TOU Battery Savings
Flip one setting. Save through September.
From June 1 through September 30, Georgia Power's on-peak rate is roughly 13× the overnight rate. If your battery is set to Savings / TOU Mode, it captures that spread automatically every weekday from 2 to 7 PM. If it's still on Self-Consumption, you're leaving money on the table. Summer is when the on-peak spread is widest, but the super off-peak benefit runs year-round — this calculator focuses on the four months when the gap is largest.
On-Peak
M–F · 2–7 PM · Jun–Sep
Off-Peak
All other summer hours
Super Off-Peak
Every day · 11 PM–7 AM
Enphase Battery Setup
- Open the Enphase app
- Tap your system → Battery
- Choose Savings (or "Cost Savings")
- Set peak: Mon–Fri 2:00–7:00 PM
- Confirm reserve SoC for grid outage
Franklin Battery Setup
- Open the Franklin Home Power app
- Tap Settings → Operation Mode
- Choose Time of Use
- Configure peak: Mon–Fri 2:00–7:00 PM, Jun–Sep
- Set super off-peak charging window if enabled
How the math works
Calculations, assumptions, and Georgia Power tariff references
Savings come from the rate spread between Georgia Power's on-peak window and the overnight super off-peak window on the Overnight Advantage plan (formerly Plug-In EV). When your battery is in TOU mode, it reserves capacity through the day and dispatches into the expensive 2–7 PM window — and where permitted by your interconnection agreement, charges from the grid overnight at the cheapest rate.
Assumptions: one full peak-window dispatch per day, 90% round-trip efficiency (typical for Enphase IQ and Franklin aPower LFP chemistry), 87 weekday peak days from June 1 through September 30, 2026 (excludes Labor Day; July 4 falls on a Saturday this year).
What this doesn't include: the value of any solar production stored in the battery and dispatched at peak (additional upside), demand-charge avoidance (not applicable to residential Overnight Advantage), or backup-power value during outages. If your interconnection agreement prohibits grid-charging the battery, your savings come from solar-stored discharge against the peak rate — still substantial, roughly $0.20/kWh per peak day instead of $0.27. Adding battery capacity beyond your home's typical 2–7 PM consumption will not produce proportional additional savings — the calculator assumes one full peak-window dispatch per day, and storage that exceeds the home's actual peak load won't fully dispatch.
*September shows 21 peak days after excluding Labor Day (Sep 7). Rates shown are base energy rates from the Overnight Advantage schedule and exclude riders, fuel cost recovery, and franchise fees, which apply equally regardless of dispatch timing and therefore don't affect the savings calculation.
- TOU-OA-14 · Time of Use – Overnight Advantage tariff (PDF) The schedule this calculator is built around. Defines on-peak, off-peak, and super off-peak windows and base energy rates.
- TOU-FCR-6 · Time of Use Fuel Cost Recovery schedule (PDF) Fuel cost adder applied to all TOU-OA kWh consumption (currently ~4.5¢/kWh). Applies equally to all dispatch timing.
- Overnight Advantage rate plan · Georgia Power Customer-facing overview, enrollment, and current pricing summary.
Have solar but no battery yet?
We'll size the storage to your home, model your usage against the TOU windows, and walk you through pricing and financing options. Installs scheduled in June still capture most of the 2026 peak season.
Already have a battery? More capacity, more savings.
The math above scales linearly — doubling your usable kWh roughly doubles your summer savings, up to the limit of your home's actual peak-window consumption. We can quote an add-on Enphase IQ Battery or Franklin aPower unit sized to your existing system.
This calculator is provided for educational purposes by Better Tomorrow Solar. Savings figures are estimates based on the Georgia Power Overnight Advantage tariff (TOU-OA-14) effective January 2025 and assume one full peak-window battery dispatch per weekday from June 1 through September 30, 2026, at 90% round-trip efficiency.
Eligibility. Savings apply only to customers enrolled in Georgia Power's Overnight Advantage rate plan. Customers on the standard residential schedule must enroll in Overnight Advantage to capture this spread; rate plan selection should be modeled against your full annual consumption profile before switching.
Interconnection. Grid-charging the battery overnight requires interconnection agreement provisions that permit it. If your agreement prohibits grid-charging, savings come from solar-stored discharge only — approximately $0.20 per kWh per peak day instead of $0.27.
Rate changes. Georgia Power adjusts base rates and fuel cost recovery riders periodically through Public Service Commission approval. The rates shown here are subject to change. Contact Georgia Power directly for current pricing.
Battery cycling. Running your battery in Time-of-Use mode adds approximately one full cycle per peak weekday (~87 additional cycles per summer). Enphase IQ and Franklin aPower batteries are warranted well beyond this, but accelerated cycling does affect long-term degradation.
Not financial or tax advice. This estimate is not a substitute for advice from your tax professional, your installer, or Georgia Power. Federal residential clean energy tax credits for battery storage were modified by the One Big Beautiful Bill Act (July 2025); consult your tax advisor regarding the current incentive landscape.