Net Metering Overview
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Net metering is associated with customers who generate at least a portion of the electricity they use through means of solar PV, wind, biomass from animal waste, fuel cell, or other qualifying renewable energy generating systems.
Customers that generate their own electricity, and are connected to the utility's distribution grid, offset electricity that would otherwise be purchased from the utility.
There may be times when the customer's system generates more electricity than the home needs. In these cases, a credit is issued to the customer's account for the extra power that can be used during the following month(s) until the annual true-up. In other words, the customer will only pay for the energy that PSE provides.
Benefits of net metering:
- Creates a reduction in electricity bills.
- Net metering ensures that the customer's system is connected to the utility's grid, so even during cloudy or windless days, there is always a dependable source of electricity.
How net metering works
A net meter is capable of measuring both the electricity supplied by the utility as well as any excess supplied by the customer's system back to the grid.
One of the primary benefits of net metering is that when a customer's home requires less electricity, like when everyone is at work or school, the system may still produce electricity. When the system is connected to the grid, that electricity is being put back into the grid. The difference between what the home uses from PSE versus what they system generates is the "net" in net metering.
Detailed requirements can be found in the Electric Schedule 150 Tariff and the Electric Schedule 150 Attachment B agreement, Electric Schedule 150 Attachment EZ agreement, or can be requested from a PSE Energy Advisor.
Information for system installers:
All customer generation system applications and schematics should be approved in writing by PSE before a system is installed. Learn More. »
The WAC rules for interconnection and PSE interconnection agreement states:
(iv) Disconnect switch. Unless the Washington state department of Labor and Industries requires a visible, lockable AC disconnect switch, an electrical company shall not require a visible, lockable AC disconnect switch for interconnection customers installing and operating an inverter-based UL 1741 certified system interconnected through a self-contained socket-based meter of 320 amps or less.
Tier 1 systems are typically self-contained meter bases only and are 200A or 320A services only. There is no change for CT rated services and they still require a disconnect switch.
To satisfy the requirements of WAC 296-45-335, "De-energizing Lines and Equipment for Employee Protection," PSE must have the ability to disconnect a generator from PSE's system. If a customer's production system meets all of the following:
- Output is 25 kW or less
- Single phase service
- Self-contained meter
Then PSE will use an optional disconnect switch, net meter, or transformer as the point of disconnect. If the customer's production system meets any of the following:
- Output is greater than 25 kW
- Three phase service
- CT metered
Then the customer shall install a lockable, visible break disconnect switch. The lockable AC disconnect switch shall be adjacent to the service meter and accessible to PSE personnel at all times.
For a complete set of definitions please see: http://apps.leg.wa.gov/wac/default.aspx?cite=480-108-020.
Disconnect switch definition
A single blade-type, visible break and lockable disconnect.
Disconnect switch location
When a production system requires a disconnect switch, the following criteria shall be applied to determine the location of the disconnect switch:
- For 240V and 120/208V self-contained and CT rated production meters, the AC disconnect shall be on the line side of the production meter (between the production meter and the inverter).
- In the case of 480V self-contained production meters, the disconnect shall be on the load side of the production meter (between the production meter and the customer panel).
- In the case of 480V CT rated production meters, the AC disconnect shall be on the line side of the production meter (between the inverter and production meters).
- For customers that have no load between the PSE transformer and inverter (typically community solar or power purchase customers), only one bi-direction meter is necessary to monitor production credits and inverter load. The disconnect shall be on the load side of the generation/service meter (between the meter and the inverters).
- Exception: For 480V self-contained meters, the disconnect shall be located on the line side of the service meter.
- When more than one production meter is required for the customer production system, the disconnect location shall be determined by PSE Meter Engineering.
Processing applications and ordering meters:
PSE is dedicated to customer service for its Net Metering program for both the customer/generator and the consultant/installer community. Currently when a meter set is ordered, it involves the coordination of different groups within PSE. The PSE Meter Department alone will visit the customer site while the Relay Technicians will stand ready for unusual situations where they are needed.
PSE will order meters once the electric inspection has been completed.It will be the responsibility of the customer or customer representative/installer to inform PSE that the system has passed inspection and is ready for meters. Language for the Certificate of Completion can be found in the net metering application. From PSE's side, we are committed to having the meter installed within 10 business days.
Please contact us early and often. A good system diagram will be vital to making this process run smoothly. Again, a couple key points:
- Please continue to submit the applications and system diagrams before installing any equipment.
- PSE will order meters once the electrical inspection has successfully been completed.
- Net Metered systems should remain off until the Net and Production Meters have been installed.
- The customer or customer representative should be home when PSE installs meters.
Variances and production meter locations:
The Production Meter (or meters) must be located "adjacent" to the Service Meter (Net Meter). "Adjacent" is defined as within 6-ft (6-ft maximum, 10-in minimum clearance center-to-center for all sockets) and along the same wall (not around the corner). The only allowed exception is when the service meter is on a separate structure from where the generation system is located. In this case the Production Meter can be mounted on the same structure as the generation instead of adjacent to the service meter, providing the location meets all requirements such as access and clearance, etc. It must also connect into a subpanel in the detached structure. If there is no subpanel, the meters should be co-located.
A typical example would be a solar system on a barn where the barn is served off a branch circuit from the house main panel. In this case the production meter could be located on the barn rather than adjacent to the service meter on the house.
Production meter placement must still meet all other applicable rules for accessibility.
A second typical example would be a house with solar panels that is served through a meter loop (remote pedestal) at the end of the driveway. In this case the production meter could be located on the house rather than in a second pedestal adjacent to the service pedestal.
These two exceptions will cover the vast majority of requests for a production meter to be placed away from a service meter. Other than these two non-standard placement scenarios, customers can request a variance on meter placement, but due to safety of system operations, it is rare that they are granted. To request a variance, contact email@example.com, and the request will be reviewed by PSE Meter Engineering and PSE Electric Standards.
If a solar array is on a detached structure, like a barn, and it is on a separate service, it will be up to the customer or customer representative to inform PSE that meter aggregation is being requested.
Meter socket requirements
- All 480V meter sockets shall use a safety socket
- All non-residential meters shall use a manual bypass socket
- Installers may not tap inside a meter socket
Number of production meters
Customer systems shall utilize the fewest number of production meters as possible. If a customer chooses to expand on an existing system, the customer must use the existing production meter unless the production credits are being paid at different rates.
For detailed information please see PSE's electric service handbooks for Single-Family Residential or Commercial/Industrial and Multifamily, Permanent and Temporary Service.
We are committed to a 10 day meter installation window, we are eliminating the need to request a meter location variance in most cases, we are committed to improving the process for ourselves, the installer community and most importantly the customer.
Typical generating systems include:
- The mode of generation, such as solar PV, wind generators, small-scale hydro, and biomass.
- An inverter, which converts the DC (direct current) energy produced to AC (alternating current).
- A disconnection device, which ensures system safety for PSE employees and customers.
The type of device depends on the total output capacity of the system.
Net metering resources
Here are a few of many websites and guides that offer useful renewable energy information:
Glossary of net metering terms
The following terms may be helpful as you go about estimating and constructing your electrical generating system.
PSE customers who have enrolled in PSE's net metering program and have signed an interconnection agreement with PSE, becoming potential suppliers (generators) of electricity to PSE.
Inverters convert the DC (Direct Current) voltage that the generator creates to AC (Alternating Current) at either 120 volts or 240 volts. The inverter sends the AC voltage into the home's circuit breaker panel, where it is distributed to the home or electricity grid through the net meter.
Hydroelectric generation or "micro hydro"
An electrical generating system using water as the means to turn an electrical generator. These systems sometimes use a waterwheel, similar to those used since medieval times. They can have a vast range of sizes and operating characteristics.
The process of calculating the electricity used by a Customer-Generator versus the amount of electricity generated by a qualifying generating system owned/operated by the customer-generator.
Solar systems using PhotoVoltaic (PV) modules. These modules are typically made out of silicon and can be found in many commonly-used products, including calculators. The modules are assembled into arrays or panels that are capable of generating anywhere from 100 to over 200 watts of electricity per array. Typical solar PV system capacities range from one kilowatt (or 1,000 watts) to over 10 kilowatts.
To learn more terms, visit: