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Is plug-in solar legal in Wisconsin?
No specific law
Wisconsin has no plug-in solar law. Plugging a kit into an outlet falls under your utility's interconnection rules, which usually require approval.
Max system sizeNo capsmallest tier: Category 1 <=20 kW
Electrician / permitPermit and inspectionutility rules apply
Tell the utility?Interconnection applicationtypical fee $150
CertificationUL 1741 inverterrequired by every utility
What this means for you
✓ What you can do
- Apply for interconnection like any small generator (Category 1 <=20 kW), typical fee $150.
- Use portable panels with a power station, never connected to house wiring, with no permission at all.
- Install conventional rooftop or ground-mount solar through the standard interconnection process.
✕ Not yet / not allowed
- Plug a grid-tied kit into an outlet without an interconnection agreement; it can breach your service terms.
- Expect a permit or wiring exemption; none exists without a law.
- Count on a law soon: no plug-in solar bill has been filed.
What the rules say
No plug-in solar law or bill in Wisconsin.
No law doesn't mean no rules. In Wisconsin, a kit that pushes power back into your home wiring is treated like any other grid-connected generator. Most utilities require an interconnection application, and plugging in without one can breach your service agreement. Off-grid use (panels charging a battery that powers devices directly) avoids this entirely.
Before you plug in: Wisconsin checklist
- The rule that applies is Public Service Commission of Wisconsin's interconnection process: Wis. Admin. Code ch. PSC 119 (rev. 2024).
- A plug-in kit falls in the smallest tier (Category 1 <=20 kW). $150 (1-8 kW) at MGE; We Energies not retrieved.
- Permits: 2023 NEC (SPS 316, 9/1/2026); DSPS licensing; homeowner exemption.
- Only consider kits with a UL 1741-listed inverter (UL 3700 preferred); a non-listed inverter will not be approved anywhere.
- What exports are worth: Utility parallel-generation/net-metering tariffs (varies).
- If approval is slow or costly, a portable panel and power station (never connected to house wiring) needs no permission.
- No plug-in solar bill has been filed yet; the nearby states that passed laws in 2026 are the template to expect.
The rules in detail
Wisconsin has no statute specific to plug-in solar. Average residential electricity price: 19.06¢ per kWh (EIA, July 2026).
Your utility's rules in Wisconsin
No utility in Wisconsin publishes a rule that specifically allows or bans outlet-connected generation, so the general interconnection agreement is what applies. Here is what the largest residential utilities say and require.
| Utility | Residential customers | Published position on plug-in kits |
|---|---|---|
| We Energies | 1,048,148 | No specific statement. |
| Wisconsin Power & Light (Alliant) | 437,211 | No specific statement; 'All applications must be signed by you and by us prior to commencing parallel generation.'. source |
| Wisconsin Public Service | 411,775 | No specific statement. |
| Madison Gas & Electric | 147,501 | No specific statement; Category 1 fees $150 (1-8 kW) / $300 (9-20 kW). source |
Interconnection terms for a sub-1.2 kW system
| Regulator | Public Service Commission of Wisconsin. |
|---|---|
| Governing rule | Wis. Admin. Code ch. PSC 119 (rev. 2024). |
| Smallest tier | Category 1 <=20 kW. |
| Application fee | $150 (1-8 kW) at MGE; We Energies not retrieved. |
| Electrician / permit | 2023 NEC (SPS 316, 9/1/2026); DSPS licensing; homeowner exemption. |
| Export compensation | Utility parallel-generation/net-metering tariffs (varies). |
| Electrical code | 2023 NEC (eff. 9/1/2026). |
In practice
- High fixed Category 1 fee.
- Sales-tax exemption may apply to kits; only 2023 NEC.
State incentives
- Focus on Energy rebate (Trade Ally required).
- Sales-tax exemption Wis. Stat. 77.54(56).
Who is pushing for a law
- RENEW Wisconsin
- Clean Wisconsin
- Sierra Club WI
Savings preview: 800 W kit in Wisconsin
Adjust for your setup →≈ $156/year
Frequently asked questions
Is plug-in solar legal in Wisconsin?
Wisconsin has no plug-in solar law. Plugging a kit into an outlet falls under your utility's interconnection rules, which usually require approval.
Do I need a permit or electrician for plug-in solar in Wisconsin?
Default. Check with your local building department before you plug in.
Do I have to tell my utility in Wisconsin?
Default. Plugging in a grid-tied kit without following this can breach your service agreement.
What can an 800 W plug-in kit save in Wisconsin?
Roughly 819 kWh and about $156 per year at Wisconsin's average residential rate of 19.06¢/kWh, assuming a typical balcony or patio mount. See the calculator for your exact setup.