New Commercial Solar
Existing Solar
Battery Only
Used to look up your utility rate, solar irradiance, and local incentives.
1
Your Building
sq ft
1
2
3+
Flat (ballasted)
Low-slope
Standing seam
Pitched (shingle/tile)
Ground-mount
Multi-zone
sq ft
Total roof area. Fire code setbacks & pathways (~33–40%) are deducted automatically.
M-F 8am-5pm
6 days
24/7
Roof Zones
Define up to 4 roof zones with different tilt and orientation. PVWatts runs per-zone. Tip: draw each roof section (or ground area) on the map below and zone areas fill in automatically.
2
Energy Profile
$
Your typical monthly commercial electric bill.
Auto-populated when you enter your address.
$/kW/mo
Peak demand charge on your commercial rate. Auto-estimated by building type.
kW
Highest monthly demand reading. Estimated from bill if unknown.
3
System Design
Cover 100%
Cover 75%
Maximize roof
Custom kW
Best Overall
Budget Pick
Performance
String (3-phase)
Central
Microinverters
None
Minimal (5%)
Moderate (15%)
Heavy (30%)
Severe (50%)
Bifacial panels? Best on flat commercial roofs with light-colored membranes (TPO/PVC).
Include commercial battery storage? Battery for demand charge reduction and backup power.
%
Federal 21% + state corporate tax. Used for MACRS benefit.
Cash
Commercial Loan
PPA
ITC Adders (IRA)
Prevailing wage & apprenticeship Projects under 1 MWac are statutorily exempt and always get the 30% base. This toggle only matters at 1 MW and above (otherwise 6%).
Domestic content (+10%) Steel, iron, and manufactured products meet domestic content thresholds.
Energy community (+10%) Located in a brownfield, coal community, or area with high fossil fuel employment.
Low-income community (+10% or +20%) Located in a low-income census tract or serving low-income residents.
Use Section 179 instead of MACRS? Full cost deduction in Year 1 (up to $1.16M cap). Best for smaller systems.
%/yr
Your cost of capital. Sets the net present value and the levelised cost, the test of whether this beats leaving the money elsewhere. 7% is the NREL default.
$/kW/yr
Monitoring, inverter service, washing and insurance. NREL puts commercial rooftop near $15/kW/yr.
%/yr
Historical average is ~2.5–3.5%/yr. Used for 25-year projections.
%/yr
Typical: 0.3–0.7%/yr. Premium panels degrade slower.
%
Includes wiring, soiling, mismatch, clipping. NREL default: 14%.
25 years
30 years
$/kWh
Monthly Production vs. Consumption
Solar generation (yellow) compared to building electricity usage (gray) by month.
Cumulative Savings Over Time
When your solar investment breaks even, including MACRS depreciation benefits.

What this estimate does not include

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This quote is the MEDIAN of what commercial customers actually paid, from a dataset of completed transactions, not a modelled best case. About half of comparable projects came in below it and half above. A buyer who shops hard and takes competitive bids should beat it by roughly 10%; that is the 20th percentile, and it is where published industry cost benchmarks tend to sit.

• Where you are within your state matters more than which state you are in. Across 17,562 completed commercial sales, your corner of the state explains roughly four times as much of the price as your state does, and the gap is widest at the 100–1,000 kW sizes this tool is built for, where the state you are in stops mattering at all. Expect around ±9% either side of our figure on location alone, and up to 40% between the dearest and cheapest parts of a single state. We adjust for state and genuinely cannot see the rest.

• But about half of that is who quotes you, not where you are. Following individual installers across areas, the same firm carries only about 43% of the local price gap with it, the rest is which companies happen to work in your area. That makes it worth getting a quote from a firm based outside your immediate area, because a good part of a local price premium travels with the installer rather than with the site.

• Interconnection study fees and utility upgrades are not included. These vary enormously by utility and can be trivial or project-defining, and no utility publishes them in a form we can look up.

• Roof repair or replacement is not included. If the roof has less remaining life than the array's 25-year warranty, doing both at once is usually cheaper than doing them separately.

• Structural reinforcement, ballast engineering, or snow and wind load remediation where a structural review requires it.

• Public and school projects cost more, and we apply that, measured at about +17.5% over private commercial, and closer to +50% on smaller school projects. If you are a public body, procurement rules are the most likely reason your bids exceed a private-sector benchmark.

Assumptions & Methodology

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