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Solar Carport Calculator

Find how many panels fit, annual production, EV miles powered, and total cost — compared to rooftop solar.

Carport size
Panel specifications
W
ft
ft
Location & financials
$/kWh
Solar panels that fit
17 panels
Carport area24 × 20 ft = 480 sq ft
System size6.80 kW
Annual production10,673 kWh/yr
Annual electricity savings$1,601/yr
EV miles powered per year37,354 miles
Carport structure cost (est.)$6,000
Solar installation cost (est.)$24,480
Total carport + solar cost$30,480
Payback period19.0 years
Same panels on roof instead$19,040 (save $11,440)
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How to Use This Calculator

Select your carport size

Choose the number of car bays — the calculator auto-fills standard US carport dimensions (1-car: 12×20 ft, 2-car: 24×20 ft, etc.). Enable "Custom dimensions" to override these if you have an existing carport or non-standard layout.

Adjust panel specifications

The defaults (400 W panel, 6.8 × 3.4 ft) match a standard 60-cell monocrystalline panel. If you're planning a specific panel model, enter its exact dimensions from the spec sheet. The calculator uses 85% of carport area as usable roof space — accounting for racking rails, edge gaps, and structural members.

Select your location

Peak sun hours vary from 3.5 in the Pacific Northwest to 6.5+ in the Desert Southwest. This directly determines how much electricity your carport solar generates. If your location isn't listed, use our Solar Irradiance Calculator for a precise value.

Understand the cost comparison

The results show the full carport + solar cost alongside what the same panels would cost installed on a roof. The difference is the structural premium for a carport system — typically $5,000–$15,000 more than rooftop for residential and $20,000–$80,000 more for commercial.

The Formula

Carport Area (sq ft) = Length × Width Usable Area = Total Area × 0.85 (15% for gaps, rails, structure) Panels That Fit = floor(Usable Area / Panel Area) System kW = Panels × Panel Watts / 1000 Annual kWh = System kW × Peak Sun Hours × 365 × 0.86 Annual Savings ($) = Annual kWh × Electricity Rate EV Miles/Year = Annual kWh × 3.5 miles/kWh Total Cost = Structure Cost + Solar Cost ($3.60/W installed) Payback Years = Total Cost / Annual Savings Rooftop Equivalent = System kW × 1000 W × $2.80/W (no structure)

EV miles use 3.5 miles/kWh — the US EPA average for popular EVs (Tesla Model 3 3.7 mi/kWh, Chevy Bolt 3.5 mi/kWh, Nissan Leaf 3.3 mi/kWh). Larger EVs and SUVs (Model X, Rivian) consume more — use 2.5–3.0 mi/kWh for those vehicles.

Example

2-car solar carport — Phoenix, AZ

A Phoenix homeowner builds a 2-car solar carport (24×20 ft) with 400 W panels, 6.0 peak sun hours, electricity rate $0.14/kWh.

Carport area480 sq ft (usable: 408 sq ft)
Panels that fit17 panels
System size6.8 kW
Annual production12,810 kWh/yr
Annual savings$1,793/yr
EV miles powered44,835 miles/yr
Total cost (structure + solar)~$30,500
Payback period~17 years
Same panels on roof~$19,000 (save $11,500)

The carport solar system pays for itself in about 17 years — longer than rooftop (11 years) due to the structural cost premium. However, the carport provides car shading and weather protection as additional value beyond electricity — benefits not captured in the payback calculation.

FAQ

Solar carports cost 25–40% more than rooftop solar for the same system size. Rooftop solar averages $2.50–$3.00/W installed. Solar carports range from $3.50–$5.00/W because of the engineered steel structure required. For a 6 kW system, a carport adds roughly $5,000–$12,000 in structural cost compared to rooftop. The carport provides value beyond electricity — covered parking, UV protection for vehicles, rain cover — that can justify the premium, especially for homeowners without suitable roof space or with south-facing driveways.
Solar carports typically require two permits: a building permit (structural engineering drawings, foundation specs, local building code compliance) and an electrical permit (solar interconnection, inverter, utility approval). Carport structures are subject to local wind and snow load requirements — hurricane zones and heavy snow regions may require more substantial and expensive structures. Check with your local building department before starting. HOA approval is also commonly required. Permitting typically adds $500–$2,000 in cost and 4–12 weeks of lead time.
Yes — this is one of the most compelling use cases for solar carports. A 6 kW carport produces roughly 12,000–15,000 kWh/year in a sunny location. At 3.5 miles/kWh, that powers 42,000–52,500 EV miles annually — more than most households drive. To maximize EV charging from the carport, install a Level 2 EVSE (J1772 charger, 7.2–11.5 kW) connected to a solar inverter with smart EV charging capability. Brands like SolarEdge, Enphase, and Tesla all offer integrated solar + EV charging solutions that automatically prioritize solar power for vehicle charging.
A solar carport structure must support dead load (panel weight ~2.5 lbs/sq ft), wind uplift (varies by location, typically 100–150 mph design wind speed), and snow load (0–50 lbs/sq ft depending on climate zone). The structure must be engineered and stamped by a licensed structural engineer in most jurisdictions. Standard residential solar carport materials: galvanized steel columns (4–6 in square) set in concrete footings, C-purlins or rectangular tube steel framing. For a 2-car carport, expect 4–6 concrete footings 12–24 inches in diameter and 3–4 feet deep.
Rooftop solar typically has a payback period of 7–12 years. Solar carports have a payback of 12–20 years due to the structural premium. However, the comparison changes if: (1) you count the covered parking value (saves car detailing costs, extends paint/interior life), (2) you have no suitable roof (shading, wrong orientation, complex shape), (3) you qualify for commercial solar ITC on the structure as well as the panels. Commercial parking canopy solar often pencils better than residential — the ITC at 30% applies to the entire installed cost including the structure.

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