Grid & off-grid

Net metering calculator, Washington

Model your solar bill under Washington's full retail net metering, a right that holds statewide until a 2029 sunset or a utility's own 4% capacity cap, whichever comes first.

Your numbers

1 Project details Optional
Shown on your exported report. Leave blank to skip.
2 Your usage and system
Find this on a recent utility bill, usually labeled kWh used.
Use your quoted or planned system size. Panel count times panel wattage divided by 1,000 gives a rough figure.
Solar production swings seasonally; pick a specific month type to see how your bill shifts.
Most utilities charge a flat customer or connection fee regardless of usage.
3 Your location and rate
Defaulted to Washington's average peak sun hours. Adjust if you know your local figure.
Defaulted to Washington's current average residential rate. Your utility's actual rate may differ.
Washington typically credits exports around 100% of retail. Full retail net metering up to 100 kW under state law.
Some utilities charge progressively higher per-kWh rates as monthly usage climbs into higher tiers.
Accounts for inverter loss, wiring loss, dust, and temperature derate combined.
Informational only. A monthly cycle means unused export credit does not carry to the next bill; annual and rolling cycles do.

How it works

Three steps to your Washington solar bill estimate

Step 1

Enter your usage, system size, and season

Pull your monthly kWh from a recent bill and enter your planned or quoted system size in kW. Since unused Washington credits are forfeited every March 31 rather than paid out, avoid oversizing a system well beyond your annual usage. Select a season to model a specific month rather than only an annual average.

Step 2

Confirm your rate, tier, and export credit

A typical Washington residential rate and full retail export credit are filled in by default, matching the statutory structure most utilities still offer. Swap in your own tariff numbers and fixed monthly fee if you have a recent bill showing them.

Step 3

Compare the result to a full retail scenario

Since Washington already credits exports at full retail, the net billing vs net metering comparison tool is most useful here for seeing what a lower-credit successor rate like PSE's might eventually cost you.

How net metering works in Washington

Full retail crediting, but with a statutory sunset built in

Washington law (RCW 80.60) requires electric utilities to offer 1:1 net metering at the full retail rate for systems up to 100 kW. That requirement runs until the earlier of June 30, 2029, or the point at which a utility's cumulative net-metered capacity reaches 4% of its 1996 peak demand, whichever comes first, a hard-coded expiration unlike most states on this list.

Some utilities are already close to their capacity cap

Puget Sound Energy has already passed its statutory 4% cap, reaching it in June 2024, and continues offering net metering voluntarily under its Schedule 150 tariff while it decides whether to propose a successor rate structure to the Utilities and Transportation Commission. Any such proposal needs commission review before taking effect, which is why solar advocates describe now as a meaningful window to lock in today's terms before PSE files one.

A statewide study is actively shaping what comes next

The Washington State Academy of Sciences is conducting a Value of Solar and Storage (VOSS) study, expected to conclude in October 2026, intended to give regulators a data-driven basis for whatever compensation structure eventually replaces straight 1:1 net metering. A 2025 proposal from PacifiCorp to cut export compensation by 66% was delayed by the Utilities and Transportation Commission specifically pending this study's results. The avoided cost rate calculator can help you understand what a future value-of-solar rate might be built from.

Unused annual credits are forfeited, not paid out

Washington's net metering credits roll forward month to month, but any balance still unused on March 31 each year is forfeited entirely, granted to the utility without compensation to the customer. This makes sizing a system to closely match annual usage more valuable here than in states offering an annual cash-out at some reduced rate, and the self-consumption battery size calculator can help a slightly oversized system avoid losing credits to the March 31 forfeit.

Interconnection and the off-grid comparison

Connecting a system through any of Washington's three major investor-owned utilities, Puget Sound Energy, Avista, or Pacific Power, still requires standard interconnection review; the grid interconnection cost estimator covers what to expect there, and the tax credit and rebate estimator for Washington can total up what incentives apply on top of net metering. And with full retail net metering still in place statewide, staying grid-tied remains far cheaper than going fully off-grid in Washington, and the grid tie vs off grid comparison tool shows how much cheaper.

Questions

Frequently asked

Washington law requires 1:1 full retail net metering up to 100 kW, but the requirement ends once a utility's capacity reaches 4% of its 1996 peak demand, or June 2029, whichever comes first. Puget Sound Energy already passed that cap in June 2024 and now offers net metering voluntarily.

The average residential rate in Washington was about 14.9 cents per kWh as of September 2026, per EIA data, up sharply, about 15%, from a year earlier. Full retail net metering up to 100 kW under state law, though the requirement is set to end by 2029 or sooner at the utility's capacity cap.

The statutory requirement runs until the earlier of June 30, 2029, or the point at which a utility's net-metered capacity reaches 4% of its 1996 peak demand. Puget Sound Energy already passed that threshold in June 2024 and continues net metering voluntarily under its Schedule 150 tariff, so other utilities could hit it well before 2029 too.

They're forfeited. Any credit balance still unused on March 31 each year is granted to the utility entirely, without any compensation to the customer, unlike states that pay out remaining credits at a reduced rate rather than losing them outright.

Related tools

Compare Washington's policy to other structures

Grid tie vs off grid comparison Net billing vs net metering Buy all sell all vs net metering Avoided cost rate calculator Grid export cap calculator Grid interconnection cost estimator Grid tie with battery backup comparison All grid and off-grid tools