Solar Carport Calculator
Carport dimensions and capacity from parking layout.
About this calculator
Sizing a solar carport starts from the parking lot, not the roof — this calculator works forward from the number of spaces you're covering and a canopy footprint per space (around 170 sq ft by default, accounting for the overhang beyond a standard 9x18 ft stall) to arrive at total covered area. From there it estimates how many panels physically fit by applying an 85% usable-area factor (the rest goes to structural framing, support columns, and clearance gaps) and dividing by each panel's physical area, which itself scales proportionally from a 17.6 sq ft reference size for a 400W commercial module. That panel count sets your system's DC capacity and, from peak sun hours and a system derate factor, its annual production.
Costs are broken into three genuinely separate line items rather than one blended number: the solar equipment itself at your entered cost-per-watt, a fixed structural premium of $2,500 per parking space for the elevated canopy framing (carports cost meaningfully more than ground-mount or rooftop per watt because of this structure), and $6,500 per Level 2 EV charger if you're integrating charging. EV charging is also modeled as a small revenue stream — assuming 3 charging sessions of 8 kWh each per day at a $0.10/kWh margin — that adds to annual electricity savings when computing simple payback. The structural and charger cost figures are fixed assumptions baked into the code, not adjustable inputs, so treat this as a first-pass feasibility sizing tool and get a structural engineer's canopy quote before finalizing project economics.
Inputs
Results
System capacity (kW DC)
328.4
How to Use This Calculator
- Enter the number of parking spaces to be covered and canopy area per space in sq ft.
- Set panel wattage, peak sun hours, and system derate factor.
- Enter solar cost per watt DC and current electricity rate.
- Input the number of EV chargers to install on the carport.
- Review system capacity, annual production, total project cost, and simple payback years.
How the result changes with Parking spaces covered
| Parking spaces covered | System capacity (kW DC) |
|---|---|
| 50 | 164 |
| 75 | 246 |
| 150 | 492.4 |
| 250 | 820.8 |
What each input means
- Parking spaces covered
- Number of parking spaces under the solar canopy.
- Canopy area per space (sq ft)
- Canopy coverage per space including overhang. Standard is ~170 sq ft.
- Panel wattage (W)
- STC wattage per panel.
- Peak sun hours (PSH)
- Average daily peak sun hours at location.
- System derate factor
- Overall system efficiency.
- Solar cost ($/W DC)
- Solar module + inverter installed cost per watt (excludes canopy structure).
- Electricity rate ($/kWh)
- Current commercial electricity rate.
- EV chargers installed
- Number of Level 2 EV chargers to install on the carport.
What each result means
- System capacity (kW DC)
- Total solar array capacity on the carport.
- Number of panels
- Panels that fit on canopy with 85% fill factor.
- Total canopy area (sq ft)
- Total covered area.
- Annual production (kWh)
- Expected yearly electricity generation.
- Total project cost ($)
- Solar + structure + EV charger costs.
- Annual electricity savings ($)
- Value of solar electricity produced.
- Total annual benefit ($)
- Electricity savings + EV charging revenue.
- Simple payback (years)
- Years to recoup investment before incentives.
- Watts per parking space
- Solar capacity per covered parking space.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersParking spaces covered = 100, Canopy area per space (sq ft) = 170, Panel wattage (W) = 400, Peak sun hours (PSH) = 5 = 8 input(s) provided
- Calculate System capacitySystem capacity = (panelCount * panelWatts) / 1000328.4 = 328.4
- Calculate Number of panelsNumber of panels = floor(usableAreaSqFt / panelAreaSqFt)821 = 821
- Calculate Total canopy areaTotal canopy area = parkingSpaces * canopyAreaPerSpace17000 = 17000
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does a solar carport cost more per watt than the same system on a rooftop or on the ground?
A carport has to hold itself up over an active parking lot with no roof or ground beneath it, so it needs an elevated steel or concrete structure engineered to span rows of parking and support both the panels and traffic clearance underneath. This calculator prices that structure as a separate $2,500-per-space line item on top of the solar equipment cost, which is why total project cost per watt comes out meaningfully higher than a comparable rooftop or ground-mount system priced at the same cost-per-watt input.
Can I adjust the $2,500 per-space structural cost or the $6,500 per-charger EV cost?
No — both figures are fixed assumptions built into the calculation rather than exposed inputs, based on typical canopy structure and Level 2 commercial charger installation costs. If your actual quotes differ significantly, you'll need to substitute your own numbers manually rather than adjusting an input field.
Where does the EV charging revenue assumption (8 kWh, 3 sessions, $0.10 margin) come from?
It's a simplified utilization estimate: each charger is assumed to deliver about 3 charging sessions per day averaging 8 kWh apiece, with a 10-cent-per-kWh margin retained after electricity cost — roughly modeling a workplace or retail charging pattern rather than a high-turnover fast-charging site. Actual utilization varies enormously by location and pricing strategy, so this revenue line should be treated as a rough planning estimate rather than a site-specific forecast.
Why is only 85% of the total canopy area usable for panels?
The remaining 15% is consumed by structural elements that can't hold panels — support columns, purlins, edge clearances, and gaps needed for drainage and maintenance access. The calculator applies this fill factor to total canopy area before dividing by each panel's physical footprint to determine how many panels actually fit.
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