Do solar panels raise your assessment in Illinois?
Illinois provides a special valuation for solar energy systems. It has to be claimed.
Illinois has a specific provision so that installing solar does not increase your property tax bill, and it is one of the more misunderstood parts of the code.
The provision
Under 35 ILCS 200/10-5 and following, a solar energy system is valued for assessment purposes at the value of a conventional energy system — not at the cost or value of the solar installation.
In practice this means the panels themselves add little or nothing to your assessment, even though they may add real value to the property in the market.
It is not automatic
This is the part that catches people. The treatment must be claimed — an application to the local assessor, generally in the year the system is installed.
Install without claiming and the system may be picked up as an improvement in the ordinary way, particularly if a permit was pulled, and you will be assessed on value the statute says you should not be.
What it covers
- Photovoltaic panels and their mounting
- Inverters and associated equipment
- Solar thermal systems for water or space heating
Battery storage is a newer question and treatment can vary — worth asking your assessor directly rather than assuming it follows the panels.
Roof-mounted against ground-mounted
Roof-mounted residential systems are the straightforward case. Ground-mounted arrays, particularly large ones, raise questions about whether the land use has changed — and a substantial ground array on agricultural land can affect its use-value assessment. That is a different and more technical conversation.
Leased systems and power purchase agreements
Where the system is owned by a third party under a lease or PPA, the ownership and assessment position differs from an owned system. Ask before signing, because the answer affects who is assessed on what.
The wider point about improvements
Solar is one of several improvements with specific treatment. The home improvement exemption shelters the added value of a general improvement — an addition, a finished basement — for four years from completion, up to a statutory limit.
Both require the same discipline: pull the permit, keep the completion date, and check the assessment the following year to confirm the relief was actually applied. Neither happens because you were entitled to it.
What to do
- Before installing, ask your assessor what they require and when.
- Pull the permit.
- File the claim in the installation year.
- Check the next assessment to confirm the treatment was applied — and raise it if it was not.
Selling a house with solar
The special assessment treatment attaches to the system, but a new owner should confirm with the assessor that it continues rather than assuming. Where the system is leased or under a power purchase agreement, the assignment of that contract is a separate matter from the assessment and is worth resolving before closing rather than after.
For a buyer, two questions: is the system owned or leased, and has the assessment treatment been claimed and applied? The answers are on the assessment record and in the seller's paperwork, and neither is difficult to check.