If you’re wondering how solar energy works, you’re not alone. Although many of us have seen solar panels, it’s hard to picture the mechanics. In short:
Photovoltaic solar energy uses layers of semiconductors that form an electric voltage when struck by photons from sunlight. Then, the voltage created can be used to power utilities and appliances.
But, for those who want the in’s and out’s, let’s take a deeper look at solar energy and how it works below.
Types of Solar Energy
Although photovoltaic solar energy is the one most people are familiar with, there are three major solar power types. Each one works a little differently and is appropriate for different applications (1).
As we keep finding new ways to use energy from the sun, the benefits of using solar energy will only increase.
Solar Heating and Cooling
Rather than sunlight, solar heating and cooling systems use the sun’s heat to generate energy, heating or cooling air and water as needed.
We can use these technologies in homes and commercial applications to:
- Provide hot water
- Provide space heating
- Provide space cooling
- Heat swimming pools
There are several types of solar heating and cooling technologies, all of which utilize thermal energy from the sun (2).
Concentrating Thermal Solar Power
Concentrating Thermal Solar Power is a form of solar energy generally only used in large-scale power plants (3). The Solar Energy Development Development Programmatic EIS explains it like this:
Concentrating Solar Power (CSP) technologies use mirrors to concentrate (focus) the sun’s light energy and convert it into heat to create steam to drive a turbine that generates electrical power.
In addition, solar ovens use a form of this technology. However, they use CSP to cook delicious meals, and not to power a turbine.
Photovoltaic Solar Energy
Photovoltaic, or PV, solar energy is the one most of us are familiar with. When you see solar panels on a rooftop, you’re looking at a PV system (5).
Each solar panel contains between 32 and 96 photovoltaic solar cells.
Because PV solar energy is the one most used for residential applications, it’s the one most of us are interested in. Let’s dive deeper into this amazing energy technology and how solar cells work.
How Photovoltaic Solar Cells Work
As mentioned above, solar panels contain solar cells, which do the work of converting the sun’s light into usable energy using the photovoltaic effect.
The Parts of a Solar Cell
To fully understand how solar energy works, it’s important to know the layers of a solar cell from the top to the bottom:
- Protective glass
- Conductive contacts
- N-type semiconductor (usually silicon): in which electrons are negatively charged
- P-type semiconductor (usually silicon): which is positively charged
- N-P junction: which bridges the negative and positively charged layers
- Conductive base
There are several types of solar cells, including monocrystalline, polycrystalline, and thin-film, to name a few. They all share a similar structure which allows them to take advantage of the photovoltaic effect (6).
Photovoltaic Effect Explained
To explain the photovoltaic effect, you first begin with semiconductors like silicon that can act as conductors or insulators, depending on the situation.
Then, when positive and negative silicon layers are placed together, holes in the p-type silicon and electrons in the n-type create an electric field, preventing them from moving between the layers.
Next, when photons from sunlight strike the silicon layers, it disrupts the materials’ chemical bonds, creating free electrons in both layers. From there, these free electrons can cross from one layer to the other.
Ultimately, it’s easier for electrons to cross on one side or the other, giving one side a negative charge (or voltage) and the other a positive one. Then, the electrons keep circling in this one-directional (or DC) current as long as they’re exposed to sunlight (7).
To help all this sink in, here’s a great visual from Learn Engineering that further explains the process above:
How Solar Energy Integrates With Your Home
One of the many reasons why solar energy is important is that it can integrate directly with your home.
Solar panel systems create DC energy, and since your home uses AC energy, something must transform the voltage before you can use it. Therefore, the first stop for energy created by your solar panels is the inverter, which transforms DC voltage into AC voltage.
An inverter is one of the most important components of a solar panel system since, without it, the energy created would be useless.
So, how do inverters work?
DC (direct current) energy only flows in one direction, and AC (alternating current) energy flows in both directions (8). Energy.gov puts it like this:
Fundamentally, an inverter accomplishes the DC-to-AC conversion by switching the direction of a DC input back and forth very rapidly. As a result, a DC input becomes an AC output.
Then, once your inverter transforms the energy into AC electricity, the energy is sent to your home’s electric panel so you can use it to power your home.
Finally, to make things easier, you have the option to add stand alone solar products like solar powered floodlights that run independently of your home’s power grid. At the end of the day, it’s never been easier to integrate solar energy into your home.
Does Solar Energy Work Better When it’s Hot?
No, solar energy doesn’t necessarily work better when it’s hot. Solar energy works better when there’s more sunlight, so its important not to confuse the two. If it’s a hot day, but it’s cloudy outside, your panels may not receive the same amount of energy then if it was a bit cooler of a day, but clear out.
Does Solar Energy Work When it’s Cloudy?
Yes, solar energy works when it’s cloudy; they’re just not quite as efficient as when exposed to bright sunlight. While many home solar systems will provide plenty of energy despite small variations in weather like cloudiness, this is one of the few disadvantages of solar power.
Do Solar Panels Work at Night?
No, solar panels technically don’t work at night. Reason being, they need sunlight in order to produce any energy, and as you know, the sun goes down during the nighttime. Although, if you have a solar system with extra battery reserves and the sun was out during the day, you can still receive grid free power at night.
- Solar Technologies. Retrieved from: https://www.seia.org/initiatives/solar-technologies
- Solar Heating and Cooling Technologies. Retrieved from: https://www.epa.gov/rhc/solar-heating-and-cooling-technologies
- Concentrating Solar-Thermal Power. Retrieved from: https://www.energy.gov/eere/solar/concentrating-solar-thermal-power
- Concentrating Solar Power (CSP) Technologies. Retrieved from: https://solareis.anl.gov/guide/solar/csp/
- Solar Power Panel: Assembly of Solar Cells That Can Generate 230 to 275 Watts of Power. Retrieved from: https://economictimes.indiatimes.com/small-biz/productline/power-generation/solar-power-panel-assembly-of-solar-cells-that-can-generate-230-to-275-watts-of-power/
- Photovoltaic Effect. Retrieved from: https://energyeducation.ca/encyclopedia/Photovoltaic_effect
- Photovoltaic Effect. Retrieved from: https://www.britannica.com/science/photovoltaic-effect
- Solar Integration: Inverters and Grid Services Basics. Retrieved from: https://www.energy.gov/eere/solar/solar-integration-inverters-and-grid-services-basics
Hi, Im Dara. Born and raised in Farmingdale NY and I spend my time online covering alternative energy news and local developments,in the space. My mission is to help more people realise the benefits of using alternative energy. When i’m not blogging about energy you’ll find me walking my dog, working out, or practicing meditation!