What Permits and Inspections Do You Need for Solar in Connecticut?

A residential solar installation in Connecticut requires three distinct approvals before your system can legally generate power: a town building permit, an electrical permit, and utility interconnection approval from Eversource or United Illuminating. Each has its own application, timeline, and inspection step. Here is exactly what the process looks like and who handles each piece.

The Three Approvals You Need

Who Handles Each Step

West Electric manages the full permit-to-PTO process on every installation:

• We design the system to meet your town's building department requirements (structural drawings, load calculations, code compliance)
• We file both the building permit and electrical permit applications
• We coordinate inspection scheduling with your town's building and electrical inspectors
• We submit the interconnection application to Eversource or United Illuminating
• We coordinate the utility witness inspection if required
• We notify you when Permission to Operate is received and the system can be activated

You do not deal with the utility or the town permit office directly. We handle it.

Timeline: How Long Does the Full Process Take?

Connecticut residential solar permitting timelines vary significantly by town. Here is a realistic range:

What Goes Into the Town Permit Application

Connecticut towns typically require the following in a residential solar permit package:

• Site plan showing panel layout on your roof
• Electrical single-line diagram
• Structural engineering calculations or a stamped letter confirming your roof framing can support the panel weight
• Equipment specifications (panel datasheet, inverter datasheet)
• Contractor license information (West Electric ELC.0197545-E1 + HIC #0671418)
• Homeowner authorization

West Electric prepares the full permit package. Our design team produces the site plan and single-line diagram; we work with a licensed structural engineer for roofs that require a stamped letter.

Utility Interconnection: Eversource vs. United Illuminating

The utility interconnection process differs slightly between Connecticut's two main utilities:

• Eversource: Uses an online application portal (EAP). Standard residential systems (under 25 kW) go through the simplified review track. Eversource may require a utility witness inspection for systems above a certain size threshold, which adds scheduling time.
• United Illuminating: Similar process, phone-accessible for issue resolution. UI customers in the New Haven service area often experience slightly shorter interconnection timelines for standard residential systems.

Both utilities are required under Connecticut law to process standard residential interconnection applications within 30 business days of receiving a complete application. In practice, complete applications that pass technical review are often approved faster.

Common Reasons for Permit Delays

• Incomplete application: Missing a structural letter or an incomplete single-line diagram is the most common cause of permit rejection. West Electric's design team has a permit rejection rate below 5% on initial submissions.
• HOA or historic district review: If your property is in an HOA or a locally designated historic district, additional approvals may be required before the town building permit is issued. We identify this during the design phase and account for it in your timeline estimate.
• Older electrical service: If the inspector finds code violations in your existing electrical system during the inspection of new solar work, those may need to be corrected before the permit closes.