Solar panels have proven to be a sustainable option for electricity production. Over the years people have noticed that solar panels tend to passively cool the roof’s temperature as well.
Do solar panels cool your roof? The answer is Yes, solar panels do cool your rooftops because they block the direct passage of sun rays reaching the roof.
Sun’s rays are absorbed by the photovoltaic cells and converted into electricity while some of them are refracted back as energy losses.
When solar panels are fixed on the rooftop, they provide shade to the roof, in addition to this, there is a gap between the solar panel and the roof which allows convection and reduces the roof’s temperature.
Why Do Roofs Get Hot?
Heat absorbance and reflection depending on the type of roofing material. In hotter climates, it is advised to use a roofing material that is a semiconductor or insulator.
However, different roofing materials such as clay, metal, asphalt, wood, and bricks made of sand are used as roofing materials.
The ability of a roof to get hot is directly related to the roofing material used. If you have a rooftop made of wood or clay, it is less likely to get hot.
Similarly, if you have a rooftop made up of metal or asphalt, chances are you might get a burn while walking barefoot on it because it absorbs higher amounts of heat.
Benefits Of Cool Roofs
Solar panels are reported to lower the amount of heat energy by 38%. A cooler rooftop will resultantly keep a house cool.
Cool roofs especially in summer, will not create the need for heavy air-conditioning. This in return will be beneficial for the environment as there will be negligible CO2 emissions and greenhouse gases.
Since there is little to low sun exposure due to the installation of solar panels, there is a high chance that your roof will not get damaged by extreme weather conditions.
The supreme benefit of cool roofs is that it helps energy conservation, which means cutting down the wasteful use of energy to ensure its continuity.
How Does Solar Panel Cool Roofs?
Solar panels have proved to act as a roof cooling device along with generating electricity. Some of the cooling mechanisms include energy conversion, emittance, convection, and reflectance.
Reflectance
Solar Panels are made of semiconductors like silicon and encased in glass which is either black or in most cases dark blue. They also have an aluminum frame.
The incident ray of light tends to get reflected by both the materials i.e., the glass case and the aluminum frame.
As the heat is reflected into the atmosphere, there is a reduction in heat trapped in the surroundings of solar panels which causes a cooling effect.
Energy Conversion
Energy conversion involves the conversion of solar energy into electrical energy with the help of photovoltaic cells/solar panels.
The module of most residential solar panels has an efficiency of 20%, meaning, it lets 20% of the solar energy to converted into electricity.
The rest of the 80% of solar energy is there to heat the roof and the house potentially.
In this way, 20% of the intensity of heat is carried away by the conversion of energy.
Convection
In most houses, solar panels are installed on rooftops with a racking system. This system allows a gap of 5-10 inches or more.
This gap between the roof and the solar panel serves as a passage for airflow. The flow of air reduces the temperature of solar panels and the roof.
This results in lowering the temperature of the whole building in addition.
Shading
Well, shading is not a scientific mechanism but it is the first thought that comes to one’s mind when thinking about the phenomena of cool roofs with solar panels.
Shading or blockage of sun’s rays from reaching the roof is another way of cooling down the roof’s temperature as there is no direct exposure to the sun.
Can Solar Panels Heat The Roof?
Solar Panels have proven to be used as a cooling source apart from generating electricity from photovoltaic cells.
But solar panels work on the mechanism of absorbance and emittance which means if they absorb heat, they emit heat too.
The colour of solar panels plays a vital role in the absorbance and emittance of light rays. The dark-coloured solar panels absorb more heat and re-emit heat too.
All the heat that is absorbed into the solar panel is not converted into electricity, some of it is emitted back which causes heating of the surrounding area and roofs.
How To Optimize Roof Cooling With Solar Panels?
All solar panels work on the mechanism of reflection and energy conversion which are responsible for cooling the roof.
But solar panels tend to reduce the temperature of the roof by only 5%. There are some other factors that are involved in cooling the roofs along with solar panels.
These factors include roofing material, the distance between the attic and the roof, external insulation, and ventilation.
- It is environmentally friendly to have a roofing material that is a semiconductor. Having wooden roofs or roofs made of bricks and clay are highly likely to cool down the temperature of the roof to a noticeable degree.
- Having proper ventilation and distance between the attic and the roof also helps in the reduction of heat trapped due to emittance.
- External insulation has the primary function of insulting the house/building from severe heat and cold.
Conclusion
Solar Panels can cool your roofs directly by providing shade and indirectly with the phenomena of reflectance, energy conversion, and convection.
Along with generating electricity, shading the roof, and cooling it, solar panels have saved the roofs from extreme weather conditions like snow and hail.
Roofs with solar panels fixated at a rack stand tend to be cooler and have a prolonged life as compared to the ones without solar panels.
Shifting to greener technologies is not only reducing the combustion of fossil fuels but is also helpful in lowering the temperature of urban areas.
