Solar power is incredible, but how does solar energy work? In this brief guide, we explain everything you need to know about it.
The best power sources on our planet are renewable. The sun only provides a set amount of power at any given time, and we can only harness a tiny fraction of it, but the fact that we get more every day means it’s functionally limitless. If you’re asking “how does solar energy work?”, you’re in the right place – here’s how the system functions from beginning to end.
The Source Of Power: Photons
The answer to how does solar energy work lies in its source, the sun. The sun is the most significant source of power in our solar system. It continually releases small bursts of energy known as photons – incredibly tiny particles made of waves of electromagnetic radiation.
Many people describe photons as a packet of energy, and the name is apt. Each photon holds its energy in a moving electrical field, and when moving, they travel without losing speed or energy unless they’re affected by an outside source.
However, even though they’re energy, we don’t directly convert photons to usable power. Instead, we rely on a trick of photons to generate electricity.
The Photovoltaic Effect
When photons (light) strike something, they can knock existing electrons loose from a surface. Think of this as a game of billiards – each photon is like a tiny ball that knocks other little balls around when they collide. The probability of hitting something is quite low, but with enough attempts, it happens often enough to matter.
When the electron is knocked free, other laws of physics take over, and it begins to move around the area. As they progress, they generate an electromotive force, and we siphon that away for power. Meanwhile, the electrons themselves continue to move around and settle back into position on the original side of their object. Since the electrons move back into place, we don’t “run out.”
Each solar panel uses solar cells, and when asking “How does Solar Energy work?” we can’t overstate the importance of solar cells. A solar cell is a small panel built with a positive and negative layer that create an electrical field. They’re a lot like tiny batteries. By putting lots of solar cells together, we can get a useful amount of electricity.
Creating The Solar Panel
Solar cells are essential, but they’re only one part of the process. Most solar panels use crystalline silicon for their cells (and these are recognizable by their black or blue grid pattern). Each square is a single solar cell, and they’re linked together to generate more power.
Busbars connect the cells. In short, busbars are thin ribbons (usually made of copper or aluminum) that help to create higher voltages. When there are more busbars, more electrons can move through the panel, increasing its overall power and efficiency.
Monocrystalline panels are a popular choice because of their high efficiency. We make these by artificially growing crystals that we cut into the proper shape. These crystals are even and have no grain marks, which gives them an extremely high level of efficiency.
The main alternative for most people is Polycrystalline, which is created by pouring molten silicon into a cast to get the correct shape. This creates imperfect crystals and a distinctive grainy appearance. Polycrystalline is not as efficient as monocrystalline, but it is cheaper.
At the moment, the monocrystalline is a better investment for most people.
The solar cells are a vital part of the solar panel, but they’re not the only one. Most panels are protected in the front by a type of quartz glass. Don’t let the name fool you – they’re much harder to break than windows are.
Solar panels are expected to last for at least 25 years in practically any weather conditions, from giant hail to tree limbs flung by high-speed winds. If they break under the first impact, they’re probably not going to last long enough to provide a good return on their investment. As such, every reputable manufacturer makes the fronts as tough as possible.
From here, things start to vary a little more. Most solar panels use a polymer backing to provide as much electrical insulation. The backing tends to be either white or black, chosen mostly for aesthetic reasons. These are surrounded by a sturdy aluminum frame, which allows each moving and mounting for each solar panel.
That’s the traditional setup, but some solar panels use a bifacial design where they expose solar cells on each side. Other boards use a frameless configuration where the solar cells are sandwiched between two panels of glass with little or no metal.
Ultimately, the best design choice is whatever works for the installation. Some large arrays link hundreds of panels together, and exposing too much metal to that much light could cause problems. Different isn’t necessarily bad in solar panel design, but you should always know why designers make a specific choice.
The Next Step: Inverters
Solar panels have a significant problem: They only generate Direct Current (DC) electricity. In this setup, the electrons flow in one direction. However, the energy grid of the United States uses Alternating Current (AC) electricity, where the electrons move back and forth.
The two types of electricity are not compatible. The main grid uses AC because it’s much easier to transmit power over long distances without losing too much of it. DC is more of a short-range option.
The solution to this is the power inverter, which turns Direct Current energy into Alternating Current energy. As with all systems, this isn’t perfect – we lose about 5% of the electricity generated, which means you need a few more solar cells to produce the same amount of energy you’d otherwise have.
That said, most areas are willing to accept a single-digit loss of efficiency if it means ensuring the power is compatible with everything else we use. Aside from converting electricity, inverters also provide fault protection, tracking, and other helpful information.
We install most inverters in one of two ways. The more common choice in the past is a central inverter, which manages an entire solar system. However, centralized inverters have known problems, including allowing a problem with one panel (such as being in the shade) to drag down the performance of the entire system.
The increasingly-popular alternative is the use of micro-inverters, which are optimized for each panel. By linking these together, it’s possible to ensure that each solar panel functions at peak efficiency.
How Does Solar Energy Work: Using The Power
Up to this point, “how does solar energy work” is all about making solar energy – but it doesn’t matter how much electricity we generate until we start using it.
Most solar arrays feed electricity directly into a home or business. It may be the only source of power a home has while active, or it may link a little more closely to the overall electrical grid. Other systems are less direct about how they work.
A popular alternative is installing a large battery somewhere in the home. When we generate electricity, the battery stores it and everything else in the house can pull power from that. As with the inverter, there’s a loss of power when we store energy this way – but it also means that you can use solar energy whenever you want, not just when the sun is out.
Most solar systems produce more energy during peak hours than people need – especially if you’re not home during the day. As a result, it’s possible to feed extra power into the electrical grid so someone else can use it. When this happens, you get a credit for the energy provided. This can either reduce your regular bill or be drawn from to get power later on (such as during the night).
A process known as net metering is used to record how much energy you provide and how much you draw from the grid. Net metering is central to the spread and use of solar energy, and it helps the grid function at maximum efficiency.
In other words, you don’t have to use solar energy to get the benefits from it. Unless you’re building a house and want to be completely off the grid (in which case a battery setup is vital), cooperating and using net metering is usually a more effective way of lowering your bills.
Where Is Solar Energy Going Next?
Aside from how does solar energy work, that’s a great question! Researchers are working on new ways to make and use solar energy. Ideas range from photosynthesis (the most effective way to turn sunlight into energy), floating solar panel farms (highly predictable light, no meaningful limits on size), and even collecting the energy in space before beaming it back down to Earth.
On a more terrestrial level, some researchers are working on ‘trees’ that can generate power from light and wind, which could significantly improve their efficiency in some areas.
Regardless of method, all efforts for solar energy are trying to make it more efficient. When efficiency goes up, relative costs go down, and that makes it easier for the technology to spread. Over the next few decades, solar energy is expected to grow enough to generate about 20% of the electricity we use – and reduce our reliance on fossil fuels in the process.
When you got here, you asked “How does solar energy work?” You now know the answer.