How Do Solar Panels Work? A Guide for Homeowners

How Do Solar Panels Work?

At the heart of solar panels is something called the photovoltaic (PV) effect. At a high level, here’s how it works:

• Inside the panels are special materials called semiconductors. When the sun’s rays hit the solar panel, they transfer their energy to atoms in the semiconductor.
• This solar energy knocks electrons — tiny negative particles of energy — loose from the atoms, setting them in motion. As sunshine keeps striking the solar panel, more and more electrons get knocked free, creating a flow of electricity.
• To make this flow of electricity move in a particular direction, the semiconductor material is treated with special chemicals to create an electric field with a positive and negative side. The loose electrons naturally want to move to the positive side.
• Metal plates on the solar panels collect and channel the freed electrons moving through the semiconductor. The electrons then flow out of the solar panel as direct current (DC) electricity, which a solar inverter then converts to the alternating current (AC) electricity required to power the average home.

Solar Panels

Also known as photovoltaic (PV) panels or modules, solar panels are made of silicon cells covered in glass. We’re only talking about PV technology, not solar thermal systems that absorb sunlight to use in residential heating applications like hot water and swimming pools.

There are two types of PV panels — monocrystalline and polycrystalline. Monocrystalline is more efficient at converting sunlight into electricity, and it’s what we offer our customers at Sunnova.

Individual solar panels are called modules; these are lines of PV cells connected in a series to produce a higher voltage. When modules are wired together in a chain, they form a panel. A group of panels on your roof or ground-mounted in your yard is called an array.

Solar Panel Racking

The solar panel mounting system (also known as racking) is what attaches the panels to your roof. While your racking configuration depends on the type of roof you have, some of the more common profiles include:

• Shingle Roof Mounting. Installing on these roofs generally requires flashing attachments that mechanically fasten the array beneath the shingles.
• Flat-Top Roof Mounting. This type of roof commonly utilizes a ballasted or hybrid mount system to secure the solar panels, and often doesn’t require penetration to install.
• Metal or Corrugated Roof Mounting. This roof type typically requires penetration to fasten the panels. Anchoring options include an “L-foot” bolt, or clamps that fasten to the metal ribs of the roof.

Some installers may even offer solar mounting options that attach directly to your roof, which are usually faster to install and more aesthetically pleasing.

Reputable installers will take great care in sealing the area around your racking equipment to prevent leaks and should also provide you with a warranty that covers leakage.

Utility & Solar Meters

You’re likely familiar with a traditional electric meter, which your utility uses to measure your energy usage for the month.

But when you go solar, your utility may need to either replace your traditional meter or add a second dual-direction meter that measures how much solar power you produce and send back to the grid.

This also helps the utility determine how much to credit you, if a net metering or similar program is offered in your region.

Solar Inverters

The solar inverter is what converts DC electricity from your panels into AC electricity that your home can use. There are three main types of solar inverters:

• String inverter. The oldest and typically most inexpensive option, this type of inverter is installed at ground level. All the solar panels are connected to a string inverter and to each other, meaning if a single panel fails, it will likely cause the other connected panels to underperform.
• Microinverter. Offering the latest technology and ideal for more complex solar installations, microinverters are installed behind each solar panel or integrated into the solar panel directly. This means each panel operates independently, and if one fails, it will only have a minimized impact on the overall system.
• String inverter with DC optimizer. These are a hybrid between microinverters and string inverters. Each panel is connected to a DC optimizer that runs to a string inverter at ground level, allowing each panel to operate independently.