Utilities · Central and Gulf Coast Florida

Duke Energy Florida in 2026: doing solar math on a falling bill

SLWritten by the Solar Learning Lab research desk·Updated August 18, 2026·7 min read

Here is a problem almost no solar calculator handles honestly: what happens to payback when the utility bill goes down on its own. Duke Energy Florida's two million customers, spread across St. Petersburg, Clearwater, Orlando's suburbs, and the Nature Coast, watched their bills fall roughly 25 percent during 2026 as storm charges rolled off. Solar still pencils in Duke territory. But the case for it changed shape this year, and a quote built on a January 2026 bill overstates savings by a quarter.

How Rule 25-6.065 actually works

Florida net metering is not utility generosity, it is administrative law. Rule 25-6.065 binds Duke the same way it binds FPL and Tampa Electric, and the mechanics reward reading the actual text over the marketing page. Each billing cycle, exports offset imports kWh for kWh. Export more than you use, and the difference becomes a credit on next month's bill. Credits accumulate for up to twelve months. Whatever remains at the end of the calendar year is cashed out at the COG-1 as-available energy rate, a wholesale number tied to fuel costs rather than retail rates.

The rule also sets the service standards. Standard interconnection agreements for Tier 1 and Tier 2 systems must be processed within 30 days (90 for Tier 3). The utility must send written interconnection approval within 10 business days of receiving your inspection results, and if a second meter is needed to measure exports, the utility pays for it. Duke cannot invent a monthly solar fee on top; the rule does not permit one for standard residential tiers.

If that framework sounds familiar, it is the same one we walked through for FPL customers, where the numbers differ but the rule is identical. What is different in Duke territory is the denominator: the retail rate your credits are worth just fell by a quarter.

Source: Florida Administrative Code Rule 25-6.065.

Solar math when the bill is falling

Florida homes are heavy users, averaging 1,104 kWh a month in 2024 per EIA data, and the state's average residential rate sat near 15.2 cents in May 2026. Multiply those and Duke territory still generates a real bill for solar to attack. What changed is the trajectory. A system quoted in January against a $180 bill now offsets something closer to $135, and payback stretches accordingly. That is not a reason to skip solar. It is a reason to reject any proposal whose savings table was built before March 2026.

The honest sales pitch in Duke territory sounds like this: retail-rate netting is strong, the rule protects you from junk fees, equipment prices are flat, and the falling bill cuts both ways since storm surcharges can return as fast as they left. A system sized to usage hedges you against the next storm-recovery cycle at a lower entry price than FPL customers saw during the 2025 rate increases. We cover the statewide picture, including what the end of the federal 25D credit did to cash purchases, on the Florida page.

Sources: EIA 2024 residential sales data and EIA average price by state, May 2026.

What we could not verify

As of August 18, 2026: Duke Energy Florida's current RS-1 per-kWh energy charges, because both duke-energy.com tariff documents and the Florida PSC site blocked retrieval; the current COG-1 payout value in cents per kWh; and any Duke-specific battery or solar rebate, which we searched for and did not find. The typical-bill figures above are Duke's own published impacts, not our reconstruction of the tariff. When we can read the rate schedule directly, we will publish the per-kWh detail. Corrections run through our editorial policy.