Improvement Valuation of Commercial Solar Energy Systems

March 16, 2023


Illinois uses a specific formula to value commercial solar energy systems for property tax purposes in counties with fewer than 3 million inhabitants. "Commercial" in this sense means that the system is used primarily to generate electricity for wholesale or retail sale, rather than referring to the customer class.

The valuation formula is calculated by substracting allowance for physical depreciation from the trended real property cost basis (set at $218,000 per MW of nameplate capacity in 2018, with adjustments for CPI inflation). More information is available here.

Program Overview

Implementing Sector: State
Category: Financial Incentive
State: Illinois
Incentive Type: Property Tax Assessment
Web Site:
Administrator: Illinois Department of Revenue
Start Date:
Eligible Renewable/Other Technologies:
  • Solar Photovoltaics


Name: Public Act 100-0781
Date Enacted: 08/10/2018


Name: Illinois Department of Revenue
Organization: Illinois Department of Revenue
Phone: (180) 073-2886

This information is sourced from DSIRE; the most comprehensive source of information on incentives and policies that support renewables and energy efficiency in the United States. Established in 1995, DSIRE is operated by the N.C. Clean Energy Technology Center at N.C. State University.