Solar 101: The Basics
Solar panels can power an incredible range of applications — from a remote cabin to keeping the lights on in the International Space Station. But we all know solar isn’t just for providing remote power needs.
There are virtually unlimited reasons why people choose to go solar. From energy independence, to reducing energy bills, to climate concerns, there’s really no “wrong” reason to install panels. And as solar panels continue to drop in price, they’ve become a competitive energy option for more and more homes and businesses.
Understanding the basics about solar panels is key to comprehending how they harness the Sun’s energy and how they're changing the world. Here are just a few of our favorite solar installs:
- A civic center in Washington State installed 132 solar panels in 2020 and now saves an estimated $3,700 per year. They’ve also reduced the building’s carbon footprint by nearly 22 tons of greenhouse gas emissions annually.
- Wiley Properties in Concord, New Hampshire installed 258 solar panels on the roof of their storage facility, leading to an $11,000 direct improvement to yearly cash flow and 84 metric tons of annual carbon emissions offset.
- Every single agrivoltaics project.
Here we'll discuss all the basics you need to know about solar, including how solar energy is produced and how solar panels are made. We’ll also explore the ins and outs of a solar photovoltaic (PV) system, how to design a top-notch system, and the essentials of going solar.
What is solar energy?
Solar energy is radiant light and heat emitted from the Sun. It’s harvested in myriad ways, such as photosynthesis in plants and solar heating.
Solar energy for electrical production relies on subatomic particles called photons. These particles start their journey in the center of the Sun, traveling through the various layers before careening into space. A journey from the center of the Sun to the surface can take anywhere between 100,000 to 50 million years to complete.
Once photons escape the Sun, they take a little over 8 minutes to reach Earth, where they collide with solar panels and initiate the photovoltaic effect.
How do solar panels work?
Before we get into more details, let’s look at a high-level rundown of what happens from Sun-to-plug in a photovoltaic system:
☀️ Photovoltaic cells absorb photons from the Sun and convert them to direct current (DC) electricity
☀️ An inverter transforms direct current to alternating current (AC)
☀️ AC travels via wire to a breaker box for distribution throughout the home or building
☀️ Any unused electricity flows back to the utility grid or into solar energy storage
The photovoltaic effect (how solar panels generate electricity)
A solar panel’s secret sauce lies in its ability to convert photons into electrons. In a nutshell, a solar panel converts photons into direct current, which is then converted to alternating current for use in home and business applications.
Solar cells are typically constructed of silicon, a semiconductor capable of producing electricity. When sunlight strikes the panel, photons interact with silicon atoms, releasing electrons in a phenomenon called the photovoltaic effect.
A solar cell is manufactured with a positive and negative silicon sheet sandwiched together. An upper silicon layer is infused with phosphorus for a negative charge, and a boron-infused bottom layer maintains a positive charge. The resulting field funnels electrons towards conductive metal and out of the panel.
Grid connection
Once the photovoltaic process produces a current, the electricity has to flow somewhere. Since the current produced by a solar panel is direct current, it needs to be converted into alternating current before it can be used in most situations. Once converted to AC, energy from solar can be used in multiple ways.
The most common setup is a grid-tied system. A grid-tied system draws a significant portion of its energy needs from solar panels during the day. Depending on the size of the system, more energy may be produced than the site needs, so surplus electricity is sent back to the grid. When the Sun goes down, the consumer draws electricity from the utility.
While grid-tied systems aren’t completely self-sufficient, they’re an effective way to lower energy bills and do good for the environment.
Net energy metering
A major advantage of a grid-tied system is the ability to sell surplus solar energy back to the utility through a process called net energy metering, often referred to as NEM or net metering. When the Sun isn't shining — when it's cloudy, at night, etc. — a solar system may not produce enough energy to meet the customer's demand. The opposite is true for very sunny days: When energy use is low but production is high, panels will generate surplus energy, usually more than enough for a customer’s needs.
Net metering measures electrical flow in both directions: How much energy a system draws from the utility, and how much it exports to the grid. When a solar system is overproducing, the meter actually runs backward, resulting in the utility company rewarding credits for the surplus power. These credits can be used to purchase energy from the utility when a solar system isn’t able to meet demand.
What components make up a solar system?
Solar panels are the most obvious components of a photovoltaic system, but only represent about 30% of the total solar system’s cost. The high-tech shimmer of a solar panel is just the tip of the iceberg that a PV system uses to harness renewable energy from the Sun.
Let’s take a closer look at the important components that make up a solar system.
Solar panels
A typical solar panel consists of silicon cells, a metal frame, wiring elements, and glass. An insulative layer and a protective back sheet protect the panel from excessive heat and humidity.
While the general construction of solar panels is pretty standard, the silicon cells are manufactured in a couple different formats:
- Monocrystalline cells are one solid silicon crystal. Mono cells provide more space for electrons to flow, resulting in a smaller, more efficient panel. The downside is they tend to be more expensive.
- Polycrystalline cells are constructed of many individual shards of silicon melted together. While not as efficient as mono cells, poly cells have a lower price point.
Mono and poly cells serve the same purpose. Aesthetics and budget will help you determine which is right for your next project. Mono panels tend to have a darker, more uniform color, while poly panels are lighter (usually blue-ish). If the site is space-limited, mono panels may be the way to go thanks to their higher efficiency. But if space isn’t an issue or you’re up against a tight budget, poly panels are an excellent choice.
Solar panel manufacturing
Just how are solar panels made? Silicon chunks are shaped into cylindrical ingots, with special attention given to proper atomic orientation. At this stage, boron is added to give the silicon a positive charge. Ingots are then cut into thin wafers the thickness of paper and then treated with an anti-reflective coating to help better absorb sunlight.
Next, conductive metals are added to the surface of each wafer. Phosphorus is diffused across the surface, providing a negative charge to balance the positive charge of the boron and allow a controlled flow of electrons.
At this stage, an individual solar cell is complete. Next, cells are soldered with metal connectors into a matrix. This assembly is sandwiched between a protective back sheet and glass covering and finished off with a junction box and frame.
Inverters
Solar energy comes from the panel as direct current and needs to be converted to alternating current before it can be used in a commercial electrical grid. Thankfully, DC is easily converted to AC with an inverter.
Inverters are classified into 4 broad categories:
- Standalone inverters draw DC energy from batteries charged by solar panels and don’t interact with the grid.
- Grid-tie inverters match electrical current from solar panels to the utility. Grid-tie inverters shut down during power outages.
- Battery backup inverters draw energy from a battery and export surplus energy to the grid. Battery backup inverters are capable of delivering AC energy during a power outage.
- Intelligent hybrid inverters are all-in-one solutions that can be used for grid-tie, stand-alone, or backup applications. Intelligent hybrid inverters are often attached directly to solar arrays and manage solar load, battery storage, and grid interaction.
Racking and mounting system
Racking and mounting hardware does far more than secure panels to a roof or the ground — it provides the correct positioning for maximum exposure to the Sun. Selecting the right mounting configuration and positioning is essential for ensuring maximum output from any system.
Solar racking and mounting systems fall into 3 categories:
- Roof mounting systems. The most common roof mounting systems use rails anchored securely to a roof. Other roof-mounted systems attach panels directly to bolts or screws anchored into the roof, eliminating the use of rails. Ballasted and non-penetrating systems are usually used on flat roofs or roofs that can’t support mounting hardware.
- Ground mount systems. Traditional ground mount systems anchor panels to the ground, which can often be stacked two to four panels high. Two rails generally support each panel, which can be oriented in a portrait or landscape position. These systems are anchored to the ground with steel rods, screws, or ballasts such as concrete blocks.
- Tracking systems. Motorized tracking systems follow the Sun throughout the day, maximizing sunlight exposure. Tracking systems are classified as single axis or dual axis. Single axis systems follow the Sun from east to west in a straight line. Dual axis systems track the Sun in a more circular pattern for improved sunlight exposure.
Solar performance monitoring systems
A performance monitoring system is a dashboard that highlights all of a solar system’s information in one place. Aside from the fuzzy feelings of seeing your meter spin in reverse, a solar performance monitoring system offers valuable insights into your photovoltaic system’s performance.
These systems offer information about energy output and consumption, optimize energy usage, and can inform you about problems in your solar system. Solar monitoring systems work through inverters, usually through monitoring software that serves as a liaison between the inverter and other devices.
Performance monitoring systems gather information as the inverter(s) converts direct current to alternating current and make that information accessible to the homeowner through companion apps and smart home devices.
How are solar systems designed?
Many important factors are considered when designing solar systems. A couple that depend on the homeowner and site are particularly important: available space and energy demand. All the nuts and bolts of solar system design hinge on these two factors, so a thorough understanding of them is essential to a well-planned solar installation.
To get started, a solar designer will calculate the customer's energy needs, usually by analyzing the location’s utility bill. Next, the designer will determine the ideal number of solar panels for the project and the available space to accommodate them. With energy needs and available space determined, a designer can start shopping for components.
Designing a solar system can be complicated. A designer must determine space requirements, potential shade, optimal panel pitch/angle, necessary permits, and more. Software solutions can help estimate solar energy needs and plan the best solar system.
There is software out there that can help ease designers' load. Fore example, Aurora Solar’s design software automatically renders high-quality, accurate designs and materials recommendations — and can do so with just an address and a utility bill. Aurora also provides multiple planning and design tools in one intuitive package, including site design, load profiles, shade analysis, automatic system design, sales proposals, permit templates, and more.
Essentials of going solar
For many folks, going solar sounds nice in theory, but the process seems lengthy, overwhelming, and expensive. That’s why it’s important for solar contractors to simplify the process as much as possible for the homeowners. Here are some tips:
- Understand basic solar panel information: Customers usually ask some fundamental questions about how solar works and how it will work for their property. Contractors should be able to explain it in simple terms.
- Make sure the property is suitable for solar: Solar panels can benefit homeowners in every state, but not all properties have optimal solar conditions. Be aware of obstructing factors that would shade the panels, as well as the recommended size, slope, and shape of the roof for the proposed installation. If the property isn’t great for solar, a contractor should be able offer some suggestions or design alternatives to create better solar conditions.
- Crunch the numbers: Money is a universal language. A solar calculator and solar case study information can show solar customers how much they’ll need to invest in their system and how much going solar will save them yearly and over its lifespan. Solar contractors should also explain financial benefits of going solar, like net metering and solar tax credits.
- Offer financing solutions: The cost savings of going solar aren’t always enough to combat the sticker-shock of the price of a solar system. Customers need plenty of solar financing solutions.
