How Do Solar Panels Work?

Solar panels contain cells of semiconductive material, usually silicon, usually encased in a metallic frame and tempered glass. When subject to sunlight, photovoltaic cells create a flow of electric charge inside the solar panel due to the photoelectric effect. This flow travels in a circuit of wires that connect groups of solar panels, called arrays. The solar panels feed into the inverter system. The inverter is the device that converts direct current (DC) electricity to alternating current (AC) to match the frequency of the utility grid so that it can be used to power your home!

In a grid-tied system, the inverter is “tied in” or interconnected to the electrical system of the house, building, or facility usually in the main electric service panel, although some systems are tied into “sub” or distribution panels, pending certain criteria are met. During daylight hours, the AC electricity output by the solar inverter(s) is backfed onto the main panel, and that electricity is used up by any loads or demand (lights, AC, fans, machinery, anything!).

Common Types of Solar Panels

The most common photovoltaic modules, or solar panels, on the residential solar market contain monocrystalline or polycrystalline (also called multicrystalline) solar cells. Both types of PV cells produce electricity when exposed to sunlight, however there are some differences between the two:

• Aesthetically, monocrystalline cells tend to appear darker in color, often black or dark grey while polycrystalline cells often appear a dark blue when exposed to light, and you may be able to see small crystalline pieces of silicon melded together to form the wafer.
• While monocrystalline cells correlate to higher panel efficiency, they also tend to be more expensive.

There are many panel manufacturers that build panels containing both mono and polycrystalline wafers to form solar cells, capable of harvesting energy from a wider spectrum of light. If space is limited on your roof or project site, a higher-efficiency, monocrystalline panel may be preferred, and could result in a better return on investment (ROI).

On the other hand, it’s possible a lower-cost, slightly less efficient, polycrystalline panel might fit your needs best. Be sure to ask what type of cell (“mono or poly”) your solar system design contains – this distinction may affect the aesthetics and economics of your project.

It’s important that your solar panel array(s) are installed in areas that receive good insolation (sun exposure) throughout the day, free from as much shading from trees or neighboring obstructions as possible. This will ensure your system is as productive as possible, given the site conditions.

Solar Panel Mounting

On a typical home, solar panels can be mounted to just about any roof type when the appropriate hardware and methods are used by installation personnel. Panels can also be mounted on the ground (often called a “ground-mount”). Due to the additional trenching and racking structure, ground-mount installations can be more expensive than a roof-mounted installation.

If you live in an area where net energy metering is allowed, your solar system will feed any net excess solar electricity into the grid, and you’ll be credited against future usage!