Commercial & small business

Commercial solar 25-year TCO calculator

Add up every dollar your system will cost over 25 years, not just the upfront price. Get a total cost of ownership figure and a levelized cost per kWh you can compare directly to your utility rate.

Your numbers

1 Project details Optional
Shown on your exported report. Leave blank to skip.
2 Your system
From your installer's proposal, or the size by square footage tool.
US commercial systems typically run $1.10 to $1.80 per watt before incentives.
Use your installer's estimate, or the capacity factor calculator.
Most manufacturers warranty output at roughly 85% to 88% of original after 25 years.
3 Ownership costs over 25 years
Typical commercial O&M runs $15 to $25 per kW per year.
Typically $0.10 to $0.15 per watt for a central or string inverter swap.
Leave blank if monitoring is bundled into your O&M line above.
4 Incentives and electricity comparison
Check the ITC calculator if you're unsure which rate applies.
Leave blank if your state or utility doesn't offer one.
What you'd otherwise pay the utility per kWh today.
US and Canadian utility rates typically rise 2% to 4% a year.

How it works

Three steps to your 25-year TCO

Step 1

Start with your net upfront cost

Get an installer quote for total system cost, then confirm your ITC rate with the ITC calculator. That net figure becomes the foundation of your total cost of ownership.

Step 2

Add ongoing costs across the system's life

Enter your annual O&M, an inverter replacement around year 10 to 15, and any monitoring plan fee. These are the costs a simple payback calculator usually leaves out.

Step 3

Compare your levelized cost to the grid

Enter your blended electricity rate and expected escalation. We'll show your cost per kWh from solar next to what you'd pay the utility over the same 25 years. Cross-check with the 10-year grid comparison tool for a shorter horizon.

Understanding your commercial solar TCO

What TCO includes that payback and ROI leave out

Most commercial systems land between $0.03 and $0.07 per kWh over a 25-year lifespan, once every cost is added up. A 150 kW system with a $233,500 total cost of ownership, producing about 5.08 million kWh over 25 years, works out to roughly $0.046 per kWh, well below a typical commercial grid rate. TCO catches costs that a simple payback number often misses, especially the inverter replacement that most systems need once between year 10 and year 15.

Why levelized cost per kWh is the most honest comparison

Comparing a lump-sum system cost to a monthly utility bill doesn't tell you much on its own. Converting your full 25-year cost into a per-kWh figure gives you a number that lines up directly with your utility rate, so you can see the real spread. Run the ITC calculator and MACRS depreciation calculator first if you want to sharpen the upfront cost side of this figure, and the DOE-funded Levelized Cost of Energy Calculator walks through this same capital-cost-to-per-kWh math in more technical detail. A commercial roof has its own costs and limits. The roof inspection cost before solar estimator in our Solar + Roofing Integration section can help you check whether your roof is ready before you commit to a size.

Inverter replacement: the cost most estimates skip

String and central inverters typically carry a 10 to 15 year warranty, shorter than the panels themselves, so most systems need at least one replacement during a 25-year life. Budgeting $0.10 to $0.15 per watt for that swap keeps your TCO realistic instead of assuming zero maintenance for a quarter century, and the 25-year degradation curve tool can help refine the lifetime production estimate this whole figure depends on. A size estimate is only half the decision for a business. The quick financing comparison tool in our Financing section can help you work out which way to pay for the system costs less.

TCO versus payback versus NPV

Payback tells you when you break even, NPV tells you the dollar value created at a chosen discount rate, and TCO tells you the full lifetime cost converted into a single levelized rate. None of them is wrong, they just answer different questions. Pair this result with the payback calculator and NPV calculator for the complete picture, or the 25-year lifetime savings calculator in our savings and payback section for the same math from a residential-scale angle.

What this calculator doesn't account for

This model doesn't include MACRS depreciation tax savings, financing interest, or insurance costs, and it assumes a single inverter replacement rather than ongoing component repairs. For the tax-adjusted view, pair this with the payback calculator, which builds in year-one depreciation benefits, and the Department of Energy's guide to going solar for the broader cost and savings factors any lifetime estimate like this one is built from.

Questions

Frequently asked

Most commercial systems land between $0.03 and $0.07 per kWh over a 25-year lifespan, well below typical commercial grid rates of $0.09 to $0.18 per kWh. A 150 kW system with a $233,500 total cost of ownership, producing about 5,076,213 kWh over 25 years, works out to roughly $0.046 per kWh.

Most commercial inverters need replacement once between year 10 and year 15, typically costing $0.10 to $0.15 per watt. On a 150 kW system, that's an $18,000 line item, which is a meaningful but usually small share of total cost of ownership compared to the upfront system cost.

Yes, this calculator applies your federal ITC rate and any rebate to the upfront system cost before adding O&M, monitoring, and inverter replacement costs across the full 25 years. That net starting point is what makes the final levelized cost per kWh realistic.

Payback period tells you when you break even on your investment. TCO adds up every dollar spent on the system across its full life, including costs payback usually ignores like inverter replacement, and converts the total into a single cost per kWh you can compare directly against your utility rate.

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Commercial solar payback calculator Commercial solar ROI calculator Commercial solar NPV calculator Commercial solar IRR calculator Commercial ITC calculator MACRS depreciation schedule calculator Solar vs. grid-only, 10-year comparison All commercial & small business tools