Do Solar Panels Use Heat or Light?

Solar energy was first used to light fires in the 7^th Century BC. The very first solar cell to power an electrical device wasn’t invented until 1954. These photovoltaic cells made from silicon, mark the beginning of solar energy technology as we know it today.

Solar is a relatively young technology. It is so young only a small percentage of the world’s population is confident about what they know about it.

Is it any surprise that there is confusion and some misinformation as to the science behind solar energy? Indeed, one of the biggest questions about solar, and the subject of today’s article, is do solar panels use heat or light to generate electricity?

Do Solar Panels Use Heat Energy?

Solar panels do not use heat energy. Instead, solar panels rely entirely on light to produce the current that can power electrical equipment or be stored in a battery for later use. Heat, contrary to what most people assume, does not play a role in energy production.

Solar panels absorb both light and heat energy from the sun. However, only 20% of the light absorbed by a solar panel is converted into electricity. The heat is absorbed and also radiated as a by-product of the solar panel’s energy conversion process.

This is where we get the concept of solar panel efficiency. The efficiency of a solar panel is a measure of how much energy, in the form of sunlight, can be converted through photovoltaics into usable electricity. The rest is lost as unusable heat energy which cannot be converted. (Source)

Also. find out if Solar Panels Radiate Heat?

In this article, we’ll look at the relationship between solar panels, heat, and light. By the end of the article, you will know what part heat and light play in solar energy production.

How Does Heat Affect Solar Panels?

It might seem counterintuitive but heat reduces the ability of a solar panel to convert solar energy into electricity. This goes against what most people think when asked how solar works.

One reason for the negative effect of heat on energy output is that heat increases the electrical resistance of the circuits of a solar panel.

This forces the panels to work harder to produce as much electricity.

Ideally, solar panels need to remain as cool as possible while remaining in direct sunlight to produce energy. Under standard test conditions, solar panels are found to perform best at a temperature of 25°C. With every degree increase in temperature, the solar panel’s performance starts to degrade and its energy output decreases. (Source)

For more on this topic, check out our post titled “Do Solar Panels Overheat? Is it a Big Deal!“

What happens to the heat?

The heat from the sun is not used in the chemical process that converts light into energy. What then happens to it? Most of the heat is reradiated into the atmosphere. Some of it is stored by the solar panel and its components as latent heat while some is distributed into the surrounding air.

Are There Solar Panels that Use Heat?

There is some degree of confusion around this but here are the facts. All solar photovoltaics use sunlight. They do not use heat. What we do have are solar thermal collectors which use sunlight to heat water.

It’s important to stress that even though they are called thermal solar panels this is a misnomer that creates confusion because of the use of the word “thermal”. They are thermal solar panels, not in the sense that they use heat, but that they generate heat through the use of sunlight.

Fortunately, there is ongoing research to try to harness the heat energy that is lost by solar panels. Solar thermophotovoltaic devices or STPVs would double the amount of energy produced by solar panels. This is if they finally make it into commercial production.

An STPV captures both light and heat before reflecting the light to a nearby solar cell which converts the light to energy. At present, STPVs are still in the developmental phase but it is hoped that they may be production-ready in the future. (Source)

What Charges Solar Panels Light or Heat? how Does It Work!

Solar panels get their energy from light. This is primarily in the form of sunlight. Solar panels can, however, also produce energy from artificial light sources like light bulbs. While only the light is used, the heat remains as an unused by-product.

Find out more and check out our article titled Do Solar Panels Use UV Light?

How do solar panels work?

Solar panels have a chemical process similar to that of plants. In plants, the process is called photosynthesis. In solar panels, the process is known as the photovoltaic effect. These processes are similar in the sense that they both produce energy from light.

The difference is that with solar panels the solar energy is converted into electricity. Here is a fun fact mentioned at the beginning of the article. The earliest known use of solar energy was to make fire! Magnifying glasses were used in ancient Rome to light fires.

Today, however, solar panels are used to power and operate everything from simple devices like handheld torches to more complex equipment like solar power plants and even entire space stations.

How a solar panel converts light into energy ?

• Sunlight is energy-dense. It carries light particles. The technical or scientific name for the light particles is photons. It is these photons that create the electric charge in a solar panel.
• A solar panel has two connected layers made from semi-conducting material. The top layer is known as the Negative-Type or N-Type layer. The bottom layer is known as the Positive-Type or P-Type layer. The top layer is “doped” to create free electrons that will be responsible for the conduction of current in the solar panel.
• When photons are absorbed by a solar panel, they charge the free electrons in the Negative-Type layer. These charged electrons then make their way to the Positive-Type layer where there are fewer electrons or “holes” that must be filled. This creates the flow of an electrical current.
• The flow of electrical current is what then charges a solar panel and powers an electrical device or battery. From sunlight we then have electricity.