Solar Panel Installation Cost Calculator

Solar installation cost overview

These ranges reflect $2.50–$3.75 per watt before any incentives. The federal residential solar tax credit (Section 25D) has expired for expenditures made after December 31, 2025, so this calculator does not assume a federal credit applies — verify current state, local, or utility incentives with your installer or a tax professional.

How it works

Solar Installation Cost by System Size

Ranges reflect $2.50–$3.75 per watt before incentives and vary by panel type and roof/mounting complexity. Does not assume any federal tax credit — the residential solar credit expired after 2025.

What's included — and what's often extra

What moves the price

• System size. A bigger array costs more in total but less per watt — a 10kW system usually beats a 4kW on $/W.
• Panel type & efficiency. Premium monocrystalline costs more than value-tier panels but needs less roof space for the same output.
• Inverter choice. Microinverters or power optimizers add roughly $0.20–$0.40/watt over a plain string inverter.
• Roof type & complexity. Tile, steep pitches, and multi-plane roofs raise labor; ground mounts add racking and trenching.
• Electrical work. An older 100A panel often needs a $1,500–$4,000 upgrade to 200A before solar can be added.
• Local labor & permitting. Costs vary widely by state and by your permitting authority (AHJ).

Panel types & efficiency

• Monocrystalline (19–22%). The default for most homes — highest efficiency, best when roof space is limited, typically 25-year product and performance warranties.
• Polycrystalline (15–17%). Cheaper per panel but needs more roof area for the same output; increasingly rare on new installs.
• Thin-film (10–13%). Lightweight and inexpensive, but rarely used on residential roofs because it needs far more space.

Modern panels are 350–450W each and degrade about 0.5% per year, so a good panel still produces ~85–90% of its original output after 25 years.

Inverters: string, microinverter, or power optimizer

• String inverter. Cheapest option — one central unit for the whole array. A single shaded or underperforming panel drags down the entire string.
• Microinverters (e.g., Enphase). One per panel — best for shading and complex roofs, with panel-level monitoring. Costs more but maximizes production.
• Power optimizers (e.g., SolarEdge). Per-panel optimization paired with a central inverter — a middle ground on price and performance.

Incentives after the federal credit expired

The 30% federal residential solar credit (Section 25D) expired for systems placed in service after December 31, 2025, so this calculator does not assume a federal credit. What may still lower your cost:

• State income-tax credits and cash rebates
• Utility rebates and performance-based incentives
• SREC markets (New Jersey, Massachusetts, Maryland, and others)
• Net metering or net billing for the power you export
• Property-tax and sales-tax exemptions on the system

Check DSIRE (dsireusa.org) and your utility for current programs. This is not tax advice — confirm eligibility with a professional.

Pay cash, finance, or lease?

• Cash. Lowest lifetime cost and best return — you own the system and keep every incentive.
• Solar loan. Often $0 down; interest raises the total but you keep ownership and any incentives.
• Lease / PPA. Little-to-no money upfront, but the provider owns the system and keeps the incentives, so your savings are the smallest.

Questions to ask an installer & red flags

• Is the quote itemized — panels, inverter, labor, and permits — with panel wattage and model numbers?
• What's the modeled production (kWh/year), and does it account for your roof's shading and orientation?
• What are the panel, inverter, and workmanship warranties — and who honors them if the installer closes?

Red flags: high-pressure "today-only" pricing, vague "eliminate your bill" savings claims, or any quote that still advertises a 30% federal tax credit for a 2026 install.