, solar panels will work indoors, but the power output will be reduced. This is because they rely on both DNI and DHI, and when they’re indoors, they only have access to DHI. The power output will also be reduced if the solar panel is not in direct sunlight.
Do solar panels work through plastic?
Solar panels will work with transparent plastic, but not all plastics are made equal. Some plastics, such as acrylic, will reduce the power output by about 20%. Other plastics, such as polycarbonate, will reduce the power output by up to 50%. So, if you’re thinking about installing solar panels behind plastic, it’s important to choose the right type of plastic.
Do Solar Panels Work On Cloudy Days?
Yes, solar panels will still work on cloudy days, but the power output will be reduced. This is because they rely on both DNI and DHI, and when it’s cloudy, the DNI is reduced. The power output will also be reduced if the solar panel is not in direct sunlight.