Do Solar Panels Use Heat Or Light?

 

If you are thinking of going solar, there is no harm in learning a bit about it. At least, how it is generated? For us who are not much aware of the science behind the generation of electricity from the energy of the sun by the solar panels, an obvious question is – Is the heat or the light energy of the sun used by the solar panels to generate electricity?

And since heat and light energy are almost experienced in tandem, the question becomes trickier! The following guide will in all probability answer all your queries and doubts!

How Do Solar Panels Generate Electricity?

Solar panels generate electricity with the light from the sun and not the heat. With a change in temperature, there is hardly any change in the amount of energy absorbed by the panels but the amount of electricity generated from the absorbed energy varies. The efficiency of a solar panel drops when it gets too hot or too cold. Solar panels, in fact, perform better in a bit more cold than too much heat.

The photons in natural daylight are converted by the panels for the production of electricity. Here heat has no effect. Solar panels use silicon which helps in the production of electric current from daylight.

Even if it is cloudy, it works. This is because daylight is essential and not sunlight. Obviously, with direct sunlight, the panels would definitely perform better. But modern panels have concentrators that maximize the light the cells receive with the aid of mirrors and lenses. Thus solar panels are 40% effective in cloudy weather. Here the size of panels is significant too – larger the better. The best part is that you are “going green” with solar.

Do Solar Panels Use Light or Heat Energy?

A solar panel uses both light and heat energy from the sun. But the most important part harvested by a standard solar panel is the light. The solar panels use photovoltaic effects from the harvested light energy of the sun and convert the light energy directly to electricity.

Thus it is actually the light that generates electricity and excess heat may actually deter the process of electricity production. Higher temperatures will cause a reduction in the efficiency of electricity production. Thus, though solar panels absorb both heat and light, the light is what is actually needed. But this is the norm for PV solar panels which are the standard ones. But then there are thermal solar panels that have a different style of functioning.

Are There Solar Panels That Utilize The Heat Of The Sun To Generate Electricity?

Some solar panels use the heat of the sun to generate electricity and such panels are called thermal panels. The sunlight heats up the panels which can be used to generate steam and electricity or household hot water.

But such panels are less installed in homes because their integration with water systems is quite complex and managing these are not easy. Also, they lead to a bigger discrepancy between the cold and hot days and are thus less reliable than the standard PV solar panels which depend entirely on light.

Why Is Using The Light Of The Sun To Generate Electricity More Efficient?

When you use the light energy of the sun to generate electricity it is more effective as the ultraviolet and infrared light that we cannot see is also utilized.

But the light needs optimization. Like in the case of home installations, the panels should be properly oriented to get the maximum sunlight. And when it is freezing cold weather or snowing, solar panels will use the heat to produce enough electricity only if there is optimal sunlight.

But you cannot optimize the heat coming from the sun in any effective way. It entirely depends on temperature – the degree of hotness – which is not very reliable. One other problem with heat-led solar panels is that with rising temperature the electrical resistance of the circuits increase and so more work is required to produce an equal amount of electricity.

Why Efficiency Decreases In Too Hot Conditions As Compared To Cold Ones?

The atoms vibrate faster inside a hot solar cell than in a cool solar cell. Sunlight excites the electrons within the atoms to a higher level thereby generating electricity. Excess heat causes the atoms to vibrate faster as a result of which the electrons within the atom find it difficult to get out. If this is the situation, the energy never gets converted to electric current.

If you look at it in another way, solar cells are able to produce electricity when the electrons move from a lower energy state to a higher energy state. But when a solar panel becomes hot, the difference between these two states becomes very less and so no energy is formed.

But when the panel is cooler, the electrons in the solar cell get excited due to the sunlight and easily move to a higher level of energy. This happens because the atoms are not vibrating. And so, though the electrons are moving slowly, those that move through carry more energy than those in a heated state.

How Does The Efficiency Of A Solar Panel Vary With Temperature?

The efficiency of a solar panel falls by almost 0.05% for every degree Celsius rise in temperature. But with the fall of every degree Celsius of temperature, the efficiency increases by 0.05%. Here “temperature” means the temperature of the panels and not the temperature outside. But air temperature is definitely going to affect the panel temperature.

Again efficiency depends on the hardware and the design of the solar panels. Usually the term “temperature coefficient” is used by the solar panel manufacturers for the measurement of how well a panel handles cold or heat. This is the range of temperature within which the panel can give its best produce.

Why Cooler Is Better ForSolar Panels?

The best weather condition for a solar panel is sunny, cold, and windy. In such situations, the panels get lots of energy from the sun, remain cool and the wind moves away from the normal levels of heat created within the panel itself. But definitely bitter cold arctic temperatures will obviously slow down solar energy production.

Thus cooler temperatures are actually better for the energy production of solar panels. While the warmer regions make up for the excess heat with more sunshine. Though cooler regions being away from the equator have less advantageous angles of receiving sunlight, they make it up when the sun is shining.