Solar Pergola Calculator
How many panels fit, how much power you'll generate, structural load, project cost, and dual benefit from solar production and shade cooling.
How to Use This Calculator
Enter your pergola dimensions
Use the preset size buttons (10×10, 12×12, 12×16, 14×20) for standard pergola sizes or enter custom dimensions. The calculator uses a standard 400W panel at 6.8×3.4 ft to determine how many panels physically fit within your pergola footprint based on your desired coverage percentage.
Set panel coverage percentage
Coverage controls how much of the pergola roof is covered by solar panels. 50-60% creates dappled light for a garden feel. 75-85% provides substantial shade while allowing some filtered light. 100% is a fully solid solar roof — maximum production and maximum shade, but darker underneath. Most homeowners prefer 70-80% for a balance of shade and ambiance.
Select your peak sun hours
Peak Sun Hours (PSH) represent the average daily solar irradiance. The Southwest US gets 5.5-6.5 hours; the Northeast gets 3.5-4.5 hours. Your actual PSH depends on precise location, roof orientation, and shading — the pergola facing south at 15-30° tilt will maximize production, though many are installed flat which reduces output by 10-15%.
Review the dual-benefit summary
A solar pergola delivers two forms of savings: electricity production (solar value) and shade reduction in AC load (cooling value). The shade benefit depends on climate — in Phoenix, shading a patio can reduce HVAC use significantly; in Minneapolis, less so. The combined annual benefit is what you compare against total project cost for payback calculation.
The Formula
The 0.80 efficiency factor accounts for inverter losses (~97%), wiring losses (~1-2%), temperature derating (~3-5%), and soiling (~2-3%). A flat-mounted pergola (no tilt) may see an additional 5-15% reduction vs. an optimally tilted roof array in the same location.
Example
The Patels — Phoenix, AZ — Pool deck 12×16 pergola
The Patels want to add a solar pergola over their 12×16 pool deck. Phoenix gets 6.0 peak sun hours and their electricity rate is $0.13/kWh.
With total project costs of $12,000-$17,000 (pergola + solar after ITC), the Patels see a payback of 16-23 years on solar economics alone — but the pergola provides a usable outdoor space the whole family enjoys, making the dual benefit math more compelling. The pergola would cost $5,000-$8,000 regardless; solar adds incremental payback.