Frequently Asked Questions

In case of a discrepancy between the answers to these questions and the Rule 21 tariff, the tariff overrides the answers.

General Question About Electric Rule 21

Electric Rule 21 is a tariff (or set of regulations) that describes the interconnection, operation and metering requirements for generators to be connected to a utility’s electric system. The California Public Utilities Commission (CPUC) has jurisdiction over the Electric Rule 21 tariff. The Rule 21 tariff and the related CPUC-approved interconnection agreements are generally the same for each of California’s large investor-owned utilities (PG&E, San Diego Gas &Electric Company and Southern California Edison) and are available on the utilities' websites. View PG&E's version of the Rule 21 tariff (PDF).

Rule 21 applies to customers who:

  • Generate power only for their own or "over-the-fence" use and do not export power to the electric grid.
  • Generate power for their own use and for export to the electric grid for credit on their PG&E bills.
  • Operate as qualifying facilities (QFs), as defined by the Federal Energy Regulatory Commission’s (FERC's) Public Utility Regulatory Policy Act (PURPA), that sell all of their energy that is exported to the grid to PG&E through a PURPA Power Purchase Agreement

The State of California provides incentives for the development of generators fueled by renewable energy sources. Your facility must use a renewable generation technology to qualify for Net Energy Metering (NEM). Renewable energy sources are defined in the latest version of the California Energy Commission’s (CEC’s) Renewables Portfolio Standard (RPS) Eligibility Guidebook and Overall Program Guidebook, as well as in PG&E's NEM tariff, as:

  • Biomass

  • Solar thermal

  • Photovoltaic

  • Wind

  • Geothermal

  • Fuel cells using renewable fuels

  • Small hydroelectric (but a small hydroelectric generation facility is not eligible if it will cause an adverse impact on in-stream beneficial uses or cause a change in the volume or timing of stream flow)

  • Digester gas

  • Municipal solid waste conversion

  • Landfill gas

  • Ocean wave

  • Ocean thermal

  • Tidal current
Please see the CEC’s webpage for the most current information.

To qualify for the RES-BCT program, a generating facility must also meet the standards for an eligible renewable energy source under RPS guidelines.

Interconnection is the electrical connection, using wires and protection devices, that allows your electric generator and the utility system to operate in parallel. Regardless of whether you export energy, your generator still operates while connected with the electrical grid. As a result, it must  interconnect with the grid in a manner that ensures:  :

  • Safety—All electric generating systems are potentially dangerous if they are not operated properly. If your system connects to PG&E's electrical grid, PG&E must review and approve it to ensure the safety of the entire grid and to protect you, our personnel and other customers. Even if you don't intend to export energy to the grid, part of PG&E's responsibility is to ensure that the energy you generate does not flow back to the grid and create unsafe conditions.
  • Reliability—PG&E must be able to meet our customers' expectation that power is always available when needed. If a fault or trip occurs on a customer's generation system, we must be able to isolate the problem so other customers can continue to enjoy reliable power.
  • Compliance with government regulations—The Federal Government and State of California require that all generators operating in parallel with the grid have an interconnection agreement with PG&E.

Applying for Interconnection Under Rule 21

  • If you select a Net Energy Metering rate schedule, RES-BCT, or a non-export interconnection, you must apply under Rule 21.
  • If you select a PURPA Power Purchase Agreement under which you sell all your exports to the grid to PG&E, you can either Rule 21 or the Wholesale Distribution Tariff (WDT). The procedures are very similar, with similar applications, fee structures and technical requirements.
  • If you select a non-PURPA PPA, under which you sell your exports to the grid to a third party, Rule 21 is not an option, and you must apply under the WDT.
A Public Utility Regulatory Policy Act (PURPA) Power Purchase Agreement (PPA) is a contract with PG&E to sell the power your system exports for a CPUC-approved, avoided-cost amount. To export energy to the grid for sale under a Rule 21 interconnection, you must enter into a PURPA PPA. An example of a PURPA PPA is the Feed-in-Tariff provided for in Assembly Bill (AB) 1613.
Application Fee
Electronic applications are not complete until we receive your processing fee and study deposit  (unless you are exempt).  Please see Table E-1 under E.2.c of Rule 21 for more details.

Site Plan
Show generator location with respect to building, transformer, main switchboard, utility disconnect switch and other pertinent electrical equipment.

Single Line Drawing
Must include PG&E revenue meter (net generation meter for NEM) and utility disconnect switch with manufacturer and model number if required.

Site Control
Documentation reasonably demonstrating site exclusivity as stated in Electric Rule 21 Section C.

Proposed Relay Settings
Required if the generator is not certified or an external relay is used.

Protection Operating Description
Required if the generator is not certified or an external relay is used.

Because PG&E is fully committed to keeping customer account information  confidential, we will not share your information with your contractor or other representative without an Authorization to Receive Customer Information or Act on a Customer's Behalf form providing your written authorization. (This information is built in to the September 2012 Standard NEM Application form.) You can use this form to authorize your contractor to complete most of the paperwork needed to apply for interconnection to the PG&E electric grid. If you plan to fill out the application materials yourself and you do not require PG&E to share your account information with your contractor, you do not need to submit this form.

The California Energy Commission may also require you to fill out an authorization form if you are applying for a rebate from them so they can access your account information.

PG&E requires that customers submit their applications online except for Standard NEM and Virtual NEM at this time.

For Standard NEM and Virtual NEM only, you may submit your application package to Pacific Gas and Electric Company by registered U.S. mail, ATTN: Electric Generation Interconnection, Mail Code N7L, P.O. Box 770000, San Francisco, CA 94177-0001 or via e-mail submissions to

The queue is a list of interconnection applications used to assign responsibility for modifications or upgrades to the electric grid during the study phase. The queue also keeps track of the modifications and upgrades identified in a study phase but not yet implemented.

For all interconnection projects under Rule 21 except Net Energy Metering, PG&E assigns a queue position and posts it monthly to our website, as required by Rule 21 Section E.5.d. This queue is integrated with PG&E’s Wholesale Distribution Tariff interconnection requests.

In accordance with Rule 21, PG&E will conduct some or all of the following reviews to determine the interconnection requirements for a generation project. Generally, we will complete all steps in the interconnection process, including reviews and studies, within the timeframes outlined in Rule 21.

  • Application Review: PG&E usually will acknowledge your application and review it for completeness within 10 business days of its receipt. The application must be complete before PG&E can move on to the initial review.
  • Initial Review: As required by Rule 21 Section F.2, this review should be completed within15 business days of PG&E's acceptance of the completed application. The review will determine if the generation facility qualifies for a simplified interconnection or if a supplemental review is required.
  • Supplemental Review: This review, if required, should be completed within 20 business days of authorization to begin the review and our receipt of the $2,500 study fee, if required. The review will determine if the generation facility can be interconnected or if a Detailed Interconnection Study is required.
  • Detailed Interconnection Study: The Detailed Interconnection Study process is for interconnection requests that are electrically independent from other proposed interconnection requests and fail to qualify for the Fast Track Process. The Detailed Interconnection Study process actually includes two studies listed below. These studies will determine if the generation facility can be interconnected and identify requirements to facilitate the interconnection. This process requires Financial Security Postings.
  • System Impact Study: This should be completed within 60 business days after authorization to begin the study and PG&E's receipt of the study deposit, if required. The study deposit is $10,000 for projects less than 5 MW and $50,000 plus $1000 per MW for all other projects, up to $250,000.
  • Facilities Study: This should be completed within 60 business days of authorization to begin the study and PG&E's receipt of study deposit, if required.  The study deposit is $15,000 for projects less than 5 MW. For all other projects, the deposit submitted for the System Impact Study will be applied toward the cost of the Facilities Study.
  • Transmission Cluster Study: This process, if required because the project fails the Transmission Electrical Independence Test, requires the applicant to reapply under PG&E’s Wholesale Distribution Tariff Cluster Study Process to proceed with the interconnection. If the applicant does not take this step, the project is withdrawn from the Rule 21 queue.

The Interconnection Application Process

The timeline for completing the interconnection process varies. Project energy needs, location and impact on the PG&E electrical system all affect the amount of time your interconnection process can take. This chart includes some typical project timelines from application receipt to commercial operation (generator online).  Your actual timeline may vary.

Fast Track Process 3-5 months

Detailed Interconnection Study 12 months

Delays in an interconnection project can be related to location, energy needs, electric system infrastructure and size of generator. In addition, some of the more common causes for delays include:

  • Missing or illegible field entries (for example, meter number) on the Request for Interconnection. Please complete all fields using a computer or print legibly.
  • Mixed pages from old and new versions of the Request for interconnection. If your application/agreement requires updates, we recommend an entirely new submission using the current version.
  • Incomplete application/agreement package. Use the list of required documents in each interconnection request form to make sure you have assembled all the items you need to submit a complete application. Click here to find the correct form.
  • A change in proposed project design.
  • Failure to perform a Commissioning Test (PDF) before your Pre-Parallel Inspection is scheduled.
  • Use of non-certified and non-approved generation equipment (including protective relays, disconnect switches, transformers and generators).

Inspections and Tests

Depending on the specific characteristics of your generation project, a number of inspections and other requests may be required to complete your interconnection under Rule 21. PG&E inspects generating facilities to ensure they meet Rule 21 standards for safety. For certain rate schedules (such as E19 or agricultural), PG&E may also perform a field investigation/pre-inspection to review the project for safety and access issues and determine the type of net meter to install. A system with components approved by the California Energy Commission (CEC) will typically meet the standards. However, additional requirements may apply to your project depending on the ability of PG&E’s grid to accommodate the energy your generator may export to the grid.
A commissioning test is an evaluation performed by a professional engineer, factory-certified technician or licensed electrician who is qualified to test equipment to verify its protective settings, functionality and batteries. A commissioning test must be performed before your pre-parallel inspection. Please see Rule 21 (PDF) for more information on commissioning tests.
A pre-parallel inspection is the functional testing, witnessed by PG&E personnel, of your generation facility and its protective equipment. PG&E may require this inspection of your facility prior to paralleling it with the electrical system.
Once you notify PG&E that your generator is ready for a pre-parallel inspection, it can take up to 10 days to schedule an inspection of a certified generator with no external relays and up to 30 days for all other generators, depending on PG&E's resource availability.

Please be sure all the following steps are completed before you schedule your pre-parallel inspection with PG&E:

  • Execute all required agreements
  • Arrange for PG&E to install the net energy meter if required
  • Provide a copy of the final signed building permit and inspection for the generation facility
  • Complete all electric work required by PG&E
  • Ensure that PG&E has completed installation of (PG&E-owned) gas service and meter if required
  • Complete your commissioning test and certification

If your generator is non-certified or certified with external relays, you must also submit the following information to PG&E a minimum of 15 business days prior to the inspection (electronic submissions are preferred):

Your Interconnection Agreement requires you to notify PG&E of changes to your generating system. Our engineers will need to review your new equipment to assure the continued safety and reliability of the grid. If you have any questions about a modified system that has already been approved, please call our Business Customer Center at 1-800-468-4743.

Net Energy Metering and Biling

Net Energy Metering (NEM) is a rate schedule that allows customers with an eligible electric generator to offset the cost of their electric usage with energy they export to the grid. With NEM, the customer pays only for the net amount of energy used from the utility. A specially programmed “net meter” (a meter that registers the flow of electricity in both directions) is installed to measure the difference between the electricity the customer purchases and exports to the grid within given time intervals. NEM customers are allowed to "net" their total annual energy exports to the grid against their annual usage. In some cases, when customers consume less energy than what they generate, the excess energy exported to the grid over this annual period is also purchased by PG&E at our avoided cost.

 Net Energy Metering in California is available for solar, wind, biomass, biogas, hydro, geothermal and other renewable energy systems up to 1 MW. PG&E's NEM programs are: Standard NEM, Expanded NEM, Other Renewable NEM, NEMV, NEMVMASH, NEM Multiple Tariff and NEM Fuel Cell. The methods of applying credit for exported energy vary with the program.

Costs to participate in Net Energy Metering depend on the scope, size and complexity of your generation project. You may have to pay  to replace your existing meter or to add utility equipment to interconnect your generator.
After your generating facility receives "permission to operate," PG&E will install a "net meter" on your property to measure the net energy--the difference between the amount of electricity supplied to you by PG&E and the amount of electricity you export to the grid over the course of a month. We will enroll your account in the NEM program on a 12-month billing cycle, read your meter monthly and calculate the net energy recorded in kilowatt hours (kWh). If you export more electricity than you draw from PG&E in a given billing cycle, the amount will be considered a surplus. If you receive more electricity from PG&E than you export, the amount will be considered a charge. The rate at which your charge or surplus will be calculated is based on the electric rate schedule you request in your Interconnection Agreement with PG&E, which is the same schedule your account would be eligible for without your generating system.

If you select a time-of-use or seasonal electric rate schedule, your account may reflect a surplus even if  you are not a net generator because, on some electric rate schedules, the rate per kWh is higher during certain times of day or year (e.g., summer season). If you generate more than you consume during these periods, you may be credited at a higher rate than the rate you're charged if you consume more than you generate.

Your charges or surpluses and applicable meter reads are detailed in your monthly NEM statement. While this statement is not a bill, it allows you to track your accumulating charges and surpluses. You'll continue to receive your regular PG&E bill during each billing cycle for other minimum, meter, customer, demand-based and gas charges. After 12 billing cycles, your charges and surpluses will reconciled to result in your annual "true-up bill."
With the enactment of Assembly Bill 920 (AB 920) California utilities, including PG&E, have been authorized to offer special compensation — called Net Surplus Compensation (NSC) — to NEM customers whose renewable energy systems produce more electricity than they receive from the utility over a 12-month period—also called the “true-up period.” NSC is based on a rolling 12-month average of spot market prices and may fluctuate on a monthly basis. If you qualify for an NSC payment, it will be added to your PG&E bill as a credit. If a negative balance exists on your PG&E bill during your true-up month when this credit is applied, you may request a check. PG&E automatically enrolls NEM customers in this program.
PG&E needs reasonable access to read and maintain your meter, which we own, to ensure accurate billing. We also may require 24x7 access to the disconnect switch near the meter so our workers may disconnect the system in the event of an emergency or to correct unsafe operating conditions.
There are a variety of financial incentives and resources for self-generation.
Virtual Net Energy Metering (VNEM) allows the owner of a multi-tenant or multi-metered property to install a single qualifying generating system to cover the electrical requirements of both common and tenant areas connected at the same service delivery point. In this situation, the electricity does not flow directly to any tenant meter; rather, it feeds directly back onto the grid. PG&E then allocates the kilowatt hours from the energy produced by the qualifying generating system to both the building owner’s and the tenants' individual utility accounts based on a pre-arranged allocation agreement. The intent of VNEM is to help tenants receive direct benefits from the building's electrical generating system, rather than all of the benefits going to the building owner.  To qualify, a generating system must be a “Renewable Electric Generating Facility” as defined in PG&E Electric Schedule NEMV (PDF).

Community Choice Aggregation program

Yes, if you were eligible for NEM with PG&E as your energy supplier, you will still be eligible for NEM if you receive service from a CCA. PG&E will continue to calculate your non-generation charges and credits as we do today, and your CCA will determine its own generation-related charges and credits. Contact your CCA to discuss its NEM program. If your CCA is Marin Energy Authority, please visit

PG&E performs a true-up at the time you change your energy supply service from PG&E to your CCA. PG&E will continue to send out your bill; however:

  • For your generation charges, your bill will include charges or credits calculated by your CCA. Generation charges, shown on your PG&E rate schedule, appear under "Energy Charge." Please contact your CCA to find out how your generation charges are determined.          
  • PG&E will continue to determine the non-generation NEM credits and charges that appear on your bill.
If you switch from one energy supply provider to another, all your credits and charges need to be reconciled before you start your new service. If you are resuming full bundled PG&E services, we will perform a true-up of our non-generation charges and credits when you switch.  Depending on the terms and conditions of the CCA’s NEM program, the CCA may perform a similar true-up of its generation-related charges and credits.
Yes, all retail electric customers in PG&E's service area who install a solar photovoltaic (PV) generator are eligible for California Solar Initiative (CSI) incentives. This includes customers who receive their electricity from a CCA. To be eligible for these incentives you must meet the CSI program guidelines.

Yes, you remain eligible for NEM if you are receiving your electric supply from a CCA.  You will need to contact the CCA for details about its NEM program. Your CCA will determine its own NEM-related charges and credits for the generation portion of your bill.  PG&E will continue to be your point of contact for the interconnection of your solar or wind generator with the electric grid and will calculate NEM-related charges and credits for the non-generation portion of your bill.

 PG&E provides permission to operate your generation system under NEM regardless of who supplies your energy. To apply for NEM, please complete and submit to PG&E the documents listed on the Standard NEM website under “How do I apply?”. PG&E will review your completed application and, if approved, install your bi-directional meter. You may operate your system following receipt of your Permission to Operate letter. 

If your solar or wind generator is larger than 30 kilowatts (kW), please follow the instructions on applying for Expanded NEM.

You own any RECs for the power you generate and use at your own site. PG&E owns any RECs for the power we purchase under the PPA.

No, you will not get a rebate from the California Solar Initiative, but you may qualify for a rebate under the Self-Generation Incentive Program. California Public Utilities Commission rules state that customers who sell their excess power to PG&E under a PPA cannot also get a rebate through the California Solar Initiative.

No. The California Public Utilities Commission has decided that customers who sell their power using a Feed-in Tariff must sell all their exports; they cannot split exports between NEM and a PPA.

We will meter both your usage and your exports to the grid.

If your existing meter can separately meter usage and exports, then you will not have to pay for two meters. However, you may have to pay a reprogramming charge so your meter will appropriately collect the information needed. If your existing meter cannot separately meter usage and exports, you will need to pay for the installation of a new meter.

Yes. If you plan to interconnect a generator in the downtown areas of San Francisco or Oakland, you should contact PG&E’s Electric Generation Interconnection department at while you are still in the planning stages, before you purchase equipment and begin installation. If your planned generator site is in an area served by a secondary network, you may qualify for a non-export option but you will not be able to export power to the grid.

PG&E generally has two types of electrical distribution systems: secondary and radial networks. Secondary networks are designed to meet the higher reliability needs and limited space commonly found in urban areas. The criteria PG&E uses to install secondary networks are a function of the density of the load, economics and other related factors. In PG&E's territory, only the downtown areas of San Francisco and Oakland are served by secondary networks.

In a secondary network, electricity is delivered through a complex, integrated system of transformers and underground cables that operate in parallel. Power can flow in either direction on the lower-voltage service delivery lines, commonly called secondary distribution lines. The loss of a single line or transformer in a secondary network does not cause an interruption of power, unlike in radial systems where there is only one line for power to flow through, starting at the distribution substation and terminating at the customer’s service entrance or meter. If a radial line experiences an outage, service is interrupted until repairs are completed.

In secondary networks, devices called “network protectors” prevent power from “back-feeding” from one transformer through another. Network protectors open (that is, break the circuit) quickly when they detect back-feeding. Any power exported by a generator into this system is detected as back-feeding by the network protectors. Since most network protectors are not designed or tested to operate as switching or isolation devices for operating electric generators, PG&E can't allow installation of net energy generators within areas served by secondary networks.

Miscellaneous Questions

Blackout coverage depends on how your system is configured. The contractor who installs your system should be able to answer this question. Keep in mind that your system design must not allow your generator to export power to the grid during a blackout—this could cause serious injury. For more information on system design for backup power, go to the California Energy Commission's Guide to Photovoltaic (PV) System Design and Installation.
Once your generating system has been approved by PG&E, it does not go entirely off the grid. Your system will be "interconnected," which means that it may export power to the grid, but when your system is off or does not fully meet your energy needs, PG&E will still provide you with power. For safety, PG&E linemen may have to isolate your system from the grid if they need to work on the lines near your site. Please cooperate to ensure the safety of our employees.
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