Washington State Solar Energy: History, Prices, Capacity, and Data Accuracy

Student project by Anas Mohamed and Mauro Martinez

Overview

Washington State’s solar market has grown over time, with much of the earlier growth coming from residential customer-sited systems.

  • The historical dataset includes 7,462 Washington solar installations from 2011 through 2019.
  • About 92.1% of those systems are single-family residential installations.
  • Washington now has approximately 955 megawatts of installed solar capacity.
  • The state has about 60,227 solar installations.
  • These systems represent about $2.3 billion in solar investment.
  • Installed solar can produce enough electricity to power approximately 103,115 homes.

Solar Prices and System Size

The historical data shows that solar systems generally became larger while the installed price per watt decreased.

  • Median system size increased from 4.8kW in 2016 to 9 kW in 2019.
  • Median installed price decreased from $4.34/W in 2016 to $3.34/W in 2019.
  • As of August 2026, the average residential solar price in Washington is about $2.55/W.
  • The average quoted residential system size is about 13.48 kW.

Current Solar Growth

Washington solar continued to grow after the historical dataset ended.

  • Solar provides about 1.25% of Washington’s electricity.
  • The solar industry supports approximately 1,093 jobs in the state.
  • SEIA projects continued growth in Washington’s installed solar capacity cover the next five years.

Policies Supporting Solar Development

Several policies and programs have helped support solar development in Washington:

  • Net metering allows eligible customers to receive credit for electrivity sent back to the grid.
  • The Clean Energy Transformation Act requires electric utilities to move toward carbon-neutral electricity by 2030.
  • The law also requires electricity from renewable or non-emitting resources by 2045.
  • In 2025, the Washington State Department of Commerce awarded $41.1 million to 49 clean-energy community projects across 22 counties.
  • Funded projects included rooftop solar, battery storage, building decarbonization, and electric-vehicle charging.

Why Data Accuracy Matters

Accurate data is important when comparing solar projects and understanding market trends.

  • Missing records can create misleading trends.
  • Incomplete years can make solar growth appear higher or lower than it actually was.
  • Incorrect units can make project costs difficult to compare.
  • The historical dataset is especially useful for residential solar, but it does not represent every type of solar project in Washington State.

Impact

Washington’s solar market continues to grow as system sizes increase and the cost per watt generally decreases. This project shows that price, system size, capacity, policy, and data quality all need to be considered together when evaluating solar development.

Accurate information and supportive energy policies will remain important for future clean-energy planning in Washington State.

Resources

Full Report