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NuWatt designs, installs, and manages solar, battery, heat pump, and EV charger systems across 9 states. One company, one warranty, one point of contact.
Get a Free QuoteThe installation itself takes 1–3 days. The full process — from signing your contract to receiving Permission to Operate — typically takes 2.5 to 3.5 months. Here is exactly what happens at each step and what can speed it up or slow it down.
A NuWatt energy advisor visits your property to assess roof condition, shading, electrical panel, and structural suitability. A remote satellite analysis often precedes the site visit. System design is finalized, including panel layout, inverter selection, and single-line electrical diagram.
You sign the installation contract and select your financing (cash, Smart-E Loan through CT Green Bank, or other solar loan). Your installer prepares permit drawings and engineering stamp (required by most CT towns for structural review). Permit applications are submitted to your town building department.
Town building and electrical permits are reviewed and issued. Fast towns (Stamford, Greenwich, New Haven) may permit in 5–10 business days. Average CT towns take 2–3 weeks. Rural or less experienced towns may take 3–4 weeks. Historic district review, if required, adds 4–8 more weeks.
Simultaneously with permitting, your installer submits an interconnection application to Eversource or UI. For most residential systems under 25 kW, this is a Level 1 simplified review. Eversource typically responds within 3–5 weeks; UI within 4–8 weeks. You cannot receive RRES credits until interconnection is approved.
Once permits and interconnection approval are in hand, installation is scheduled. The physical work — mounting racking, installing panels, running conduit, mounting inverter, and connecting to your electrical panel — typically takes 1 day for smaller systems and up to 3 days for larger or more complex installations.
After installation, your installer requests a municipal inspection. The building inspector (and electrical inspector in some towns) verifies the work matches the permitted drawings. Most CT towns complete this within 3–7 business days of request. Your installer schedules and manages this process.
With the town inspection passed, your installer requests the utility PTO inspection. Eversource or UI sends a technician to verify the interconnection meets their requirements. After passing, the utility issues Permission to Operate — typically within 1–2 weeks of the PTO inspection request. Your system is now fully active and earning RRES credits.
Total typical timeline: 10–14 weeks (2.5–3.5 months) from signed contract to PTO. Utility interconnection — especially with UI — is the longest and least predictable variable.
Connecticut has 169 municipalities, each with its own permitting process. Here is a sample of known solar permitting speeds across the state:
| Town | Speed | Typical Time | Notes |
|---|---|---|---|
| Stamford | Fast | 5–10 days | Online portal, experienced staff, solar-friendly |
| Greenwich | Fast | 5–10 days | Efficient process, familiar with solar applications |
| New Haven | Fast | 7–14 days | Online portal, dedicated green building staff |
| Hartford | Moderate | 10–21 days | Standard process, some historic district overlays |
| Bridgeport | Moderate | 10–21 days | UI territory; moderate permit volume |
| Waterbury | Moderate | 14–21 days | Growing solar adoption, standard timeline |
| Glastonbury | Moderate | 10–18 days | Suburban, typically straightforward |
| Simsbury | Moderate | 10–18 days | Residential focus, some historic areas |
| Litchfield | Slower | 21–35 days | Historic district review common, lower volume |
| Essex | Slower | 21–35 days | Significant historic district — can require commission review |
Timelines are estimates based on recent installer experience. Actual times vary by application complexity and current department workload.
Online application portal. Level 1 simplified review for residential systems under 25 kW. Eversource generally responds faster than UI and has invested in process automation.
Pro tip: Submit interconnection app the same day as permit — parallel processing saves 3–4 weeks.
Separate application process from Eversource. UI has historically had longer review times, particularly during peak season (spring–summer). UI is in the process of system upgrades.
Pro tip: UI territory? Allow extra time in your project schedule. Spring installs: start permit + IC app as early as possible.
If your site assessment reveals roof issues — damaged shingles, soft decking, aging flashing — you'll need roofing work before solar can be installed. Most installers can refer roofers, but this adds time.
Many older CT homes (pre-1990) need a panel upgrade before solar can be safely interconnected. Panel upgrades require their own permit and utility coordination. Roll it into your Smart-E Loan at 0.99% APR.
Significant shading from trees often requires removal before solar makes financial sense. Tree removal permitting varies by town — some towns require permits for trees over 10 inches in diameter.
If your home is in a historic district and the commission has jurisdiction over solar, their review meetings are typically monthly. Missing a meeting cycle adds 4–6 weeks. Consider ground-mount to sidestep review.
Ground-mount arrays within 100 feet of inland wetlands require IWC approval, which follows a separate public notice and hearing process. This is a common delay for ground-mount systems on rural CT properties.
Spring and early summer are the busiest times for solar installs in CT. Utilities process more interconnection applications, and timelines can stretch. Starting in winter often means faster processing.
Connecticut passed HB 5036 to modernize solar permitting statewide. The law directs DEEP and PURA to develop a unified online permit portal and standardized review requirements for all 169 municipalities. Implementation is targeted for 2027–2028.
Until HB 5036 is implemented, permitting speed remains town-dependent. NuWatt tracks current permit timelines across CT and factors them into your project schedule.
The permitting and interconnection process involves multiple government agencies and the utility. Here is what a full-service installer like NuWatt manages on your behalf:
NuWatt handles every step from site assessment to PTO. We manage permits, utility interconnection, town inspections, and RRES enrollment — so you can focus on the savings, not the paperwork.