Methodology

Last updated November 1, 2026

Utility rates and export rules

34 Florida utilities have an entry read from the utility's own published residential rate schedule and net-metering or distributed-generation policy, or from the tariff it filed with the Florida Public Service Commission. 27 of 34 rate schedules are read directly from those documents; where a utility does not publish a figure (several cooperatives post no power-cost adjustment, and some municipals do not publish their export credit) the entry carries a labeled estimate and the page says so. Every utility page links the source document, prints the schedule's effective date and the date we last read it, and lists what the utility did not publish. Full review: November 1, 2026, repeated each January when the investor-owned utilities reset their fuel and storm charges and again in spring for the cooperatives. The index is Solar in Florida by utility.

Florida has no single net-metering rule for everyone. The four investor-owned utilities (FPL, Duke, TECO and FPUC) follow Public Service Commission Rule 25-6.065: kilowatt-hours you export offset kilowatt-hours you import within the month, unused credits carry forward for up to twelve months, and whatever remains at the end of the calendar year is paid at the utility's as-available energy cost (we model that payout at 3¢, close to recent years). Municipal and cooperative utilities set their own terms. 12 of the 34 net at retail in some form; the rest credit exports at their own published rates, and some use a dedicated solar schedule. Each rule is applied as written, month by month, so the estimate reflects what your utility actually does.

How the rules enter the estimate: savings are valued at the marginal energy rate for each month (seasonal schedules included, such as Duke's winter rate). A demand charge every customer pays is not counted as savings, because rooftop solar rarely lowers a home's billed peak; a demand charge, surcharge or separate schedule that only solar customers take is subtracted or applied. Surplus production is forfeited or paid out exactly as the policy says. When you upload a bill, the estimate uses the energy price that bill actually paid instead of the schedule, which also corrects for the fuel adjustments that move monthly.

Which utility serves an address

Service territories come from the Homeland Infrastructure Foundation-Level Data “Electric Retail Service Territories” layer (U.S. Department of Homeland Security and Oak Ridge National Laboratory), Florida subset, 2020 vintage. The layer is coarse at town edges and, in a few places, wrong (it has no polygon for Keys Energy or for FPL's Northwest division, and it misses LCEC around Cape Coral), so we add city-level rules for the known cases, and the estimate always lets you confirm or change the utility. Corrections are logged to improve the rules.

Roof and production

Roof planes, pitch, orientation and shading come from Google's Solar API, which covers Florida's metropolitan areas with high-resolution imagery; we fill south-facing planes first (south, southeast, southwest, then east and west) and never due north. Annual production per kilowatt is a Florida reference table for 70 cities built from the European Commission's PVGIS model (version 5.3, ERA5 climatology, 2005 to 2023) at a 30° tilt facing south with 14% system losses, adjusted for your roof's orientation and tilt. There is no snow derate; shading and soiling sit inside the loss figure. Each estimate names its reference city. The production range is ±8%. Hurricane wind loads are a matter for the installer's engineering under the Florida Building Code, not for the production model.

System size

The recommended system offsets 100% of annual use (net zero). Annual use comes from your bill's twelve-month history when you upload one (±5%), otherwise from one month's figure scaled with a Florida load shape: the statewide monthly pattern of residential use from the U.S. Energy Information Administration (2023 to 2025), which peaks in July and August at about 11% of the year each and bottoms in November, adjusted for how your home is heated. Roof area and the utility's size tiers are reported as notes rather than used to shrink the size.

Installed cost

Cash prices before any incentive, from a Florida size ladder (October 2026) anchored on EnergySage's Florida marketplace average ($2.12 per watt at a 13 kW typical quote) and SolarReviews' Florida figure, following the same size curve as our Montana data: $3.05 per watt at 4 kW down to $2.05 at 20 kW and above, with a ±10% range. Systems above 20 kW use the top of the ladder; commercial and ground-mount pricing is not separately modeled yet.

Incentives

Florida exempts solar equipment from sales tax (Florida Statutes 212.08(7)(hh)) and excludes the value a residential system adds from property tax (193.624); the estimate's prices and savings already reflect both, and no separate state credit exists to add. Business-owned systems, including rental property, use the 30% federal investment credit (Section 48E) for systems placed in service by the end of 2027, plus 100% bonus depreciation valued at an assumed combined marginal tax rate; tax-exempt owners receive the 30% as a cash payment (elective pay). Utility rebates and leased or third-party-owned pricing are not modeled. None of this is tax advice.

Savings and payback

First-year savings follow the utility's rule above. Payback is the year cumulative savings pass the installed cost, with electricity prices rising 2.7% a year, an assumption rather than a forecast, and panel output declining 0.5% a year. Where exports earn less than retail, we assume 35% of production is used on site without a battery; in Florida that share is probably higher in summer, when air conditioning runs through the afternoon, so those estimates lean conservative. Headline figures are the best case for the recommended system; the full range is always shown beneath them.

What we do not model

• Time-of-use schedules (CHELCO's solar rate and the optional plans at FPL, Duke and TECO); solar customers on those are estimated on the standard schedule with a note.
• OUC's demand-level charge above the lowest level, and Lakeland's value-of-solar credit beyond the published net demand rate.
• Commercial and institutional rate schedules; non-home estimates use the residential schedule with a note.
• Batteries, financing, leases and loan terms.

Corrections

If a utility changes a rate or we have something wrong, email mtsolarestimate@gmail.com. Corrections go into the same table the estimator and these pages read from, so they take effect everywhere at once.