As environmental consciousness and the use of alternative energy sources continues to grow, solar power has become increasingly prevalent. And thanks to technological advances over the last 20 years, solar is one of the most versatile and flexible power options available. In fact, the International Energy Agency reports that solar is currently the world’s fastest-growing source of power.
There are currently over 2.7 million individual solar installations in the United States, and the solar market has grown every year over the last decade. From a small array supplementing your reliance on the grid to a community-based system powering several homes, solar can integrate seamlessly into your life.
Solar power offers freedom from unpredictable energy pricing and allows you to engineer a system that works for your property and budget. It’s also the cleanest and most abundant renewable energy source on the planet. And new payment structures — including tax incentives and financing opportunities — make solar power more affordable than ever.
But how does solar energy work? How does energy from the sun travel from your solar panels into your home to power your daily life? Let’s take a closer look at the logistics of solar energy to gain a better understanding of what solar power looks like in action.
How Does Solar Energy Work?
Solar energy starts with sunlight, which is composed of tiny, weightless particles known as photons. Each photon carries a small amount of electromagnetic force, which can be converted into usable thermal or electrical energy. This transformation happens through an electronic process occurring naturally in materials called semiconductors. Solar energy frees the electrons in semiconductors and sends them through an electrical circuit to power your devices or put electricity on the grid.
How Do Solar Panels Work?
Solar panels are powered by photovoltaic (PV) cells, which convert the photons in sunlight into usable energy. PV cells play a significant role in determining the effectiveness and efficiency of your solar energy system.
Each PV cell is made from thin layers of silicon or a similar semiconductor material. The top layer is typically coated (also known as “seeded” or “doped”) with phosphorus to create a negative charge. On the other hand, the bottom layer of each cell is seeded with boron to create a positive charge.
The area between these two layers is known as a silicon junction, which is a kind of electrical circuit. The sides of each PV cell contain a series of conductive plates that are often made from silver. However, new solar panels typically use materials that are more affordable and easier to source to reduce costs.
When sunlight hits the top of a PV cell, its photons strike and ionize the semiconductor material on the solar panel. This knocks loose a group of outer electrons, which break free of their atomic bonds, enter the silicon junction, and generate a charge. This electrical charge is carried away by conductive materials and converted into usable electricity. A typical residential solar energy system converts 16-22% of the sun’s PV energy into usable power.
Understanding the History of PV Technology
The photovoltaic effect was first observed in 1839 by a French physicist named Edmund Becquerel. However, it wasn’t until Bell Labs developed the first workable solar cell in 1954 that scientists began to understand how the PV effect works.
President Jimmy Carter signed the Solar Photovoltaic Energy Research, Development and Demonstration Act in 1978, ushering in a period of rapid technological advancement. But early adoption of solar panels was slow due to the low efficiency of photovoltaic technology. Generating enough solar power to run a property required large arrays, limiting its usefulness to rural, commercial, and off-grid properties.
In 1985, the University of South Wales became the first organization to break the 20% efficiency barrier. In 1994, the National Renewable Energy Laboratory produced a solar cell capable of exceeding 30% conversion efficiency. Since then, PV cells have continued to get smaller, more affordable, and more suitable for widespread use.
How Long Do Solar Panels Last?
While most solar panels are warranted for 20 years, their lifespan is actually much longer. There are no moving parts to burn out, and no materials are lost from the solar cells or modules over time. Best of all, decreases in power output are less than 1% per year.
Other Components of a Solar Installation
Photovoltaic cells are only one part of your solar energy system. Each solar array also requires the equipment below.
Solar panels produce the most energy in direct sunlight, so how and where they’re mounted directly affects their efficiency. Mounting systems can be fixed in place or mechanically repositioned throughout the day to maximize exposure.
Most homeowners and businesses mount their solar array on the roof of their house or office. However, some companies and larger properties incorporate photovoltaic cells into their parking canopies, eaves, and other structural components.
Solar panels produce direct current (DC) electricity, rather than the alternating current (AC) power required by most homes and businesses. Inverters play the crucial role of turning the DC power from your solar panels into the AC power your home or business needs. Inverters come in a wide range of sizes and specifications and choosing the right one warrants careful consideration of your energy requirements.
Along with converting DC electricity into AC power, inverters help solar installers and owners monitor how a system is performing. Inverters also provide diagnostic information for outage and management crews, allowing them to identify and repair malfunctions. And if you have solar power with battery backup, your inverter is solely responsible for battery management.
Solar Array Disconnects
The solar array disconnect is an important safety feature that disconnects your system during maintenance or repairs. Most photovoltaic systems have two safety disconnects:
- A PV disconnect (also known as an array DC disconnect) that interrupts the DC current between battery modules before it reaches the inverter.
- An AC disconnect that separates the inverter from the grid and is typically mounted between the inverter and the utility meter. The AC disconnect can be a service panel breaker or a standalone switch and is sized based on your inverter’s output current.
Grid-Tied vs. Standalone Systems
There are two different types of solar energy systems: grid-tied and standalone. We’ll take a more detailed look at each system below.
The majority of home and small business solar energy systems are connected to the power grid. This ensures a reliable source of energy if your system is under producing and also permits smaller, more affordable installations. And in some areas, grid connection allows you to generate income by selling excess power back to your utility provider, known as net metering.
Grid-tied solar energy systems can be configured to automatically switch between utility and solar power. Most customers install a power meter to see in real-time how much usable energy their system is generating and how much is coming from the grid.
Standalone systems are an ideal option for customers who live in remote areas or want to be truly energy independent. Nearly all standalone systems include a set of deep cycle batteries and a charge controller. These batteries store excess energy for use overnight or during overcast periods when your system isn’t working at full efficiency. The charge controller automates the process and ensures adequate power is coming to and from the battery modules at all times.
It’s important to know that standalone solar energy systems don’t qualify for as many rebates and tax incentives as grid-tied systems. They also don’t provide the option of generating additional revenue by selling excess energy back to the grid. As a result, it takes longer to recoup your initial investment in a solar energy system.
How Much Do Solar Panels Cost?
The overall cost of your solar energy system depends on several variables, including:
- System size
- System type (roof- vs. ground-mount, micro-inverters, monitoring, etc.)
- Any special engineering or design required
In most cases, the cost of a solar power system is similar to paying 6-10 years of electricity expenses upfront. Prices vary greatly based on your system size and any state or federal financial incentives you qualify for.