Understanding the Residential Solar and Battery Permitting Process in Washington State
Installing solar panels and battery storage systems in Washington State is an excellent way to reduce your carbon footprint, increase energy independence, and save on electricity bills. But before you can start harnessing the power of the sun, it’s critical to understand the permitting and interconnection process that ensures your system is safe, code-compliant, and utility-ready.
Step 1: Electrical Permits
All solar photovoltaic (PV) and battery storage systems in Washington require an electrical permit. This is typically issued by the Washington State Department of Labor & Industries (L&I) or your local authority if they have their own permitting department.
Key Points:
- Electrical permits are mandatory for new installations, system expansions, repairs, or maintenance.
- They ensure compliance with safety standards and the National Electric Code (NEC), especially Articles 690 (solar PV) and 706 (energy storage).
- Installers or project managers handle the permit application and schedule inspections.
- Bellevue permitting may take up to 2 months, so plan accordingly.
- In emergency or time-sensitive cases, expedited permits or feeder permits can be submitted in person at the permit center.
Step 2: Building Permits (When Needed)
Building permits are not always required for rooftop residential solar systems, but here are exceptions:
- Your home is pre-manufactured and requires stamped engineering plans.
- The system is ground-mounted, which may require environmental review depending on your jurisdiction.
Local Notes:
- Seattle, Kirkland, and Bellevue often require building permits for structural upgrades or if the installation is part of new construction.
- Cities like Issaquah may exempt residential rooftop systems from building permits, but electrical permits are still mandatory.
Battery Storage & Fire Code Compliance
Battery systems in Washington must meet evolving fire and safety codes. Since mid-2024, stricter rules have been defined—especially in Seattle, Redmond, and Kirkland.
Key Requirements:
- Indoor batteries must have clearances from windows and be paired with heat detectors.
- Outdoor batteries need proper setbacks and fire-resistant spacing.
- Plan sets must be accurate and include listed equipment with UL certifications.
- Incomplete or incorrect plan sets are a top cause of permit delays or inspection failures.
Project Timeline & Inspections
Permit processing and inspection timelines vary across cities:
- Bellevue: Solar permits may take up to 2 months.
Types of inspections you may encounter:
- Pre-construction inspection – Verifies that listed equipment matches plan set (required in Bellevue, Seattle, Kirkland).
- Rough-in inspection – For new construction before wiring is concealed.
- Reconnect inspection – Required if utility power is shut off or when installing/upgrading SPAN/main panels.
- Final inspection – Confirms code compliance and operational safety.
All inspections are typically scheduled by your installer’s Project Manager.
Utility Interconnection: PSE & SCL
Interconnection agreements are required for grid-tied systems to operate with utilities.
Puget Sound Energy (PSE):
- 2–3 weeks for Approval to Construct (ATC)
- 1.5–2 weeks for Permission to Operate (PTO)
- Installations over 25 kW AC require a knife-style disconnect
Seattle City Light (SCL):
- Similar timeline to PSE
- Requires knife-style disconnects for all generating sources
Note: Plan sets must be precise to avoid delays in utility approval.
Snohomish PUD (SnoPUD)
- Systems over 78 kW AC require a 3-phase service upgrade.
- Interconnection process includes online application, signed agreement, and proof of equipment compliance.
- Typically 2–4 weeks for full review and PTO depending on system size.
Tacoma Power
- Offers a straightforward interconnection for systems under 25 kW.
- Requires a signed Net Metering Interconnection Agreement and permit approval documentation.
- Additional review for battery systems may be needed to verify system isolation.
Avista Utilities
- Requires a net metering application, system diagram, and single-line electrical drawing.
- Customer must provide proof of electrical inspection and L&I permit number before PTO.
Clark Public Utilities
- Application and interconnection process managed via an online portal.
- Allows grid-tied solar and storage systems up to 100 kW.
- Often requires on-site utility inspection prior to meter swap or final PTO.
AHJ Coordination
For all utilities, timely interconnection depends on clear coordination with local Authorities Having Jurisdiction (AHJs). Your installer should ensure:
- Accurate plan sets
- Proper disconnect type and labeling (as required by each utility)
- Verification of final inspection by L&I or local building departments
Be sure to check with your utility or rely on your installer to confirm the exact documentation and steps required for your specific project.
HOA's and Solar
Washington law protects homeowners’ rights to install solar energy systems.
- HOAs cannot prohibit solar, but may regulate placement and aesthetics.
- Installers typically provide homeowners with a package to submit to their HOA: plan set, spec sheets, permits, and UL listings.
- Most HOAs approve quickly when given the correct documentation.
Reference: RCW 64.38.055
Final Tips for a Smooth Permitting Process in Washington
Northwest Electric and Solar (NWES) is committed to meeting—and exceeding—all permitting and interconnection requirements, no matter the project size, utility, AHJ, or HOA. Our team of experienced, licensed professionals ensures compliance with the most up-to-date fire codes, electrical standards, and utility interconnection rules.
- We prepare accurate plan sets, coordinate inspections, and proactively manage communications with permitting offices to avoid costly delays.
- Whether it’s an expedited feeder permit, knife-style disconnect, or HOA approval documentation, NWES handles every detail so you don’t have to.
With NWES, your solar and battery project is in expert hands—built to code, utility-ready, and designed for a resilient, renewable future.
