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Get a Free QuoteConnecticut has the best TOU spread in New England. Eversource Rate 7 offers a $0.23/kWh peak-to-off-peak spread, and the ESS program pays up to $16,000 upfront plus $225/kW/year in demand response. With the federal ITC dead for homeowners, these programs are how CT batteries actually pay for themselves.
$0.23
Best TOU Spread (Eversource)
$16K
Max ESS Upfront
$225/kW
ESS DR (Yrs 1-5)
$0 ITC
25D Expired
A 13.5 kWh battery (Tesla Powerwall 3) in Eversource CT territory can generate $3,852/year in combined value from TOU arbitrage, ESS demand response payments, self-consumption savings, and RRES adjustment offsets. With the ESS upfront incentive of $3,375, the 10-year total value reaches $36,427.5. In UI territory, the same battery generates $3,892/year with a 10-year total of $36,827.5. Connecticut has the best TOU arbitrage opportunity in New England.
Eversource Annual
$3,852
UI Annual
$3,892
ESS Upfront
$3,375
10-Year (Eversource)
$36,427.5
The federal residential solar tax credit (Section 25D) expired December 31, 2025. Connecticut homeowners now pay full price for batteries with no federal tax break. But CT has something most states do not: the ESS program and aggressive TOU spreads.
While homeowners get $0 in federal tax credits, third-party financing companies can still claim the Section 48/48E commercial ITC (30%) on projects beginning construction before July 4, 2026. The third-party system owner (financing company) claims the ITC — not the homeowner or installer. This makes PPA and lease agreements more attractive because the financing company passes their ITC savings to you as a lower electricity rate.
Eversource CT serves approximately 70% of Connecticut residential customers across Hartford, central, north, and eastern CT. Their Rate 7 (Time-of-Day) tariff has the widest peak-to-off-peak spread in all of New England — making it the single best utility territory for battery arbitrage north of New York.
Eversource Connecticut — Hartford, central, north, and east CT
Peak
Mon-Fri, 12:00 PM – 8:00 PM
$0.307/kWh
Off-Peak
Mon-Fri 8 PM–12 PM, All day Sat & Sun
$0.272/kWh
Flat Rate
Standard service
$0.281/kWh
Peak-to-Off-Peak Spread
$0.035
per kWh
* Rates are all-in (supply + delivery). Jan-Jun 2026 filing. TOU requires 1-year commitment. Eversource installs TOU meter at no cost.
United Illuminating (UI) serves approximately 30% of Connecticut customers in New Haven, Bridgeport, and southwest CT. Their Rate RT (Time-of-Day) offers a narrower but still valuable TOU spread. UI territory includes several economically distressed municipalities that qualify for enhanced ESS incentives.
United Illuminating — New Haven, Bridgeport, southwest CT
Peak
Mon-Fri, 12:00 PM – 8:00 PM
$0.318/kWh
Off-Peak
Mon-Fri 8 PM–12 PM, All day Sat & Sun
$0.283/kWh
Flat Rate
Standard service
$0.292/kWh
Peak-to-Off-Peak Spread
$0.035
per kWh
UI Underserved Community Bonus
New Haven and Bridgeport qualify for the ESS underserved tier ($450/kWh vs standard $250/kWh) — nearly doubling the upfront incentive.
Connecticut replaced ConnectedSolutions (closed December 1, 2023) with the Energy Storage Solutions (ESS) program — and it is significantly more generous. ESS combines upfront incentives with ongoing demand response payments, creating the strongest battery value proposition in New England.
Administered by EnergizeCT / CT Green Bank. Solar pairing is NOT required — standalone batteries qualify.
| Tier | $/kWh | 13.5 kWh Battery | Max Incentive | Max % of Cost |
|---|---|---|---|---|
| Standard | $250 | $3,375 | $16,000 | 50% |
| Underserved Community | $450 | $6,075 | $16,000 | 50% |
| Low-Income | $600 | $8,100 | $16,000 | 50% |
| Period | Summer ($/kW) | Winter ($/kW) | Total ($/kW/yr) | 11.5 kW Battery |
|---|---|---|---|---|
| Years 1–5 | $200 | $25 | $225 | $2,587.5/yr |
| Years 6–10 | $115 | $15 | $130 | $1,495/yr |
3:00 PM – 8:00 PM (June–August, excl. weekends/holidays)
30–60 events per season
5:00 PM – 7:00 PM (December–February, limited events)
1–5 events per season
Discharge requirement: 80% of usable capacity during pre-scheduled events. Your backup reserve (20-30%) is never touched during DR events.
The real power of a CT battery is stacking multiple revenue streams. No single stream justifies the cost — but combined, they create one of the strongest battery value propositions in the country.
ESS Upfront
$3,375
10-Year Total
$36,427.5
ESS Upfront
$3,375
10-Year Total
$36,827.5
The 8-hour peak window (12 PM - 8 PM) in CT means your battery needs enough capacity to discharge throughout the entire peak period. Here is how different battery sizes perform in each utility territory.
| Battery Size | Example | Eversource Annual | UI Annual | ESS Upfront | 5-Year Total (Ev.) |
|---|---|---|---|---|---|
| 5 kW / 5 kWh | Enphase IQ 5P | $1,668/yr | $1,685/yr | $1,250 | $9,590 |
| 10 kW / 10 kWh | Enphase IQ 10T | $3,336/yr | $3,371/yr | $2,500 | $19,180 |
| 11.5 kW / 13.5 kWh | Tesla Powerwall 3 | $3,852/yr | $3,892/yr | $3,375 | $22,632.5 |
Values include TOU arbitrage, ESS DR payments, self-consumption savings, and RRES adjustment offset. ESS upfront incentive uses standard tier ($250/kWh). Underserved/low-income tiers earn more.
These batteries are approved for the CT ESS program. All support demand response dispatch and qualify for upfront incentives.
Most popular, integrated inverter
ESS upfront: $3,375
AC-coupled, legacy model
ESS upfront: $3,375
Modular, pairs with Enphase microinverters
ESS upfront: $1,250
Larger Enphase option
ESS upfront: $2,520
DC-coupled, SolarEdge ecosystem
ESS upfront: $2,425
Whole-home backup capable
ESS upfront: $3,400
Scalable 3–18 kWh
ESS upfront: $2,250
Premium smart home integration
ESS upfront: $3,000
Month-by-month TOU arbitrage estimates for a 13.5 kWh battery at 85% round-trip efficiency. Both utilities use the same peak window (12 PM - 8 PM weekdays), so the difference is purely in rate spread.
| Month | Weekdays | Eversource Arb. | UI Arb. | Note |
|---|---|---|---|---|
| January | 22 | $89 | $72 | Winter off-peak |
| February | 20 | $81 | $65 | Shortest month |
| March | 21 | $85 | $69 | Transition |
| April | 22 | $89 | $72 | Spring rates |
| May | 22 | $89 | $72 | Pre-summer |
| June | 22 | $89 | $72 | Summer begins |
| July | 22 | $89 | $72 | Peak summer |
| August | 22 | $89 | $72 | Peak summer |
| September | 21 | $85 | $69 | Late summer |
| October | 23 | $93 | $75 | Fall rates |
| November | 21 | $85 | $69 | Winter prep |
| December | 22 | $89 | $72 | Winter off-peak |
| Annual Total | 260 | $1,052 | $851 | TOU arb. only |
Arbitrage = usable kWh x spread x weekdays x 85% RTE. Does not include ESS DR payments, self-consumption, or RRES offset — those are additional. Summer rates may differ from winter filings.
Side-by-side comparison of the two CT utilities for solar + battery strategy.
| Feature | Eversource CT | United Illuminating |
|---|---|---|
| Territory | Hartford, central, north, and east CT | New Haven, Bridgeport, southwest CT |
| Coverage | ~70% of CT | ~30% of CT |
| TOU Rate | Rate 7 (Time-of-Day) | Rate RT (Time-of-Day) |
| Peak Rate (all-in) | $0.307/kWh | $0.318/kWh |
| Off-Peak Rate (all-in) | $0.272/kWh | $0.283/kWh |
| TOU Spread | $0.035/kWh | $0.035/kWh |
| Flat Rate | $0.281/kWh | $0.292/kWh |
| Peak Hours | Mon-Fri, 12:00 PM – 8:00 PM | Mon-Fri, 12:00 PM – 8:00 PM |
| Annual TOU Arb. (13.5 kWh) | ~$1,052 | ~$851 |
| Interconnection | 4-8 weeks | 4-8 weeks |
| RRES Program | Yes (administrator) | Yes (administrator) |
| Battery Verdict | Best in NE | Strong |
CT Green Bank's Smart-E Loan offers one of the lowest interest rates in the country for clean energy financing. The 0.99% APR rate is available for heat pump and energy storage installations through March 31, 2026 — up to $50,000.
Battery may be cash-flow positive from day one depending on utility territory and ESS tier. Smart-E rate for solar installations is 6.99-7.99% (NOT 0.99% — that rate is for heat pumps and batteries only).
Both Eversource and UI follow the same general interconnection timeline for battery storage systems in Connecticut.
File interconnection application with your utility (Eversource or UI). Include battery specs, inverter data, and site plan. Your installer handles this.
Utility reviews application for grid compatibility. May request additional documentation for larger systems or Grid Edge locations.
Apply for ESS incentives through EnergizeCT. Can be done simultaneously with utility interconnection. Pre-approval typically takes 1-2 weeks.
Battery installation by licensed CT electrician. Municipal electrical inspection required. Schedule varies by town.
Utility issues PTO after passing inspection. Your battery is now grid-connected and can begin TOU arbitrage and ESS dispatch.
Request Rate 7 (Eversource) or Rate RT (UI). Eversource installs TOU meter at no cost. One-year minimum commitment.
Total timeline: 4-8 weeks from application to PTO. Faster in towns with established solar/battery permitting processes. Grid Edge locations may receive priority processing.
Common questions about time-of-use rates, ESS incentives, and battery strategy in Connecticut.
Get a custom battery + TOU analysis for your Connecticut home. We will calculate your exact ESS incentive, TOU arbitrage potential, and total revenue stack based on your utility territory and usage.
Smart-E 0.99% APR deadline: March 31, 2026. Section 48/48E TPO deadline: July 4, 2026.