Solar technology has evolved and been adopted by more than 2 million homes across the country since 1954, when scientists at Bell Telephone discovered that silicon-an element found in sand-created an electric charge when exposed to sunlight. Solar panel systems are now a very appealing option for homes and businesses as a clean, affordable energy source.
The fundamentals of solar panel systems We can now harness the energy of an infinite source of power—the sun—thanks to the development of solar panels. Solar panel systems operate in the following manner:
• During the day, solar cells in your solar panels absorb sunlight energy;
• Circuits within the cells collect that energy and convert it to direct current (DC) energy;
• The DC electricity is then passed through an inverter to convert it to usable alternating current (AC) electricity that comes out of your wall outlets;
• All of this means you can use that electricity in your home, store it in a solar battery, or send it back to the grid.
We’ll go over solar panel systems and the equipment you’ll need to generate power from the sun in the sections below. Already know how solar equipment works? Great! Check out the following articles in our Solar 101 section, or go to the next section to learn about the advantages of solar.
What exactly is a solar panel?
A solar panel is a device that collects and converts sunlight into usable electricity. Solar panels are typically composed of silicon-based solar cells, wiring, a metal frame, and a glass cover. A standard solar panel is four feet wide and six feet tall.
What are the components of a solar panel system?
Solar panel installations are very simple systems. Any solar panel system has only four main components and no moving parts, making it very easy to install and maintain. A solar panel system is made up of four parts:
- Photovoltaic solar panels—used to convert solar energy into electricity.
- Inverters—convert DC electricity to alternating current electricity
- Racking and mounting systems—for attaching your solar panels to your roof (or to the ground, depending upon your installation type)
- Performance monitoring systems: These systems track and monitor the output and health of your solar panels and inverters.
Solar Panels
Solar panels are made up of a series of silicon solar cells held together by a metal frame and covered by a sheet of glass, with wiring and circuitry in and behind the cells to collect the flow of electrical current out of the solar cells. Each solar panel, also known as a solar module, is typically 4 feet by 6 feet in size and weighs about 30 pounds.
Despite the fact that there are no moving parts, the “active” component of a solar panel is in the silicon cells themselves: when sunlight strikes the silicon solar cells, electrons are activated and begin to flow through the cell. This flow of electrons is captured by wires in the cells and combined with the output of other cells in a solar panel. Check out our article on solar panels and solar cells for a more in-depth look at how they work.
Solar cells are typically available in 60 or 72 cell configurations. However, many companies are experimenting with new ways to increase the efficiency of solar cells in converting sunlight into electricity current, so you’ll now see many “half-cut” solar panels, in which each cell is cut in half so that the solar module has double the number of cells (i.e., 120 or 144).
All panels are not created equal.
There are several criteria to consider when selecting the best solar panels for your home and budget, including product quality, durability, and long-term performance. The EnergySage Buyer’s Guide for solar has more information on how to evaluate solar panels.
Inverters
Your solar panels’ cells collect the sun’s energy and convert it to direct current (DC) electricity. However, alternating current is used in the majority of homes and businesses (AC). Inverters convert the direct current (DC) electricity generated by your panels into usable alternating current (AC). String (or centralized) inverters and microinverters are the two basic types of solar inverters. String inverters can also be outfitted with power optimizers in order to function similarly to a microinverter system.
String inverter (or centralized inverter): Your entire array of solar panels is connected to your electrical panel by a single inverter. String inverters are frequently the most affordable inverter option, and they are a very durable technology that has historically been the most commonly installed inverter type. Multiple strings of panels can be connected to each inverter; however, if the electricity production from one of the panels in a string drops (as can happen due to shading), the performance of the entire string may suffer temporarily.
Microinverters: If you choose microinverters, one is (usually) installed at each solar panel, allowing each panel to produce the most energy. Microinverters will minimize performance issues if some of your panels are shaded at different times of day or if they are not all installed facing the same direction. Microinverters are typically more expensive than string inverters.
Power optimizers: Power optimizers are a cross between micro-inverter and string inverter systems. Power optimizers, like microinverters, are installed at each panel. Instead of converting the DC electricity from the solar panels to AC electricity, the optimizers “condition” it before sending it to a centralized inverter. They, like microinverters, perform well when one or more panels are shaded or when panels are installed in opposite directions. Power optimizer systems are more expensive than string inverter systems but less expensive than microinverter systems.
Systems racking and mounting
Solar racking and mounting systems are the components that secure your solar panels to your roof or the ground.
Solar panels should face south and be installed at an angle of 30 to 45 degrees to perform optimally (depending on how far you are from the equator). Panels facing east or west and with a pitch angle of five degrees or greater will still function properly, but will produce 10 to 20% less electricity than those installed under ideal conditions.
Most residential solar systems are “lie-flat,” which means the pitch of your solar panels parallels the pitch of your roof. However, in some cases, you can use racking to tilt or position your panels at the best angle for capturing the sun’s rays.
Fixed mounts, in which the panels remain stationary, and tracking mounts, which allow panels to “follow” the sun as it moves across the sky during the day (single-axis track mounts) and as the seasons change (dual-axis track mounts). Tracker mounts are only appropriate for ground-mounted solar panels.
Systems for measuring performance
Performance monitoring systems provide detailed information about your solar panel system’s performance. A monitoring system allows you to measure and track the amount of electricity produced by your system on an hourly basis.
The most popular inverters in the residential market all include production monitoring apps that allow you to track the output of your panels. In some cases, the app will also monitor your consumption to help you track your overall savings from your solar panel system. Please keep in mind that this additional consumption monitoring may come at an additional cost.
Monitoring your solar panel system can assist you in identifying any performance issues, allowing you to maximize the electricity production—and financial returns!—of your solar panel system.
Monitoring systems are classified into two types:
• On-site monitoring: The monitoring device is physically installed on your property and records the amount of electricity generated.
• Remote monitoring: Your solar PV system sends performance data to a monitoring service, which you can access online or through a mobile device.
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