How much deposit can a solar panel installation contractor ask for in Wisconsin?

Wisconsin law caps solar panel installation deposits at 25% of the contract. On a typical $20,378 solar panel installation, the maximum legal deposit is $5,095. The statute is Wisconsin Admin. Code ATCP 110. Any contractor demanding more is in violation of state law — refuse and report to the state contractor licensing board.

Industry standard for solar panel installation: 10%. Long lead time but rebate/incentive-funded. Industry standard: 10% deposit, then milestones at panels-delivered / installed / utility-approved. Most legitimate Wisconsin contractors will follow this norm regardless of whether the state has a statutory cap.

Yes — anything above 25% is illegal in Wisconsin under Wisconsin Admin. Code ATCP 110. File a complaint with the state contractor licensing board, share the written request, and consider it a permanent red flag against that contractor. Reputable contractors know the law.

Best practice in Wisconsin: 10% deposit at contract signing → milestone-based progress payments tied to inspectable phases (rough-in, mid-build, substantial completion) → 5–10% retention held until punchlist + final inspection sign-off. Never pay materials in full upfront; if your contractor goes under, the materials supplier owns those goods, not you. Pay via check or credit card — never wire transfer to a personal account.