Time-of-Use Rates and Solar Optimization in Georgia

Time-of-use (TOU) electricity pricing structures charge different rates depending on when electricity is consumed, creating a financial incentive — or penalty — tied directly to the hour of day and day of the week. For Georgia solar customers, TOU rate design determines whether a rooftop or ground-mounted system delivers its maximum economic value or falls short of projections. This page covers how TOU rates function within Georgia's utility landscape, how solar generation and battery storage interact with peak pricing windows, and the practical decision factors that shape system sizing and dispatch strategies.

Definition and scope

Time-of-use rates divide the 24-hour day into service level — typically an on-peak period, an off-peak period, and sometimes a mid-peak or super-off-peak period. Electricity consumed during on-peak hours carries a higher per-kilowatt-hour (kWh) charge, while off-peak consumption is priced below the standard blended rate.

Georgia Power, the state's dominant investor-owned utility regulated by the Georgia Public Service Commission (PSC), offers TOU rate options for residential customers under its Schedule TOU-REP (Time-of-Use Residential with Electric Pricing). The PSC sets and approves all rate structures under the authority granted by O.C.G.A. § 46-2-21 and related provisions of Title 46 of the Georgia Code.

Scope and geographic coverage: This page addresses TOU rate structures as they apply to grid-tied solar installations served by Georgia Power and Georgia's 41 Electric Membership Corporations (EMCs). It does not address federal rate-setting authority, out-of-state utility territory that may border Georgia, or off-grid configurations where retail rate structures are irrelevant. For broader regulatory framing that governs solar energy systems statewide, see the Regulatory Context for Georgia Solar Energy Systems.

Municipal utilities — including those operated by the City of Dalton and the City of Acworth — set their own rate schedules and are not subject to PSC jurisdiction. Their TOU offerings, if any, fall outside the scope of PSC docket review and are governed by local ordinance.

How it works

Under a TOU rate structure, the utility meter records not only total kWh consumption but also the timestamp of that consumption. Billing software then applies the applicable rate — on-peak or off-peak — to each interval. Georgia Power's Schedule TOU-REP defines on-peak hours as 2:00 p.m. to 7:00 p.m. on non-holiday weekdays, with off-peak rates applying all other hours (Georgia Power Rate Schedules, PSC Docket).

Solar panels generate electricity during daylight hours. Peak production typically occurs between 10:00 a.m. and 3:00 p.m., a window that partially overlaps with — but does not fully cover — Georgia Power's defined on-peak window. This timing gap is the central optimization challenge for TOU solar customers.

A five-step breakdown of how TOU interacts with a solar system:

1. Morning ramp-up (6:00–10:00 a.m.): Solar output is low; the home draws off-peak grid power at the lower rate.
2. Peak production (10:00 a.m.–2:00 p.m.): Solar generation typically exceeds household load; excess is exported to the grid under the applicable net metering credit rate.
3. Afternoon overlap (2:00–3:00 p.m.): Solar production begins declining while the on-peak pricing window opens; well-sized systems can still offset on-peak consumption during this window.
4. Critical on-peak exposure (3:00–7:00 p.m.): Solar output drops significantly after 3:00–4:00 p.m. in winter months; households without battery storage draw on-peak grid power at premium rates.
5. Off-peak evening (7:00 p.m. onward): Grid power reverts to the lower off-peak rate; battery systems can discharge stored solar energy during step 4 to avoid this window.

For a deeper explanation of how solar generation and grid interaction function as an integrated system, the How Georgia Solar Energy Systems Works: Conceptual Overview provides foundational context.

Battery storage — most commonly lithium iron phosphate (LFP) chemistries in residential applications — is paired with solar specifically to capture midday surplus and discharge it during the 2:00–7:00 p.m. on-peak window. Safety standards for battery storage systems are governed by UL 9540 (Standard for Energy Storage Systems) and NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems), both referenced by the Georgia State Minimum Standard Fire Code.

Common scenarios

Scenario A — Solar only, no battery (standard TOU exposure): A 7-kilowatt (kW) residential system in Atlanta produces approximately 8,400–9,100 kWh annually based on Georgia's average peak sun hours (NREL PVWatts Calculator). Without storage, the household exports midday surplus for a net metering credit but purchases on-peak power from 3:00–7:00 p.m. at the higher TOU rate. The economic outcome depends directly on the credit rate Georgia Power applies to exported energy versus the on-peak import rate charged — a gap that widened following the PSC's 2019 rate case adjustments.

Scenario B — Solar with battery storage: Adding a 10 kWh battery to the same 7 kW system allows the household to store midday surplus and discharge it during on-peak hours, reducing or eliminating on-peak grid purchases. The financial benefit scales with the spread between the on-peak and off-peak rates; wider spreads produce faster payback on battery cost. For detailed battery system considerations, see Solar Energy Storage and Battery Systems in Georgia.

Scenario C — EMC territory with different TOU windows: Georgia's 41 EMCs — including Cobb EMC, Sawnee EMC, and Snapping Shoals EMC — each publish their own rate schedules through their boards of directors, subject to Georgia EMC cooperative governance rather than PSC oversight. On-peak windows and rate differentials vary significantly across EMCs, requiring site-specific rate schedule review before system design is finalized. Sawnee EMC's TOU structure, for example, defines on-peak periods differently from Georgia Power's Schedule TOU-REP, affecting optimal system sizing calculations.

Solar carport and canopy installations — covered in Solar Carport and Canopy Systems in Georgia — follow the same TOU interaction logic as rooftop systems but may achieve slightly different generation profiles due to tilt angle and orientation differences.

Decision boundaries

The central decision for a solar customer considering TOU enrollment is whether the on-peak/off-peak rate differential, combined with the system's generation profile, produces net savings compared to a standard flat residential rate.

Key comparison — TOU vs. flat rate:

Customers with flexible load — electric vehicle charging that can shift to off-peak hours, for instance — often benefit from TOU without battery storage. Those with fixed evening demand patterns (cooking, HVAC) face higher on-peak exposure without a battery to bridge the generation gap.

Permitting considerations are relevant when adding battery storage: Georgia counties require electrical permits for battery installation, and systems must comply with the National Electrical Code (NEC) Article 706 (Energy Storage Systems) and the adopted edition of the Georgia State Minimum Standard Electrical Code. Inspections by the local authority having jurisdiction (AHJ) are required before commissioning. The Georgia Solar Authority home resource provides orientation to the full range of topics relevant to system planning.

From a return-on-investment standpoint, the payback period for a battery added specifically for TOU optimization depends on the rate spread and daily cycling frequency. The Solar ROI and Payback Period in Georgia page addresses the financial modeling framework applicable to these calculations.

References

• Georgia Public Service Commission (PSC) — state regulatory authority for Georgia Power rate schedules and interconnection rules
• Georgia Power Rate Schedules — PSC Docket Archive — Schedule TOU-REP and supporting rate case documentation
• Georgia EMC (Electric Membership Corporations) — cooperative utility governance and member rate resources
• NREL PVWatts Calculator — National Renewable Energy Laboratory solar production estimation tool
• O.C.G.A. Title 46 — Public Utilities and Public Transportation — statutory authority governing Georgia utility rate regulation
• NFPA 855 — Standard for the Installation of Stationary Energy Storage Systems — fire safety standard referenced by Georgia State Minimum Standard Fire Code
• UL 9540 — Standard for Energy Storage Systems and Equipment — safety certification standard for residential and commercial battery installations
• National Electrical Code (NEC) Article 706