How Do Solar Panels Work? – USA TODAY

Solar panels save homeowners money on their energy bills since they’re not using as much — or any — electricity from the power grid. But how do solar panels work? To help explain, we spoke to Will White, a solar application specialist at Fluke Corporation, who distilled all of the technological and scientific information down to a digestible level.

In short, solar panels absorb sunlight and create an electric charge. The electricity comes from positively and negatively charged electrons moving to metal fingers and charging the panels. This electricity powers your home or gets stored in a solar battery for later use. We detail all the essential components of a solar panel system and how they work below.

What are solar panels?

Solar panels use sunlight to produce electricity. Let’s look at the different parts of a solar panel to get a better idea of how the process works.

Photovoltaic panels

Your photovoltaic panels are the most important part of your solar system. Solar panels are made up of photovoltaic cells, or PV cells. These cells comprise a semiconductor that absorbs some of the photons that hit it and reflects others. Semiconductors are important ingredients in modern technology — they’re used in everything from solar panels to personal computers and cell phones.

When a semiconductor in a photovoltaic cell absorbs a photon, a current is induced in the cell. That current can be piped into your home’s electrical system to produce electricity or used to charge a solar battery. 

Inverters

Inverters are similarly crucial to your system’s operation. According to White, “An inverter is one of the most important pieces of equipment in a solar energy system because it is responsible for regulating the flow of electrical power.” The inverter transforms your solar panels’ direct current (DC) power into alternating current (AC) that you can use to power your home.

You want high-quality inverters that convert DC electricity to AC electricity efficiently to maximize the amount of energy you can draw from your solar panels. Microinverters, or inverters connected to only one solar panel, are popular because they work on a panel-by-panel basis. By contrast, older solar panel systems use centralized inverters that service several panels at once, which makes it harder to replace an inverter or panel if it breaks.

I personally have microinverters on my solar array, and I’d recommend those to anyone going solar now.

Centralized inverters and microinverters are usually covered for 25 years by a manufacturer’s warranty. Before signing a contract, make sure your solar warranty covers the inverters for at least 15 years so that they last as long as possible.

Batteries

Not all rooftop solar systems include batteries, but some do. Solar batteries let you store the energy you generate with your panels rather than send it back to the grid, known as net metering. That means instead of getting credits from your utility company, you store your panels’ excess energy and use it for yourself later.

Batteries are expensive, so they’re not worth it for everyone. If you live somewhere with net metering at the rate that you pay for electricity — known as retail-rate net metering — batteries probably aren’t worth it right now. However, more states are moving away from retail-rate net metering to programs that don’t pay you as much for the power your solar panels generate.

If you live in a state with one of these programs, batteries can help you save more money in the long run.

I installed two Tesla Powerwalls with my system in New York, even though we currently have one-to-one net metering here, another name for retail-rate net metering. I didn’t want to risk our net metering policy changing in the future, so I future-proofed my system. Plus, if you get batteries installed alongside your panels, the federal tax credit for installing solar panels applies to them too.

How does sunlight turn into electricity in your home?

Let’s take a high-level view of how solar panels turn sunlight into electricity that you can use to power your home’s lights and appliances.

We can’t capture all of the sun’s energy, but solar panels let us use a tiny fraction of the energy that reaches the Earth. When sunlight hits your solar panels, it excites the atoms in the solar cells, knocking some electrons into the semiconductor’s conduction band — the material of the solar cell and the electrons orbiting it — and creating an electric field. This is called the photovoltaic effect.

The electric field causes electrical charge to move across the cell. A positive charge accumulates on one side of the cell, and a negative charge on the other. Moving electrical charges is what we usually call an electric current.

Electricity flows along wires in the solar array and gets turned into usable electricity by the solar inverters. The usable electricity then flows through your home’s electric panel, supplying power to anything that needs electricity. If your solar panels produce more electricity than your home needs, the excess electricity flows back to your power company or to your batteries.

How does electricity get stored?

You’ll need solar batteries if you want to store the excess electricity your solar panels generate. Your solar battery’s role in your system depends on whether it’s connected to the electric grid.

Grid-connected solar systems

The majority of home solar panel systems are connected to an electric grid. There are three electric grids that vary by location: Eastern Interconnect, Western Interconnect and Texas Interconnect. Grid connection is useful if your panels stop producing energy for any reason since you can start drawing power from the grid as you normally would without any service interruption.

Having a grid connection is also useful if your system produces more energy than your home uses. You can sell excess energy back to your power company to earn credits that can offset your future electricity usage costs.

You can get solar batteries for a grid-connected system, but they’re not essential for a functioning home. When your panels are underproducing, you can draw power from your battery rather than the grid to save money on electricity bills. Solar batteries are also useful as an emergency backup power source during outages.

Off-grid solar systems

As the name suggests, off-grid solar systems don’t connect to the power grid. These are more common in remote locations where there isn’t any grid infrastructure to connect to. With an off-grid system, your home gets all of its electricity from PV panels and can’t rely on the grid when the panels underproduce.

Instead, off-grid systems use solar batteries to store electricity for later use. Without batteries, an off-grid system wouldn’t be able to power your home at night or on cloudy days. It would also have trouble generating enough energy during the limited sunlight of winter, depending on where you live.

How do I get solar power for my home?

The first thing you should do is get quotes from as many local solar installation companies as you can — ideally three or more. The cost of your solar panels and the necessary size of your system both depend on your location. You’ll need a local expert to guide you to the decision that makes the most sense for your home.

Solar panel installers will offer you a quote upon inspecting your home. During your inspection, a technician will explain what size system you need and what equipment works best for homes in your region. They’ll also make sure your roof gets enough sunlight to make solar a worthwhile investment.

The best solar companies will help you make a wise financial decision that offers the best return on your investment. Be wary of any companies that push solar leases. Leases benefit solar companies more than solar customers because you can’t get the tax credit if you lease and won’t own the system after your investment.

You’re much better off financing your panels with a solar loan or purchasing them outright in cash if you can afford to. You stand to save much more money in the long run with a cash purchase than you do with either a loan or a lease.

Recap

Solar panels absorb the sun’s light and create an electric charge. That charge gets used by your home as electricity. The excess electricity either gets stored in your solar batteries or gets sent back to the grid. When you send electricity back to the grid, you can get a credit from your electric company.

When you’re ready to switch to renewable energy, you should take your time and consult with as many local installers as possible. You can start by using the tool below to find some reliable solar companies in your area to request quotes.

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