Wisconsin Solar Property Tax Exemption Explained

Wisconsin's solar property tax exemption shields residential and commercial property owners from the increased assessed value that a solar energy system adds to their property. This page covers the statutory basis of that exemption, how assessors apply it, which system configurations qualify, and where the boundaries of coverage lie. Understanding these mechanics matters because without the exemption, a solar installation that raises a home's market value could trigger higher annual property tax bills, undermining the financial case for going solar.

Definition and scope

Wisconsin Statute § 70.111(18) (Wisconsin Legislature) exempts solar and wind energy systems from property taxation. Specifically, the added value that a qualifying solar energy system contributes to a property's assessed value is excluded from the tax base. The exemption applies statewide, meaning every Wisconsin municipality — from Milwaukee County to rural Burnett County — must honor it when assessing properties that carry solar installations.

The statute covers both real property and personal property classifications. A rooftop photovoltaic array installed on a residential home, a ground-mounted system on a farm, and a solar thermal collector used for space or water heating can each fall within scope. The exemption is not capped by a dollar amount; the full incremental value added by the qualifying system is excluded.

Scope and coverage limitations: This page addresses Wisconsin state law only. Federal tax treatment of solar assets — including depreciation and the Investment Tax Credit — operates under separate Internal Revenue Code provisions and is not covered here. Local zoning ordinances that may restrict system placement do not affect the property tax exemption status but fall under a different regulatory framework. Properties located on tribal lands in Wisconsin may be subject to distinct sovereign tax rules outside the scope of § 70.111(18). The exemption also does not address solar sales tax exemption Wisconsin treatment, which is governed by a separate provision of Wisconsin tax law.

How it works

When a property is reassessed after a solar installation, the Wisconsin Department of Revenue's guidance directs local assessors to determine the property's value with and without the solar system. The value attributable to the system is then excluded from the taxable assessment. This process applies annually — the exemption does not require a one-time filing; it persists as long as the qualifying system is in place and Wisconsin law remains unchanged.

The mechanism follows three discrete phases:

1. Installation and permit closure. After a solar system receives its final inspection and interconnection approval, the installation is a matter of record. Permitting concepts relevant to this stage are detailed in the permitting and inspection concepts for Wisconsin solar energy systems reference.
2. Assessor notification. Property owners or their contractors typically notify the local assessor's office of the installation. Some municipalities identify new interconnection agreements through utility reporting.
3. Assessment adjustment. The assessor calculates the contributory value of the solar system — using cost, income, or sales comparison approaches — and removes that increment from the taxable assessed value before setting the annual tax bill.

The Wisconsin Department of Revenue (WI DOR) publishes guidance for assessors on valuing solar installations consistently across the state.

Common scenarios

Residential rooftop system: A homeowner in Dane County installs a 9-kilowatt rooftop photovoltaic system. An appraiser estimates the system adds $18,000 to the property's market value. Under § 70.111(18), the assessor subtracts $18,000 from the assessed value used for property tax calculation. The homeowner's tax bill is calculated as if the solar system does not exist.

Agricultural ground-mount: A farm in Marathon County installs a 50-kilowatt ground-mounted array to offset grain-drying energy loads. Agricultural solar configurations are discussed further at agricultural solar in Wisconsin. The ground-mounted system qualifies for the same statutory exemption as a rooftop installation, provided it meets the definition of a solar energy system under state law.

Leased system: When a property owner finances solar through a lease rather than an outright purchase, ownership of the equipment may rest with a third-party lessor. In that configuration, the equipment may be assessed as personal property of the lessor rather than real property of the homeowner. The tax exemption treatment in lease scenarios can differ from owner-installed systems and warrants direct confirmation with the local assessor. Solar lease vs purchase in Wisconsin covers ownership structure differences in greater depth.

Solar-plus-storage: A battery storage system paired with solar is a distinct asset. The property tax exemption under § 70.111(18) applies specifically to solar and wind energy systems; whether a paired battery qualifies depends on how the assessor classifies the storage component. Solar battery storage in Wisconsin addresses the technical distinctions between integrated and standalone battery configurations.

Decision boundaries

The property tax exemption and the separate federal solar tax credit for Wisconsin residents operate independently. Claiming one does not affect eligibility for the other. However, assessors and property owners should distinguish between the property tax exemption and income tax credits — conflating the two is a common source of confusion.

A critical boundary: the exemption applies to the solar energy system's added value, not to the entire property. If a property is renovated at the same time as a solar installation and that renovation independently raises the assessed value, the non-solar portion of the value increase remains taxable.

Systems that generate power primarily for sale at utility scale — rather than for on-site consumption or net metering — may be classified differently for assessment purposes. Net metering in Wisconsin outlines the distinction between grid-export and self-consumption configurations that can affect how assessors categorize a system's primary use.

For a broader orientation to Wisconsin solar policy and incentive structures, the Wisconsin solar incentives and rebates resource and the regulatory context for Wisconsin solar energy systems page provide complementary frameworks. A conceptual grounding in how photovoltaic systems operate is available at how Wisconsin solar energy systems work, and the full scope of Wisconsin solar resources is indexed at the Wisconsin Solar Authority home.

References

• Wisconsin Statute § 70.111(18) — Solar and Wind Energy Systems Exemption
• Wisconsin Department of Revenue — Solar Energy System Assessment FAQ
• Wisconsin Department of Revenue — Property Assessment Manual
• Wisconsin Legislature — Chapter 70, Property Subject to General Property Taxes
• U.S. Department of Energy — State Solar Policy Database (DSIRE)