What does Level 1, standalone solar under 12 kW on the looped radial system require?

No application fee. No insurance is required at or below 100 kW, and Seattle states outright that no interconnection customer is required to carry general liability insurance at that size. Screen result within 15 business days of the application being deemed complete.

What does Level 2, solar 12 kW to 100 kW, any resource to 100 kW, or solar of any size on the network require?

No application fee. Screen result within 20 business days. Resources on the network system must be non exporting and install specific equipment.

What does Level 3, inverter based above 100 kW to 500 kW require?

An application fee applies at this level, set in the underlying policy rather than the handbook. Insurance of $1,000,000 is required above 100 kW up to 2 MW. Net metering no longer applies; the Large Customer Renewable Generation Program does.

Seattle City Light distributed energy resources: tiers, fees and insurance

How the size is measured

the rated capacity of the resource in AC, which for an inverter based resource is the combined rated capacity in AC of the inverters that are part of it. This is the cleanest definition among the large publicly owned utilities, and Seattle applies the same one to both the interconnection level and net metering eligibility. One test, one number.

Size bands and what each one obliges

Level 1, standalone solar under 12 kW on the looped radial system Size 0 to 11.999 kW	No application fee. No insurance is required at or below 100 kW, and Seattle states outright that no interconnection customer is required to carry general liability insurance at that size. Screen result within 15 business days of the application being deemed complete. Safety disconnect switch per Construction Standard 0097.03, shown on the site plan UL 1741 SB and IEEE 1547-2018 certification
Level 2, solar 12 kW to 100 kW, any resource to 100 kW, or solar of any size on the network Size 12 to 100 kW	No application fee. Screen result within 20 business days. Resources on the network system must be non exporting and install specific equipment. Safety disconnect switch Non export scheme if on the network system
Level 3, inverter based above 100 kW to 500 kW Size 100.001 to 500 kW	An application fee applies at this level, set in the underlying policy rather than the handbook. Insurance of $1,000,000 is required above 100 kW up to 2 MW. Net metering no longer applies; the Large Customer Renewable Generation Program does. Application fee per the underlying distribution policy $1,000,000 liability insurance
Level 4, above 500 kW, machine based, or failing supplemental screens Size 500.001 to 20000 kW	Insurance is $2,000,000 above 2 MW to 5 MW and $3,000,000 above 5 MW to 20 MW. Above 5 MW there is no Seattle program compensating exports at all. Application fee per the underlying distribution policy Liability insurance by band

The screens that decide it

Within the 100 kW net metering ceiling Limit 100 kW.
Net metering is capped at 100 kW with three named exceptions: a Living Building Pilot building may net meter up to 250 kW, a building outside Seattle in Seattle City Light territory certified under the Living Building Challenge before 31 December 2025 may reach 250 kW, and affordable housing meeting high efficiency standards may reach 500 kW. Above the cap, the Large Customer Renewable Generation Program applies to 5,000 kW.
Within the shared secondary transformer rating and 3 percent voltage rise
On a shared secondary the aggregate capacity must not exceed the secondary transformer nameplate, and must not create a voltage rise above 3 percent on the secondary wire or transformer. Both are utility data.
Penetration against feeder minimum load, with fifteen percent only as a fallback 100 percent of line section minimum load, a figure only the utility holds.
The primary screen is 100 percent of anticipated minimum load on the feeder or line section, using daytime minimum load for solar and absolute minimum load for everything else including solar plus storage. The fifteen percent of annual peak load screen applies only where twelve months of minimum load data are not available to the utility. Existing resources already reflected in minimum load are excluded to avoid double counting.

Ask the utility this, before you sell it

Is there twelve months of minimum load data for this feeder? Which screen applies turns on the answer, and the fifteen percent fallback is the stricter one.
What is the current queue position and has any upstream applicant withdrawn? Queue position decides who pays for system upgrades, and a withdrawal ahead of you can trigger re evaluation and change your cost.
What are the Level 3 and Level 4 application fees? The handbook confirms they exist and points to the underlying distribution policy rather than stating them.

Worth knowing before you quote

Seattle City Light does not issue pre application reports on conditions at a point of common coupling, so a site cannot be pre screened. A safety disconnect switch is required on every system at any size under Washington worker safety law. Any change to resource type, location or nameplate capacity after queue assignment forfeits the queue position and requires a new application, so a redesign is not a revision. Downtown network customers cannot export at all. On the looped radial system a non export scheme may be a certified power control system, a nameplate no greater than 50 percent of the host facility minimum load over the past twelve months, or a reverse power flow relay. Net metering credits are valued at the retail rate, accrue from 1 April to 31 March, and are cleared out on 31 March under RCW 80.60.030. Published clocks are all in business days: completeness 10, Level 1 screen 15, Level 2 screen 20, agreement sent 5, applicant returns 10, countersigned agreement and permission to construct 5.

Source

Seattle City Light Distributed Energy Resources Interconnection Handbook, 2026 Edition, with Seattle Municipal Code 21.49.082 and 21.49.083 and Construction Standard 0097.03

Read and recorded 2026-09-12. Publicly owned utility, outside its state's interconnection rule. Its own published documents govern. Washington RCW 80.60 does bind Seattle City Light for net metering, which is where the 100 kW eligibility line and the 31 March credit reset come from. Interconnection terms are the utility’s own.

All Washington interconnection rules

Size bands and what each one obliges

The screens that decide it

Ask the utility this, before you sell it

Worth knowing before you quote

What to do with this