Frequently Asked Questions

Solar Basics

  1. What is solar electricity?
  2. Basic PV terminology
  3. What is a watt?
  4. What is a kilowatt-hour?
  5. How does PV work?

System Design

  1. What size system should I install on my home or business?
  2. How do I find out my past annual consumption (kWh)?
  3. How much do photovoltaic systems cost?
  4. How efficient are photovoltaic modules?
  5. Where should I put my panels?
  6. What are the components of my system?
  7. Do solar panels and inverters come with a warranty?
  8. Where can I find a list of solar installers in the San Diego area?
  9. What is the CSI Tool Lending Library?


  1. What are the current state and federal incentives?
  2. What is the difference between an expected performance-based buydown (EPBB) and a performance-based incentive (PBI)?
  3. How do I apply for these incentives?

Net Metering

  1. What is net metering?
  2. Does San Diego Gas & Electric offer net metering?
  3. What are the benefits of net metering?
  4. How do I sign up for net metering?



Solar Basics

  1. What is Solar Electricity?

    Photovoltaic (PV): photo = light, voltaic = produces voltage

    Photovoltaic (PV) systems, also referred to as solar electric systems, convert sunlight directly into usable electricity in your home or business using semiconductor technology. Sunlight strikes the PV cells and cause the electrons to flow, creating an electrical current (photovoltaic effect).

  2. Basic PV Terminology
    • DC: Direct current (produced by solar panels)
    • AC: Alternating current (used in the homes, business and industry)
    • Efficiency: Measure of how much of the sunlight is converted to electricity (%)
    • Capacity: Total amount of power that a system produces
    • Watt: Basic unit of power
    • Kilowatt: A unit of electrical power equal to 1,000 watts (most common measurement)
    • Kilowatt-Hour: Basic unit of energy. The use of 1,000 watts of electricity for one full hour (basic unit of electrical usage billing)
  1. What is a watt?

    The basic unit of power. Solar panels and lightbulbs are rated in watts.

  2. What is a kilowatt-hour?

    The basic unit of energy: Energy = Power x Time.

    Example: If ten 100-watt lightbulbs are left on for one hour, the energy consumed is 1 kWh (100 w x 10 = 1 kWh).

  1. How Does PV Work?

    Photovoltaic (PV) systems convert light directly into electricity using semiconductor technology.

  1. Individual photovoltaic (PV) cells are connected to panels. Solar panels convert sunlight into direct current (DC) electricity.
  2. An inverter converts direct current (DC) into alternating current (AC) for electricity in the home.
  3. The utility meter records the net amount of energy generated through the PV system. When you’re creating more electricity than you’re using, your meter will spin backward and the excess electricity is sent to the electric grid. This helps to offset the cost of your electricity usage at night or on cloudy days when your system is not producing electricity.

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System Design

  1. What size system should I install on my home or business?

    Every site is different, and the needs of the system owner vary. System size depends on several factors, including how much electricity (kWh) is consumed on site and the orientation and tilt of the system, as well as available space and capital.

    The first step is determine the annual kWh consumption of the home or business. Once calculated, you can pinpoint avenues on how to reduce your energy consumption by implementing energy-efficient improvements, a necessary first step before installing solar. If you reduce your kilowatt-hour consumption, you may be able to install a smaller PV system, in turn allowing for lower up-front costs and a shorter payback period.

    Sizing your solar electric system appropriately is the key to a faster return on investment. The production of the proposed system should be parallel with the consumption on site and not oversized. According to AB 920, San Diego Gas & Electric is required to purchase excess generation, however, the excess generation is purchased at a reduced rate of about $0.04/kWh. (See the Net Metering Section for more details.)

    Remember that you do not have to offset 100% of the consumption of your home or business. Offsetting any portion can be beneficial and a good way to get started with solar. A rule of thumb is to divide your annual consumption (kWh) by 1700 kWh/year (1kW of solar will generate about 1,700 kWh/year). This will give you an approximate system size to base your design on.

    For example: The Smith residence consumes 6,000 kWh/year.
    (6,000 kWh/1,700kWh = 3.5 kW)

    This means that a 3.5 kW solar electric system would offset 100% of their energy consumption of the Smith residence.

    Also, be sure to use our Electric Rate Analyzer Tool to determine how different system sizes will affect your electric bills.

    Under California's net metering law, eligible systems cannot be larger than 1 megawatt of peak power output.

    There is no minimum system size to be eligible for net metering.

    Always check with a licensed installer or contractor to determine the true optimal size of your system for the portion of your consumption that you wish to offset with solar.

  2. How do I find out my past annual consumption (kWh)?

    You can visit SDG&E's Energy Waves website, which will provide you with up to 17 months of your past consumption. You can also simply add up the kWh consumption from your last 12 months of electric bills.

    Once you know your annual kWh consumption you can move forward to making your home more energy efficient, reducing before producing. You can then move forward with sizing and designing your system.

  3. How much do photovoltaic systems cost?

The price of a photovoltaic system is determined based on a number of factors, including system components and configuration, the difficulty of installation and available incentives. To be clear, the costs mentioned here are the installed cost. This means the final cost (before rebates) to the consumer for the equipment and labor to install and connect a photovoltaic system.

The cost of solar has decreased by 48% since 1998.* The current average installed cost ($)/watt for a residential solar electric system in California is between $4-$7/watt, while larger commercial and institutional systems typically cost $3-$7/watt. Generally speaking, the larger the system, the lower the cost. In addition, the larger the number of systems, for example a new home construction development of 200 homes, the lower the cost.

Contact a local contractor/installer to receive a quote.

  1. How efficient are photovoltaic modules?

Photovoltaic module efficiencies range from 5%, for some thin-film technologies, up to 19% for single crystalline (rigid) technologies. These percentages refer to the conversion efficiency, or the percentage of sunlight that is converted directly into electricity. Conversion efficiency is a critical issue when space is limited. The more efficient the module is, the less space that is needed to produce the desired amount of electricity.

  1. Where should I put my panels?

PV panels can be installed on your roof or as a ground mount. Speak with your contractor about where on your property will yield the highest production. In the SDG&E region, the ideal direction to have your panels face is south or west. If you live close to the coastline, a western-facing system may benefit you more than a south-facing system, due to the presence of the marine layer in the morning and stronger sun in the afternoon hours.

  1. What are the components of my system?

    Here is a list of components that may be included in your PV system. For more information about your PV system components, please view the webinar "Understanding Your PV System."

    • Solar Panels/Modules – The tools to collect the sun’s power and produce direct current (DC) power.
    • Inverter – Converts DC power into alternating current (AC) power. AC power is what we use in our homes and businesses. Central and micro are the two types of Inverters.
    • Service/Utility Meter – This meter is a bidirectional smart meter that can keep track of any excess kWh production that you may send back to the grid.
    • Kilowatt-hour Meter – This meter keeps track of the kilowatt-hours your system has produced since the system was turned on. Note: Not all systems have a kilowatt-hour meter installed.
    • AC Disconnect - This is a device that the utility can use to turn off your PV system in an emergency or service situation. Note: Not all systems have an AC disconnect.
    • Conduit – Conduit is what the wiring for your PV system is housed in. Conduit is usually rigid piping such as EMT (electrical metallic tubing), flexible aluminum or PVC (polyvinyl chloride) piping.
  1. Do solar panels and inverters come with a warranty?

    Your solar panels will come with a 25-year production warranty. Your inverter will come with a 10-year warranty. Most inverter manufacturers offer a supplementary 10-year extended warranty for an additional cost. Please contact the inverter manufacturer for more information.

    To participate in the California Solar Initiative, a contractor must provide a minimum 10-year warranty on workmanship. This is to protect against defects and undue degradation of electrical generation output. For self-installed systems, the warranty need not cover the labor costs associated with removing or replacing major components. These repairs would be completed at the self-installer’s expense. For more information, see Section 2.4 of the CSI Handbook.

  1. Where can I find a list of solar installers in the San Diego area?

    To find a list of active solar contractors in your area, visit California Solar Statistics. This site lets you search for installers by ZIP code, city, county, utility or statewide. The list you receive will provide you with the contractor's name, address, phone number, website, number of installs in the chosen area and average price per watt.

  1. What is the CSI Tool Lending Library?

    CSE offers site assessment tools for loan, free of charge. Tools can be checked out for a 10-day period, with available extensions upon request. The Lending Library includes the following tools.

    Solmetric Suneye 210: An integrated shade analysis tool for solar site assessment. It includes a fisheye camera and a dedicated onboard processor to perform digital image processing and analysis to compute shading and solar access percentages. It includes an electronic compass and inclinometer enabled to measure roof pitch and azimuth.

    Solar Pathfinder: A nonelectric shade analysis tool for solar site assessment. It uses a highly polished, transparent, convex plastic dome to give a panoramic view of the entire site. All the trees, buildings or other obstacles to the sun are plainly visible as reflections on the surface of the dome. The sunpath diagram can be seen through the transparent dome at the same time.

    Oakton TempTestr - Infrared Thermometer: Measures the surface temperature of an object. The unit’s optics sense emitted, reflected and transmitted energy, which is collected and focused onto a detector. The unit translates the information into a temperature reading that is displayed on the unit. In units with a laser, the laser is used for aiming purposes only.

    Daystar Solar Meter: Measures global solar power in watts per square meter. Readings are instantaneous.

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  1. What are the current state and federal incentives?

    The CSI residential incentive program has exhausted its funding for the CSE/SDG&E territory, and as of April 11, 2014, at 5:00 p.m., the residential wait list will be closed to new applications. You may view the status of an existing wait list application or review the wait list process.

    Due to limited program funds, all nonresidential applications received on or after February 5, 2015 will be placed on the Wait List. If Program funds become available, Reservation Requests will be reviewed in the order they were received.

    For customers of Southern California Edison (SCE) and Pacific Gas & Electric (PGE), refer to the Trigger Tracker website for available funding. For territories not mentioned above, contact your local utility to inquire about available solar incentives. 

    In addition to the California Solar Initiative rebate you may also be eligible for the 30% federal tax credit. Check with your tax professional.

  1. What is the difference between an expected performance-based buydown (EPBB) and a performance-based incentive (PBI)?

    The CSI Program offers two types of incentives: expected performance-based buydown (EPBB) and performance-based incentive (PBI).

    The EPBB incentive is a one-time, lump-sum incentive payment, based on the expected performance of your solar electric system. The nameplate rating (watts) of the panels is combined with system characteristics such as location, shading and orientation to create a CSI rating in kWs. This CSI rating will determine the incentive amount. Systems under 10 kw are required to receive the EPBB incentive.

    The PBI incentive is a cents-per-kWh payment for the actual production (kWh) from a solar energy system over its initial five years of operation. The payments are dispersed monthly, for a total of 60 payments. System over 30 kW are required to participate in the performance-based incentive program.

  2. How do I apply for these incentives?

    Typically the solar contractor will apply for state incentive on the behalf of the home or business owner. In the event that your solar contractor is unable to apply for you, visit our Commerical Application Page for more information on the application process.

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Net Metering

  1. What is net metering?

    This program is for customers with solar electric or wind generating systems. If your system produces more energy than you use, you can earn bill credits for the excess power you put back into the SDG&E electric grid. You can later use that credit to cover the power you may need from SDG&E at times when your own self-generation doesn't fully meet your needs.

  1. Does San Diego Gas & Electric offer net metering?

    Yes. Under California law, all public and private utilities, including irrigation districts and cooperatives, that operated prior to January 1, 1998, must offer net metering. New electric service providers, who began selling electricity after January 1, 1998, may choose to offer net metering.

  1. What are the benefits of Net Metering?

    You can receive full retail value for the production of your system
    Net metering allows you to use the power that your solar electric system produced and offset the consumption in your own home. SDG&E acts as a bank to store your production, then allowing you access that power to offset your own consumption. This is equivalent to getting full retail value for the power your system produced.

    You can receive wholesale value for the excess production of your system
    If you solar electric system produces more than kWh you consumed annually, SDG&E will purchase excess energy from you, at a wholesale rate. Currently, the buyback rate is ~$0.04/kWh. (See the Net Metering Section for more details.)

    You can store power on the utility grid
    Due to the fact that you get credit for your excess power generation, it is not necessary to install a battery storage system. However, some may still decide to opt in for a battery backup for storage. Through net metering, SDG&E acts as your “battery bank,” storing your power free of charge.

    The interconnection process is streamlined
    Customers participating in net metering can use the simplified interconnection online application. This is particularly beneficial to businesses because it simplifies a previously complex process.

  1. How do I sign up for net metering?

    It's simple. As soon as you decide to install a PV system, visit the net metering application page to get started. Often, the installer will apply for the business or homeowner. Once all installations and inspections are completed, the homeowner and installer will receive the Permission To Operate (PTO) letter. Only at this point are you permitted to turn on your system. SDG&E Net Metering: 858-636-5585 or

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