Roof top solar is powered by sunlight. When the sun is shining the PV cells convert the sunlight into electricity, and inverters transform this energy from DC power into AC power so it can power everything in your home. Want to learn more? Here is info on the process and the equipment used.
a. How Solar Works
Individual photovoltaic (PV) cells are connected to panels. These solar panels convert sunlight into direct current (DC) electricity. An Inverter converts direct current (DC) into alternating current (AC) for electricity in the home.
b. PV Cells
Photovoltaic (PV) cells, or solar cells, take advantage of the photoelectric effect to produce electricity. PV cells are the building blocks of all PV systems because they are the devices that convert sunlight to electricity. When light shines on a PV cell, it may be reflected, absorbed, or pass right through. But only the absorbed light generates electricity. The energy of the absorbed light is transferred to electrons in the atoms of the PV cell semiconductor material.
Grid tied Inverters – are connected to the electric utility distribution system. The connected solar system allows you to power your home or small business with renewable energy when the sun is shining. Any excess electricity you produce is fed back into the utility distribution system grid. When the solar system is not running electricity from the utility (grid) supplies your needs. Having the utility as your energy back up source eliminates the needs to purchase costly energy storage device, such as batteries.
Go Solar California
The Go Solar California website provides California consumers a "one-stop shop" for information on solar programs, rebates, tax credits, and information on installing and interconnecting solar electric and solar thermal systems.
Office of Energy Efficiency & Renewable Energy
US Department of Energy produces information on science-based energy upgrades helping homeowners reduce their energy bills.
Energy Efficiency Homes and Photovoltaic Technology Basics
An educational website funded by the US Department of Energy dedicated to educating homeowners about solar power options.
National Renewable Energy Lab Solar Photovoltaic Technology Basics
NREL is a national laboratory of the US Department of Energy, operated by the Alliance for Sustainable Energy, LLE.
Solar Power for Your Home – A Consumer’s Guide
Solar electric power will continue to grow in importance as part of our nation’s total energy portfolio. Why? Here are some reasons….
Improvements in solar electric production technology include:
Increasing Solar Panel Efficiencies
- Simply put, solar panel efficiency is the percentage of sunlight that can be converted into electricity.
- Solar panels are presently rated at about 24% efficient, up significantly since the early 2000’s.
- The expectation is for efficiencies to keep improving. With higher efficiencies, you’ll be able to generate more electricity in less space as designs improve.
Concentrated Solar Electric
- The amount of energy that can be produced by a solar panel is directly proportional to the amount of available light. Concentrated solar amplifies the sunlight to generate more power.
- Concentrated photovoltaic (CPV) uses lenses to concentrate sunlight onto a small area of photovoltaic material to generate energy.
- CPV is presently used in large utility scale solar installations.
Solar Harnessing Infrared Light:
- 40 percent of light from the sun is in the infrared spectrum and is useless to conventional solar.
- Panels that capture all of the light, including the infrared light, may someday be commercially feasible and available.
- This new technology helps solar panels capture sunlight at all ends of the light spectrum, producing more energy without using concentrators.
Hybrid Solar Panels:
- Companies are developing panels that do double duty – the captured light can be used for electricity production and for hot water heating.
- Hybrid systems contain photovoltaic cells and hot-water generating solar thermal tubes.
Solar Panels That Can Work With Indoor Light:
- Solar electric panels are currently designed to work outside in the sunlight.
- Under development are solar products that can harness indoor light to generate electricity.
- The technology is not very effective now, but may someday be common place.
Transparent Solar Panels:
- Solar panels are generally very dark and not transparent.
- Another technology in development is transparent solar panels of a very thin format to roll over a window to generate electricity.
- These products are presently only able to generate enough for small personal appliances and are not very efficient.
Have you heard of the Solar Rights Act? Or the Solar Shade Act? Yes, there are laws and regulations allowing consumers with rights to install solar if they choose. Here is some helpful information on that subject.
What Are Your Rights to Get Access to the Sun?
- You may have questions about whether your neighbors can block access to your solar panels with shading.
- Additionally, can Covenants, Codes, and Restrictions (CC&Rs) limit your use of solar?
- State laws in California protect homeowner access to the sun for systems, and these laws have been in place for more than 30 years.
- Many homes today are part of planned communities that require a uniform and consistent appearance within the development. The California Solar Rights Act and the Solar Shade Act provide important information for homeowners considering to go solar.
Solar Rights Act (AB3250, 1978)
- The Solar Rights Act was created in 1978 (AB 3250, 1978), and it created a legal framework for solar access.
- The law includes protections to allow consumers access to sunlight (and prevent shading of systems) and limits the ability of homeowner associations and local governments from preventing installation of solar energy systems.
- The Solar Rights Act sought to promote and encourage the widespread use of solar energy and to "protect and facilitate adequate access to the sunlight which is necessary to operate solar energy systems.”
- The Solar Rights Act balances the needs of individual solar energy system owners with other property owners by developing solar access rights.
- The Act limits the ability of CC&Rs, typically enforced by homeowner associations (HOA), and local governments to restrict solar installations. These are the best known and important provisions.
- The Act also creates the legal right to a solar easement for a landowner to obtain adequate access to direct sunlight for a solar energy system.
Solar Shade Act (AB2321, 1978)
- The Solar Shade Act (AB 2321, 1978) provides limited protection to solar energy system owners from shading caused by trees and shrubs on adjacent properties.
- The law seeks to prevent a property owner from allowing trees or shrubs to shade an existing system installed on a neighboring property, provided the shading trees or shrubs were planted after the solar collecting device was installed.
Where Else Can You Get Information About Solar Rights?
There are two helpful reports written by the Energy Policy Initiative of the University of San Diego's School of Law about the Solar Rights Act and the Solar Shade Act:
- Solar Rights Act: A Review of the Statutes and Relevant Cases (December 2014, PDF)
- California's Solar Shade Control Act: A Review of the Statutes and Relevant Cases (March 2010, PDF)
U.S. Department of Energy Report on Private Land Use Restrictions and Solar:
- Bringing Solar Energy to the Planned Community: A Handbook on Rooftop Solar Systems and Private Land Use Restrictions. You can download this report as an Adobe Acrobat PDF file (62 pages, 1.0 MB).