Almost 20% of the United States’ electricity generation comes from renewable sources. However, with the global climate crisis at an all-time high, the push for clean energy to power the future has gained momentum. As the cleanest and most reliable source available, solar energy is at the top of our pursuits.
Solar energy adoption is growing, which begs the question “how do solar panels work.” Continue reading for everything you need to know about the renewable energy source.
What Is Solar Energy?
Solar energy is radiant heat from the sun, harnessed using a range of technologies. The process typically involves converting thermal radiation from sunlight into energy. This happens through the photovoltaic (PV) effect, in which the semiconductor of a solar cell absorbs thermal energy and releases current to the power outlet.
The Solar Energy Industries Association (SEIA) says solar energy is the “cleanest and most abundant renewable energy source available.” While it just recently grew in popularity over the last 30 years, solar energy, alongside wind power, makes up a fifth of the US energy generation. With feed-in tariffs and government incentives, solar is set to overtake global reliance on oil over the next three decades.
PV systems and concentrated solar power are two common ways of harnessing solar energy. Photovoltaics typically involve panels of solar cells aligned in series that direct current to a battery. Concentrated solar power uses mirrors to focus sunlight into a receiver. Other forms of collecting solar include passive techniques such as light dispersion, solar water heating, and intentional orientation.
How Do Solar Panels Work?
The most recognizable solar energy collection method is solar arrays. These systems consist of solar cells that convert thermal radiation into electricity. Their ability to transform light energy relies on their semiconductor material, which partially allows atoms to pass through it. The material collects the photons from sunlight and transfers energy to the material’s electrons. Charged electrons then travel along a current to the output and store in a battery as electricity.
For maximal collection, several cells connect to create a panel. These panels feature a reflective glass layer that helps direct sunlight into the solar cells. Each panel comes with a varying number of cells, depending on the amount of wattage required. However, not all cells are made the same, and their semiconductor material can guide several characteristics.
Types of Photovoltaic Cells
When trying to understand the question “how do solar panels work,” one of the critical determinants is their cell’s composition. The choice of semiconductor material depends on:
- Bandgap (the light wavelength that the cell can absorb)
Silicon photovoltaics are common in commercial and residential solar panels. They are made of quartz sand, one of the most abundant materials on Earth. Their ease of manufacturing and acceptable bandgap makes them a desirable product for everyday use. Apart from silicon, these panels sometimes use cadmium telluride or copper indium gallium diselenide as semiconductors.
Perovskite PVs coat a substrate in thin layers of semiconductors, which makes them easier to manufacture. However, the lifespan of these cells is shorter than silicon, so their applications are limited while the technology continues to develop.
For the highest efficiency, NASA engineers are working with multijunction photovoltaics. These use several layers of cells made of different semiconductors to widen the overall bandgap of the system. Some studies show multijunction PVs have a 45% efficiency, nearly double that of commercial silicon panels. However, they’re expensive to produce, which limits their use to space and military applications.
Large solar farms typically use concentration photovoltaics, which combine semiconductors with mirrors to direct sunlight into a central cell. The result is less PV material usage, making them affordable in large-scale systems. However, the technology is fairly new. So, it’s likely you won’t see them anywhere below the municipal level for now.
How is Solar Panel Output Calculated?
Understanding the components of a solar panel gives us an idea of how they convert sunlight into electricity. However, not all solar panels produce the same amount of power. It’s helpful to know how to calculate their output (watt-hours). To do this, we need to know a couple of numbers:
- The panel’s wattage
- The peak sun hours
What Is Wattage?
A solar panel’s wattage is the maximum number of watts in an hour. Each panel’s wattage is different, typically depending on the number of cells and the semiconductor used. Most residential solar panels have 36 to 144 cells, which average around 100W and 400W. You can find the manufacturer’s wattage rating listed on the panel.
What Are Peak Sun Hours?
The total wattage a solar panel can produce in a day is determined by the amount of peak sun hours in a location. These represent the number of hours in a day when the sun is at its most intense (an average of 1000W/meter squared). This number varies with an area’s geography. You can find the average peak sun hours in your location using a sun chart.
How to Calculate Solar Panel Output
Calculating a solar panel’s watt-hours is pretty straightforward. Simply multiply the wattage by the number of peak sun hours. For example:
Let’s say we’re figuring the watt-hours of a 300-watt panel located in Massachusetts (which has 3.84 peak sun hours). The calculation would look like this:
300 watts x 3.84 peak sun hours = 1,152 watt-hours per day
For commercial and residential purposes, solar output reads in kilowatt-hours (1kW = 1,000W). In the scenario above, just divide 1,152 by 1,000. The 300-watt panel in Massachusetts can produce 1.2kWh per day.
What Factors Influence Solar Panel Production?
Amount of Solar Cells
The amount of power a solar panel can produce is parallel to its number of solar cells. Simply put, the more solar cells a panel has, the higher its wattage. Standard silicon panels typically come with 60-72 cells and come rated for about 250 watts. Of course, the semiconductor material used could require more or less cells to produce the same amount of power.
Type of Solar Panel
Photovoltaics are either monocrystalline (mono) or polycrystalline (poly). Mono panels feature solar cells made of a single silicon crystal. These are typically more rigid and provide higher efficiency. Poly panels have cells made of several blended crystals. They’re flexible in nature, which gives them a wider range of uses. However, they’re typically less efficient than mono panels.
Position and Location
A solar panel’s orientation can have a noticeable effect on its output, with its relative position to the equator being another major influencer. For example, the United States is in the northern hemisphere, where the sun is always southward. So, south-facing panels will produce more power than those facing north.
The least amount of shade can have a dramatic impact on the entire panel’s output. Every cell connects to the same current. Think of this system like a string of Christmas lights. If a single cell is shaded, the panel can only output as much as that covered PV can convert.
While it’s imperative to keep solar panels totally exposed to the sun, exposure to extreme heat can also reduce their efficiency. Blistering summer days can drop a panel’s energy production by as much as 10%. To accommodate this, consider differently colored panels to alter their heat absorption.
How Do Solar Panels Work? Further Reading
Diving deep into the question “how do solar panels work” gives us an idea of how renewable energy offers an alternative to oil. With years of research and implementation, solar is finding its way into a wide variety of industries. For more on how this technology enhances our lives, check out the articles below.
The 5 Best Solar Lanterns for the Modern Camper – Whether out in the forest or as an emergency light source, solar lanterns are reliable devices.
Aptera Motors: Guide to the Solar Electric Vehicle Manufacturer – Aptera is developing the next generation of electric vehicles.
The 10 Largest Solar Panel Companies in the World, and What They Do – With the solar industry exploding in the 21st century, learn the companies powering the future of green energy.
The 6 Best Solar-Powered Battery Packs You Can Buy Today – Discover amazing solar battery packs that can recharge even while disconnected.