Most people know that solar panels convert sunlight to electricity, but they’re often unclear on how solar panels perform their work. Fortunately, you don’t need to know the intricate inner workings of solar technology to benefit from it. But a little understanding of how solar panels work will help you make an informed purchase if you’re considering a solar system.
Key takeaways
Solar panels use semiconductors to convert sunlight into usable electricity for your home.
The photovoltaic effect is the process by which sunlight is converted into an electric current to power your home.
You can install solar systems that completely offset your home’s energy usage.
When solar panels don’t produce enough energy, your solar system will automatically pull electricity from the power grid.
How does solar power work?
The three primary things to know about solar are the photovoltaic (PV) effect, how solar cells work and how solar panels tie into your home’s circuitry.
The photovoltaic effect
At the most basic level, solar panel technology uses semiconductors to convert sunlight into electricity. The most common semiconductor used in solar panels is silicon. When photons from sunlight hit silicon, they knock electrons off the silicon atoms. Because of the specially treated silicon, the newly freed electrons travel in the same direction, looking for another atom to call home.
Another silicon atom inside the system captures these electrons, creating and harnessing an electric current. This process, known as the photovoltaic effect, is why solar panel systems are referred to as solar photovoltaic systems, or solar PV systems.
Solar cells
Solar panels exploit the PV effect by organizing semiconductors into solar cells. The cells are carefully organized into specific geometric patterns to encourage the freed electrons to flow in the same direction. Getting the electrons to flow in one direction, creating a stable current, is important for creating useful and efficient solar panels.
System integration
Solar panels — usually on a rooftop — produce direct current (DC) power. However, your home requires alternating current (AC) power to run. Converting DC power to AC power is the job of your solar system’s inverters.
Most residential solar systems use microinverters, which convert the electricity from individual panels. In some cases, older systems used inverters that converted the electricity from rows of panels or even the entire system all at once.
Microinverters have shown enough promise and success that they will probably dominate future residential and distributed solar markets, according to Seaver Wang, co-director of the Climate and Energy Team at the Breakthrough Institute. Adding a microinverter to each solar panel instead of using one large inverter for a solar system makes installations easier and more flexible.
Installers and owners also prefer microinverters because if one fails, it will affect only one panel, Wang said. An inverter failure would endanger the health of the entire PV system.
How do solar panels generate electricity for my home?
Understanding the science behind solar panels is great, but how do solar panels work with your electric bill? What happens if they don’t produce enough energy? What if they produce more power than you need or use?
If your solar panels produce at least as much energy as your home uses each month, your electric bill will be zero for that month. This is the goal most people have when they switch to solar energy, and it’s why getting the right size system is essential.
However, even with the proper size, your solar system may produce more energy than you need. This situation happens mainly in the summer when sunlight intensity and availability are at their highest. If your electric company has a net metering policy, you can transfer your excess electricity back to the grid for financial credit. You can then draw from your credits for free or reduced-cost energy when your home produces less energy than it needs, such as at night or during extended cloudy periods.
If your utility provider doesn’t offer net metering, you can store excess energy with a solar battery, allowing you to have available reserve power.
If the opposite happens and your system doesn’t produce enough energy to cover your usage, you’ll draw power from the grid as you would if you didn’t have solar panels. You’ll be responsible for paying for the electricity you use at your utility’s normal rate.
What are the benefits of solar energy?
The primary benefits of going solar are a reduced carbon footprint, lower utility bills and the fact that solar panels require little upkeep. The following sections explore each benefit in more detail.
Green energy
As the world moves away from fossil fuels and toward renewable energy sources, more homeowners are jumping on the green-energy bandwagon. Solar power isn’t the only way to power your home with renewable energy, only the most affordable and accessible.
Alternatives like wind power and geothermal systems often are either not efficient enough to run entire houses or prohibitively expensive to install.
Lower electricity bills
One of the main draws of installing solar panels is the promise of lower electricity bills. If you purchase a solar panel system in cash, your electricity bills will drop immediately. Many people don’t owe money to their utility company after they install solar panels, although how much power you need to draw from the grid depends on your monthly consumption and your system’s size.
Of course, you don’t save money until your electricity savings pay for the upfront cost of your solar panels. Solar installation companies estimate that the average U.S. household takes six to 20 years to break even after buying solar panels. Solar homes in sunny states can expect a payback period between seven and 10 years. After that is when the real savings mount for solar homeowners.
Keep in mind, however, that these estimates assume you pay for the system in full upfront. Taking out a solar loan extends the payback period because of added interest costs.
Low maintenance
Many people mistakenly believe solar panels need a lot of maintenance, but most systems need almost no upkeep during their 20- to 25-year lifetimes. Monitor your system’s performance and bring in a solar technician if you notice sudden underperformance. Otherwise, you probably won’t need to give your panels much attention.
What are the limitations of solar panels?
Solar panels are the best way to transition your home to clean energy, but they have a few downsides.
Environmental impact of solar panel technology
Solar panels are a better alternative to fossil fuels, but producing solar panel technology still impacts the environment. Mining the materials needed to make solar panels hurts the surrounding ecosystem and depletes natural resources.
“Disposal of crystalline silicon solar modules has few risks,” said Wang, mentioning relatively harmless waste and modules that can get recycled. However, environmentally friendlier thin-film solar modules account for less than 3% of all solar panels installed and contain heavy metals. First Solar, the largest manufacturer of thin-film panels, has an extensive recycling plan in place, allowing for the reuse of 90% of solar panel materials.
“Overall, the environmental impacts of solar panels are manageable by shifting to cleaner manufacturers and production techniques and by enforcing good end-of-life recycling and waste management,” Wang said.
Another negative impact of solar panel technology is deforestation and land use by large-scale solar farms. Solar panels require direct sunlight to work at their peak, so installing solar panels and solar farms often involves removing trees.
A lesser direct impact, and an irony, is that the facilities that manufacture the panels run on fossil fuels. So, it’s unclear whether the clean energy produced by solar panels offsets the initial environmental impact of burning the oil used to produce them.
Aesthetics
A less significant drawback to solar panels is that many people find them to be eyesores. Solar panels are bulky and hard to hide, which detracts from a home’s curb appeal. Some homeowners don’t mind the appearance, but many do. Large solar installations also break up otherwise picturesque landscapes and detract value from surrounding land. Homeowners who prefer a sleeker look can opt for solar shingles.
High initial cost
One practical drawback of solar panels is cost. Although the production costs of solar panels have decreased over the last few years, they are still expensive. Up to 80% of homeowners can’t afford to buy a solar system with a full payment upfront.
Luckily, most solar installers allow you to finance a solar system purchase through a loan. You won’t save as much money in the long term if you take out a solar loan, but it’s still a good choice for people who can’t afford to pay in full upfront.
The future of solar panel technology
The future of solar panel technology is bright. Some solar research is dedicated to making better photovoltaic cells. Companies like Maxeon are expanding residential solar panel technology, releasing more efficient panels every few years. More efficiency leads to less consumption of fossil fuels.
Other research areas focus on making solar panels smaller and more flexible to broaden their use. A lot of attention is being given to incorporating solar panel technology into windows for use in cities. Some estimates suggest that solar window technology could pay for itself in about 10 years, which could make major cities self-sustaining in a brief time.