How Do Solar Panels Work for Your Home?

Overview:

• Solar panels contain cells of semiconductive material, usually silicon
• When subject to sunlight, an electric charge is created due to the photoelectric effect (more below)
• The solar energy feeds into your system’s solar inverter(s)
• The inverter(s) changes the energy to a usable state, matching the frequency of the utility grid

Below, we’ll break down how solar panels work in more detail. 

How does the photovoltaic effect work for solar?

For solar panels, the photovoltaic effect occurs when photons from the sun’s rays hit the semi conductive material (typically silicon) in the cell of the solar module. The photons activate electrons, causing them to free themselves from the semiconductive material.

Due to the structure of a solar panel, the free electrons move in a single direction through the junction of the panel. This movement creates an electrical current that is then sent to an inverter to be harnessed by your home.

Photo Credit: Ponor (creative commons image).

Photons hit the solar panel causing electrons to be freed during the photovoltaic effect. 

How is solar energy used in your home?

The power generated by your solar system is direct current (DC). Your inverter then captures the DC energy and transitions (or ‘inverts’) it to alternating current (AC) in order to make it in a usable state for your home. 

Most home solar systems are “grid-tied” meaning that you’re interconnected to the utility’s electric grid and the electrical system of the home. The connection is typically through the main electric service panel, although some systems are tied into “sub” or distribution panels. 

During daylight hours, the AC electricity output by the solar inverter(s) is backfed onto the main service panel, and that electricity is used up by any loads or demand (lights, AC, fans, machinery, anything), thereby making the solar panels work and produce power for your home.

What types of material are used in solar panels?

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

• Monocrystalline cells tend to appear darker in color, often black or dark grey
• Polycrystalline cells often appear a dark blue when exposed to light
• You may be able to see small crystalline pieces of silicon melded together to form the wafer in polycrystalline cells
• Monocrystalline cells generate higher panel efficiency
• Monocrystalline cells 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.

Alternatively, a lower-cost, slightly less efficient, polycrystalline panel may do the job just as well if you have ample roof space on your home.  Be sure to ask what type of cell (“mono or poly”) your home solar system design contains – this distinction may affect the aesthetics and economics of your project.

How does sun exposure affect solar panel efficiency?

It is 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.

More sun exposure means more photons hit the solar panel, thereby freeing more electrons and creating a stronger current, meaning more power for your home. 

How are solar panels mounted?

Solar panels can be mounted to just about any home’s roof when the appropriate hardware and methods are used by the installer. Panels can also be mounted on ground (often called a “ground-mount”). Due to the need for trenching and a more comprehensive racking structure, ground-mount installations tend to be more expensive than a roof-mounted installation.