Solar yield in Seattle
Seattle sits at 47.61°N in Washington, United States. The annual average is 3.5 h peak sun-hours per day.
A Seattle-based 400 Wp array generates an estimated 404 kWh per year — after a 78% system efficiency factor (MPPT, wiring, inverter losses).
Monthly solar generation in Seattle
Average daily kWh per month for common solar array sizes
Design your full off-grid system
Use the SOLARIS calculator to size a complete off-grid LiFePO4 system for Seattle: battery bank, inverter, cable cross-section, fuses and a wiring diagram. Pin your exact location on the map for live NASA POWER data.
Open the calculator →How we calculated this
Daily generation = panel Wp × peak sun-hours × system efficiency (0.78). Sun-hour values are 20-year averages from NASA POWER, sourced for Seattle's coordinates (47.61, -122.33). Real conditions vary by panel tilt, orientation, shading and weather — use the live calculator for site-specific results.