Fact Checked

What is Solar Glass?

Sheryl Butterfield
Sheryl Butterfield
Sheryl Butterfield
Sheryl Butterfield

Solar glass is a type of window and building material that is designed to block radiant heat transfer, which is basically the amount of heat from the sun that passes through the glass and into whatever space is on the other side. This type of glass is most commonly used in the windows of office buildings and homes, though sometimes it is also used in automobiles and in industry, often in the panels of warehouses or machinery that is exposed to a lot of solar radiation. There are a number of different coatings that can be applied, each with its own specifications. Most are designed to reduce heat absorption and improve insulation, both of which can reduce energy costs.

Basic Concept

Solar glass may be used to lower energy costs.
Solar glass may be used to lower energy costs.

In essence, solar glass is the combination of solar technology and standard window glass. Most of these windows don’t look any different form their more traditional counterparts; they’re just as clear and usually allow the same amount of light in. What they don’t usually allow in, or at least don’t allow as much of in, is radiation, which is the energy put off by the sun. This is achieved through an invisible coating that’s applied to the glass before it’s ever installed. Most of the time this coating is permanent and is designed to last for the life of the glass.

Why They’re Used

This type of glass is usually designed to reduce heat loss but allow sunlight in for warmth, a concept also known as “solar gain.” There are a couple of reasons why this is important, but reduced energy costs are a big factor. Windows are an important source of natural light, but they can also be tough to insulate. The outside elements, be they hot or cold, often penetrate window settings much more easily than walls or doors, and a lot of this has to do with the permeability of the glass itself.

Glass that has been coated so as to maximize the sun’s energy can help a lot when it comes to energy retention, and these types of high-performance glass products are used across many industries. Recent advances in solar technology, at least where glass is concerned, include laminated products that boost solar power. This concentrating solar power (CSP) reflectivity provides efficiency and durability.

How They’re Made

Glass windows coated with a low-emittance (low-E) coating block radiant heat transfer. This lowers the amount of heat that passes through a window. Low-E coatings are nearly invisible, and are usually made up of layers of metal or metallic oxide on a glass surface.

Depending on energy needs, different types of low-E coatings allow for high, moderate, or low solar gains. In layered glazing, heat can be transferred between panes of glass, usually passing from warmer to cooler. Putting a low-E coated pane in the space between layers of glass helps block that heat. Window technologists in the past filled this gap with air or dry nitrogen.

Coating Options

Today, argon and krypton gas are most commonly used between panes, which has improved window performance. Both gases are nontoxic and nonreactive. Krypton is more expensive than argon, so some manufacturers combine the two gases to improve thermal performance at a more reasonable cost. Double-glazed windows with an argon gas fill between panes of low-E-coated glass are called pyrolitic, which means “hard coated.”

Different Varieties

Glass with high solar gain is best suited to windows in cold climates. By contrast, low solar gain, or spectrally selective, low-E glazings are more beneficial for buildings and homes in warm climates. These products reduce heat loss in cold weather, yet also reduce heat gain in hot weather. Spectrally selective solar glass out-performs most tinted and reflective glazings. The level of visible light let in is usually high in proportion to the amount of heat reduction.

For climates that require both heating and cooling during different seasons, all levels of low-E coating can result in lower annual energy bills. Solar-optimized glass is practical for windows, doors, and skylights. Commercially, it is used for the top surfaces of thermal collectors and photovoltaic modules. Solar glass is almost always colorless, but in most cases it can be patterned for optimal solar energy transmission.

Sheryl Butterfield
Sheryl Butterfield

Sheryl is a freelance writer based in Denver, Colorado. She specializes in articles about environmental issues, renewable energy, and parenting teenagers.

Sheryl Butterfield
Sheryl Butterfield

Sheryl is a freelance writer based in Denver, Colorado. She specializes in articles about environmental issues, renewable energy, and parenting teenagers.

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Discussion Comments


@Drentel - Some companies offer the argon filled window as their basic energy efficient window. You actually have to pay more for a window without the gas. I know, this makes absolutely no sense.


You have to careful when you purchase the windows with the various types of gas that is supposed to help with the performance of your energy efficient windows. These gases make the windows considerably more expensive, and for the most part, the consumer has no way of knowing for certain that the gas is actually trapped between the glass.

If the window loses the seal and the gas escapes then the person who bought the window is left with a basic window with no performance-enhancing gas, and he paid more money for something he is not getting.


We have a bank of windows in the room that we use as a den or TV room in our house. The entire east wall in the room is lined with windows. As you can imagine, during the summer when the sun rises and throughout the morning hours the heat from the sun as it comes through the windows is rather intense.

When we decided to replace the old windows with new energy efficient windows, the salesman asked whether we wanted some type solar glass film or some type of tinting to block the sunshine, and keep the house cooler.

We considered choosing this option, but then we thought of how nice the heat felt in the winter when the weather was cold outside, and how this heat from the sun helped us save on heating costs.

We decided to go with the basic windows. They were less expensive. Now, we just put sun blocking curtains up during the summer and then leave the windows uncovered the rest of the year.


i agree that solar glass is very useful and solar glass is very nice to see.


where can i get a piece of solar glass approx 26" x 23" 1/2" thick for an inset top on table? Thanks.

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    • Solar glass may be used to lower energy costs.
      By: atm2003
      Solar glass may be used to lower energy costs.