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Connecticut has two investor-owned utilities — and both administer the RRES program identically. Eversource averages $0.29/kWh, UI averages $0.28/kWh. The difference? About $129/yr on an 11 kW system. Here is the full breakdown.
Eversource CT
$0.29/kWh
United Illuminating
$0.28/kWh
Annual Difference
~$129/yr
Federal ITC
$0
Federal Residential Solar Tax Credit (Section 25D) Expired December 31, 2025
Homeowners in both Eversource and UI territory receive $0 in federal tax credits for cash or loan purchases. PPA/lease providers can still claim Section 48/48E (30%) through July 4, 2026. Is solar still worth it without the ITC?
Every metric that matters for solar — compared line by line. Most categories are identical because CT PURA regulates both utilities under the same RRES framework.
| Category | Eversource CT | United Illuminating |
|---|---|---|
| Average Residential Rate | $0.29/kWh | $0.28/kWh |
| Supply Rate (Jan-Jun 2026) | $0.1264/kWh | $0.13695/kWh |
| Service Territory | Hartford, north/east/central CT | New Haven, Bridgeport, SW CT |
| Interconnection Timeline | 4-8 weeks | 4-8 weeks |
| RRES Administration | Yes (regulated by PURA) | Yes (regulated by PURA) |
| Solar Energy Adjustment (2026) | $0.0402/kWh | $0.0402/kWh |
| Minimum Monthly Bill | $7.00 | $7.00 |
| RRES Netting Credit Rate | Retail rate | Retail rate |
| Buy-All Tariff Rate (2026) | $0.3289/kWh (locked 20yr) | $0.3289/kWh (locked 20yr) |
| Sales Tax Exemption | 6.35% (Form CERT-140) | 6.35% (Form CERT-140) |
| Property Tax Exemption | Permanent, 100% | Permanent, 100% |
Bottom line: Out of 11 comparison categories, 9 are identical. The only differences are the total rate ($0.01 gap) and supply rate composition. Your utility does not meaningfully change the solar decision.
Your electric bill has two main components. Understanding the split matters because RRES netting credits offset the full combined rate.
Basic Service rate, changes every 6 months (Jan & Jul)
Distribution + transmission charges. Relatively stable, increases 2-4%/yr.
Standard Offer rate, changes every 6 months (Jan & Jul)
Distribution + transmission charges. Relatively stable, increases 2-4%/yr.
Higher electricity rates mean more value from every kWh your solar system produces. Eversource’s $0.01/kWh premium translates to a modest but real advantage.
Each kWh produced by solar avoids buying electricity at the retail rate. At $0.29/kWh (Eversource), each kWh saves $0.01 more than at $0.28/kWh (UI). On 12,925 kWh/yr, that is $129 more annually.
Under the RRES Netting Tariff, excess solar exported to the grid earns credits at your full retail rate. Higher retail rate means higher credit value per exported kWh — another advantage for Eversource customers.
CT electricity rates have increased 3-5% annually since 2020. Both utilities are trending upward. Solar value grows each year as rates rise — regardless of which utility serves you.
| Year | Eversource CT | United Illuminating |
|---|---|---|
| 2020 | $0.220/kWh | $0.210/kWh |
| 2021 | $0.230/kWh | $0.225/kWh |
| 2022 | $0.255/kWh | $0.250/kWh |
| 2023 | $0.270/kWh | $0.265/kWh |
| 2024 | $0.280/kWh | $0.275/kWh |
| 2025 | $0.285/kWh | $0.278/kWh |
| 2026NOW | $0.290/kWh | $0.280/kWh |
Sources: CT PURA rate filings, EIA state-level residential rates. Rates shown are average all-in residential rates including supply and delivery.
Connecticut’s Public Utilities Regulatory Authority (PURA) sets identical RRES terms for Eversource and United Illuminating. There is zero difference in how the program works.
Same terms whether Eversource or UI administers your account.
Same $0.3289/kWh rate regardless of utility. Set by PURA.
The Solar Energy Adjustment is the biggest cost factor for new 2026 RRES enrollees — and it is identical regardless of your utility.
Both Eversource and United Illuminating follow CT PURA interconnection standards. The process, timeline, and requirements are nearly identical.
Installer submits interconnection application to your utility with system design documents, single-line diagram, and equipment specifications.
Utility engineering team reviews system design for code compliance, transformer capacity, and grid impact. May request modifications for larger systems.
Utility issues conditional approval. Installer schedules installation and municipal inspection.
Town building inspector verifies the installation meets electrical and building codes. Most CT towns process this within 1-2 business days.
Utility installs net meter (or reprograms existing smart meter) and grants PTO. System can now generate and export power.
No interconnection fee for residential solar systems under 25 kW with either utility. Both utilities have online portals for application tracking.
Eversource serves approximately 75% of Connecticut’s residential customers. United Illuminating covers the southwest corner — primarily Fairfield and New Haven counties.
North, east, and central Connecticut. Serves ~1.2 million electric customers statewide.
Plus many smaller towns. Check your bill or call 800-286-2000.
Southwest Connecticut — Fairfield and New Haven counties. Serves ~340,000 electric customers.
Parent company: Avangrid (AVGO). Call 800-722-5584.
The most common CT residential solar system is 11 kW, producing approximately 12,925 kWh/yr. Here is exactly how the numbers compare between utilities.
Eversource customers earn approximately $129/yr more from the same 11 kW system compared to UI customers. Over 25 years, that is roughly $3,200-$4,000 more (with rate escalation).
However, this gap is not large enough to influence your solar decision. You cannot switch utilities — your address determines your provider. Both territories offer strong solar economics with 8-10 year payback periods.
Eversource territory has a slight edge due to the $0.01/kWh higher retail rate, translating to ~$129/yr more value on an 11 kW system. But here is the honest take:
Our recommendation: Whether you are in Eversource or UI territory, solar is a strong investment in Connecticut. Focus on getting competitive installer quotes, choosing the right financing option, and enrolling in RRES before any further rate changes — not on which utility you happen to be in.
Estimate your solar savings for your specific utility, system size, and financing choice. Select Eversource or United Illuminating to see your personalized numbers.
Estimate your solar return on investment with RRES income, CT tax exemptions, and ESS battery incentives.
Federal Residential Solar Tax Credit (Section 25D) Expired
Homeowners who purchase solar with cash or a loan receive $0 in federal tax credits. Section 25D expired December 31, 2025.
Hartford, most of CT (north, east, central)
New 2026 enrollees pay $0.0402/kWh Solar Energy Adjustment on all production
Electric Rate
$0.29/kWh
RRES Program
Netting Tariff
Solar Energy Adj.
$0.0402/kWh
Interconnection
4-8 weeks
Permanent exemption — solar adds $0 to your property tax bill
Payback
7.6
years
25-Year Savings
$133,649
total
Monthly
$323
per month
Estimates based on average 2026 CT solar pricing, RRES netting tariff at retail rate, $0.0402/kWh Solar Energy Adjustment, 6.35% sales tax exemption, permanent property tax exemption (~2.04% effective rate), and ESS incentive at $250/kWh standard tier. Section 25D residential ITC expired Dec 31, 2025 — $0 federal tax credit for cash/loan purchases. CT has no state income tax credit for solar.
Common questions about solar in Eversource vs United Illuminating territory.
Both utilities administer the RRES program identically under CT PURA rules. Eversource has a slightly higher average rate ($0.29/kWh vs $0.28/kWh), which means marginally higher net metering value — about $129/yr more on an 11 kW system. This difference is not significant enough to base a solar decision on. Both utilities have the same Solar Energy Adjustment ($0.0402/kWh), same interconnection timeline (4-8 weeks), and same RRES tariff terms.
Check your electric bill — it will say either "Eversource" or "The United Illuminating Company." Generally, Eversource covers most of Connecticut including Hartford, Stamford, Norwalk, Waterbury, and the north/east/central regions. United Illuminating serves New Haven, Bridgeport, and southwest CT (primarily Fairfield and New Haven counties). You can also call Eversource at 800-286-2000 or UI at 800-722-5584.
No. The Solar Energy Adjustment is set by CT PURA and applies equally to both utilities. For 2026 RRES enrollees, the rate is $0.0402/kWh on ALL solar production — not just exports. On an 11 kW system producing 12,925 kWh/yr, this costs ~$520/yr regardless of your utility. Legacy customers (enrolled before 2026) are grandfathered at $0.005/kWh through December 31, 2039.
Both utilities credit excess solar generation at the full retail rate under the RRES Netting Tariff. Since Eversource has a higher average retail rate ($0.29/kWh vs $0.28/kWh for UI), each exported kWh is worth slightly more in Eversource territory. Credits roll over monthly and are only cashed out if you terminate service.
The process is nearly identical. Both follow CT PURA interconnection standards. Steps include: installer submits application, utility performs technical review, conditional approval issued, municipal inspection, then meter swap and permission to operate. Total timeline is 4-8 weeks for both utilities. Neither utility charges a separate interconnection fee for residential solar systems under 25 kW.
No. Connecticut is not a deregulated market for distribution. Your utility is determined by your physical address — you cannot switch between Eversource and UI. You CAN choose an alternative electric supplier for the supply portion of your bill, but this does not affect your RRES netting credits, which are based on the full retail rate from your assigned utility.
The residential solar tax credit (Section 25D) expired December 31, 2025 under the OBBBA. Homeowners who purchase solar with cash or a loan receive $0 in federal tax credits. However, PPA and lease providers (third-party system owners) can still claim the Section 48/48E commercial ITC at 30% for systems beginning construction before July 4, 2026. This applies the same way regardless of whether you are in Eversource or UI territory.
No. CT tax exemptions are statewide and apply identically regardless of utility. The 6.35% sales tax exemption saves ~$2,005 on a typical 11 kW system. The permanent property tax exemption means solar does not increase your assessed home value for tax purposes — saving ~$644/yr at the state average 2.04% effective rate. There is no state income tax credit for solar in CT.
City-by-city pricing, system sizes, and what is included in your quote.
Complete guide to netting tariff, Buy-All, and the Solar Energy Adjustment.
How RRES netting credits work, credit rollover rules, and legacy grandfathering.
Compare financing options including Smart-E loans and PPA/lease with Section 48 ITC.
Whether you are in Eversource or UI territory, Connecticut’s high electricity rates and RRES program make solar a strong investment. Get a free, no-obligation estimate for your home.