As solar panels increase your property’s value, it’s good to know that in Illinois you can take advantage of a solar-specific property tax exemption — meaning you won’t necessarily pay more tax just because you added a solar system.
What Is the Solar Property Tax Exemption?
Under Public Act 100‑0781 (amending the Illinois Property Tax Code, 35 ILCS 200/10-5) the state policy is that solar energy systems “should be encouraged” and should be valued in relation to their benefits, not penalized.
For residential and many business systems, this means:
- If you install a qualifying solar energy system primarily for on-site consumption, it may be excluded from the added assessed value that would otherwise raise your property taxes. Read more
- The system’s value is compared to what the property’s improvements would be if it were equipped with a “traditional” system; the lesser value becomes the base for assessment. Read more
How Do I Claim the Solar Property Tax Exemption?
This is not an automatic process. To request a special assessment, property owners need only file Form PTAX-330 with their county assessment office.
What Happens During a Special Assessment?
When you apply, your assessor will evaluate:
- The lower of those two values is used to determine your assessed value for tax purposes.
- The value of your property improvements with the solar system installed.
- The value of your property improvements with a comparable conventional energy system instead (if the solar system were not installed).
This ensures that your solar system doesn’t inadvertently raise your assessed value more than a traditional energy upgrade would.
What Equipment Is Eligible?
- Eligible equipment includes:
- Solar energy systems (active photovoltaic, solar thermal) installed primarily for on-site consumption.
- Both roof-mounted and ground-mounted systems may qualify depending on their use.
- Equipment not eligible includes:
- Systems primarily used for wholesale or retail sale of electricity, unless they fall under separate commercial valuation rules.
- Components not integral to the solar energy generation system (e.g., structural modifications, insulation added solely for non-solar benefit).
Key Things to Know (November 2025)
- This property tax treatment applies as long as the solar system remains operational and continues to serve the property for which it was installed.
- For commercial ground-mounted solar (systems producing for off-site consumption) different rules apply: e.g., valuation method under 35 ILCS 200/10-720 et seq.
- Filing the application (PTAX-330) is your responsibility — make sure to do this with your county assessor after system installation.
- Even though your property may appreciate because of solar, this exemption prevents the solar-specific value from raising your assessed tax value above what it would have been with a standard system.
- Consult your local assessor’s office or property tax professional, because counties may have slightly different procedures or timelines.
How Sun Collectors Can Help
At Sun Collectors, we’re pleased to include guidance on the property tax exemption as part of our solar‐consultation process. We will:
- Explain eligibility for the exemption and what your county requires.
- Help you gather documentation and form the PTAX-330 if needed.
- Incorporate the tax‐exemption benefit into your solar investment return modelling.
- Answer questions about how the exemption interacts with other incentives like the federal tax credit or REC programs.
You can reach out to your solar consultant directly, contact us online or call (309) 323-8260 if you have questions or need help.
