The Basics of Solar Energy: How Photovoltaic Systems Work

If you want to learn more about solar energy and photovoltaic systems, you’ve come to the right place. Below, we’ll explain the basics of solar energy and how photovoltaic systems work, from the types of solar cells available to the designs of mounting structures and more.

Two Branches of Solar Power

There are two basic types of systems when it comes to solar energy: photovoltaic (PV) and solar-thermal power. While each form has specific applications, most people commonly use PV solar power systems for residential and commercial solar power. Concentrating solar-thermal power is reserved for large-scale requirements, as this system uses hundreds or thousands of mirrors to collect the sun’s energy into a high-temperature fluid in a receiver, like a massive solar harvest farm.

On the other hand, PV systems use solar cells and panels, which many of us are familiar with. In this system, the solar panels absorb energy from sunlight, creating an electrical charge that moves to an internal electrical field in the cells where electricity can then flow.

Now that you have a brief overview of the system types, continue reading to further explore the basics of solar energy and how photovoltaic systems work.

Photovoltaic Systems and How They Work

Simply put, a PV solar power system converts sunlight into electrical energy. But how? It all starts with the solar cell. A single PV device is known as a solar cell, which produces around one to two watts of power.

The solar cell is composed of semiconductor materials of various types that are sandwiched between protective materials like glass or plastic to guard the inner components from natural elements. When the cell’s semiconductor is exposed to sunlight, the light’s energy transfers to the electrons in the material and the extra energy from those electrons flows through the material as an electrical current.

Solar Cells

While solar cells are the foundation of a PV system, they’re not very big and they only produce one or two watts of power per cell, per hour. In order to maximize solar power harvesting, the cells are chained together. These chains of solar cells are called solar panels or modules and can vary in size due to the shapes of the cells, ranging in configurations of 32 to 96 solar cells.

A standard residential solar module is roughly 65 x 39 inches. The average residential solar panel on today’s market is rated to produce roughly 250 watts per hour. Alternatively, commercial PV solar panels are typically bigger than residential panels since they need to generate more energy.

Types of Solar Cell Semiconductors

As previously mentioned, solar cells contain semiconductor materials; when the semiconductor is exposed to light, it absorbs that light’s energy and transfers it to electrons. The efficiency of a PV cell, or the amount of electrical power it can harvest and produce compared to the energy of the light, depends on the light’s characteristics and the semiconductor materials.

Silicon

Silicon is the most common semiconductor material for solar cells, so if you only learn about one type of cell, this is the one to know. More than 90 percent of solar module cells contain silicon.

One of the reasons silicon is so popular is that it’s the second most abundant material in the world, behind oxygen. Additionally, silicon is relatively cheap, meaning there’s no concern with overconsumption. Crystalline silicon cells are comprised of atoms connected via a crystal lattice. The lattice structure is incredibly efficient at converting light into electricity, and silicon cells provide high efficiency, low expenditure, and can last 25 years or longer.

Thin-Film

A thin-film solar cell has two or more layers of PV material on a protective surface like glass, plastic, or metal. There are two main types of thin-film semiconductors: cadmium telluride (CdTe) and copper indium gallium selenide (CIGS).

CdTe is the second-most common material for PV cells, but it’s in a distant second place. CdTe is cheaper to produce than CIGS, but it is less efficient than CIGS cells.

Perovskite

A perovskite cell is another type of thin-film cell—although it’s not as common as CdTe and CIGS—and it is named after its unique crystal structure. A perovskite solar cell consists of layers of material printed, coated, or otherwise deposited onto a substrate.

A perovskite cell is relatively easy to assemble and is nearly as efficient as silicon. In the past decade, perovskite cells have become significantly more efficient than when they were first produced. Currently, the only drawback of perovskite solar cells is they’re not very durable. Still, if that issue is rectified, they could become nearly as common as silicon solar cells.

Design Basics for PV Solar Power Systems

Solar cells aren’t the only parts of a PV system—there are also mounting structures, inverters, and storage batteries.

Mounting Structures

As one could guess, the mounting structure of a PV system supports the solar panels and protects them from natural elements like wind, rain, and hail to prevent damage and corrosion. Mounting structures include a tilt option to face the PV array at an angle that maximizes solar exposure based on the local latitude, orientation of the modules, and load requirements for the system.

The most common mounting structure is rack mounting, which is easy to construct and relatively inexpensive. However, building-integrated PV is becoming more common. This is when cells are integrated directly into the building, such as on the roof, awning, facade, windows, or shade canopy.

Inverters

A PV system’s inverters convert the direct current electricity from the modules into the alternating current used for local electricity transmission. Some PV systems have one inverter for all the modules, or microinverters operating within each module.

Both inverter types have their advantages, but microinverters are gaining popularity as they allow for independent operation and are less prone to shading.

Batteries

Lastly, all of that wattage from the modules has to go somewhere—that’s where the batteries come in. After sunlight is absorbed and converted into alternating current, the energy moves to the storage batteries.

The storage batteries allow homeowners and commercial building managers to store any leftover electricity so there will still be power available at night or during days with minimal sunlight.

The final piece of a PV solar power system is the solar placards and labels necessary for compliant and safe identification. Whether you need a solar label for your residential or commercial PV system, Get Solar Labels can help! Browse our website to find the products you need, or contact our helpful staff today to learn more.