ROI and Payback Period for a 100 kW Solar System

To illustrate the financial and environmental feasibility, let’s consider a 100 kW rooftop solar PV installation for a mid-sized commercial facility in the U.S.:

Parameter	Typical Value (2025 Estimates)	Notes
System Size	100 kW DC	Standard commercial setup
Average Installed Cost	$180,000 – $250,000	Around $1.80–$2.50 per watt (SEIA 2025 data)
Federal Investment Tax Credit (ITC)	30 %	Reduces upfront cost to ≈ $126,000–$175,000
Annual Electricity Generation	140,000 – 160,000 kWh	Depends on solar irradiance (4–5 peak sun hours/day)
Annual Utility Savings	$18,000 – $24,000	Based on $0.13–$0.15 per kWh rates
Simple Payback Period	6 – 8 years	After incentives; shorter in high-rate regions
System Lifespan	25 – 30 years	Panels typically warrantied for 25 yrs
Estimated IRR (Internal Rate of Return)	9 % – 14 %	Comparable or better than many low-risk investments
Annual CO₂ Offset	≈ 90–110 metric tons	Equivalent to removing ~25 cars/year

Locations with higher electricity costs (California, New York, Hawaii) or strong state incentives (e.g., Illinois SREC, Massachusetts SMART) can shorten the payback to 5 years or less.

When coupled with battery storage, total investment rises 20–30 %, but peak-shaving savings and energy resilience often justify the added cost, especially for critical operations.

Explore Cost-Saving Models

Installing renewable systems can be expensive upfront, but new financing models make it easier.

One of the best options is a Power Purchase Agreement (PPA).
Here’s how it works:

• A third-party company installs and owns the system.
• Your business buys the energy it produces at a fixed, lower rate.
• You get clean power without paying large upfront costs.

Alternative Models

Model	Ownership	Upfront Cost	Maintenance	Typical Users
Direct Purchase	Business	High	In-house	Large corporations
Lease	Third party	Medium	Shared	Retail chains
Energy-as-a-Service	Provider	Low	Provider	SMEs/startups

These models stabilize long-term energy costs and protect against fossil-fuel price volatility—a growing competitive advantage in uncertain energy markets.