Photovoltaic Basics

Process

1. Sunlight is absorbed by the photovoltaic array creating direct current (DC) electricity. The array is can be mounted to the roof or the ground.
2. The inverter takes the DC output and converts it to alternating current (AC). The AC output is then usable either in the building or elsewhere on the utility grid.
3. Depending on the immediate electricity needs of the home/business, electricity can be used by electrical loads on-site
4. Any excess power can be fed to a battery back-up system (optional), or to
5. The utility grid, in a process called 'net metering'. In this case, the utility grid acts as a bank - the power you deposit can be withdrawn from the grid later on, when your PV system is not producing enough power to meet your household's energy needs (in the winter, for instance).

For additional information on Battery Storage Systems and how they compare with generators, read the Marin County Battery and Generator Fact Sheet.

There are a variety of incentives and financing options available to homeowners who wish to install solar systems. Please visit our Incentives and Financing page for more details on programs and rebates.

Photovoltaic Cell - A device that produces electricity from light. Cells are the building block for modules.

Photovoltaic Module - A number of PV cells connected together, sealed with an encapsulant, and having a standard size and output power; the smallest building block of the power generating part of a PV array.

Photovoltaic Array - A group of photovoltaic panels.

For information on each of the solar technologies shown below, please visit the Energy Savers website.

Stand-Alone PV System

Grid-Tied PV System

Building Integrated Photovoltaics (BIPV)

If you are considering installing a solar electric system on your home or business, there are a couple of questions to ask yourself first:

1. Do I receive a reasonable amount of sunshine throughout the year? Look for areas that are free from shade, not blocked by trees or buildings. A shadow, even that of a small branch, can decrease the amount of power that is generated by your system. The County has tools to help you determine if your site is appropriate for solar.
2. What are my criteria for purchasing a PV system? Your criteria will help determine the size, orientation and placement of your system. This criteria might include:
   • Reduction in energy costs
   • Environmental benefits
   • Back-up power
   • Dependent on initial budget
   • Aesthetics
3. What can I do to increase my household energy efficiency before investing in solar?
4. Are there financial incentives and rebates for installing solar?
5. How do I choose the right contractor?

If you are interested in learning how to answer these questions yourself, many edifying resources are available. Start with reading the following photovoltaic guides, made available through the California Energy Commission.

• Buying a Photovoltaic Solar Electric System: A Consumer's Guide
• A Guide to Photovoltaic System Design and Installation

• Northern California Solar Energy Association
• Rahus Institute
• Solar Living Institute
• Vote Solar

• Education
  • Solar Energy International (SEI)
  • Florida Solar Energy Center (FSEC)
  • American Solar Energy Society (ASES)
  • Interstate Renewable Energy Council (IREC)
• Research
  • National Center for Photovoltaics
  • Sandia
  • DOE Energy Efficiency and Renewable Energy (EERE)
  • DOE National Renewable Energy Laboratory (NREL)
• Trade Associations
  • Solar Energy Industries Association (SEIA)

Renewable Energy Directory

Online comprehensive buyers guide and business directory to more than 17,000 renewable energy businesses and organizations around the world. You can locate renewable energy businesses by geographic location, by product type, by business type and by name, or search for businesses using keywords.

Wind Energy Conversion Systems

In August 2010, the County of Marin adopted an updated Wind Energy Conversion System (WECS) Ordinance. Get more information on the update and additional WECS information here.

Summary of California Energy

The Energy Almanac website provides energy information on generation, demand, consumption, prices and sources for California. Information available by types of fuel, sector and county. From the CA Energy Commission.

Energy Statistics for the United States

The Energy Statistics website provides energy information on prices, sales, demand and consumption for all energy types (including renewables). From the U.S. DOE Energy Information Administration.