THE SHORT ANSWER
An array expansion is a change to one interconnected system, not a stand-alone count of new panels. Reconstruct the accepted existing design, show the combined equipment and unrounded ratings, and ask Duke Energy Florida and the actual permitting authority which current review path applies before work begins. Duke’s published Tier 1 and Tier 2 bands are useful starting points, not a classification shortcut. [1][2]
Reconstruct the existing system before designing the addition
Start with the current Duke account and the system that is already connected to it. Collect the original interconnection reference, final equipment schedule, one-line or as-built drawing, permit number and closeout, completion or meter communications, monitoring platform and any later service or equipment changes. Copy exact module, inverter, storage, gateway and disconnect models from reliable records. Do not assume the original sales proposal is the final installed design.
Create three evidence columns: approved record, safely observable installed record and unresolved difference. A homeowner should not open an electrical enclosure or climb onto a roof to complete this inventory. Use dated photographs already in the owner file or have a qualified provider document accessible labels. If records are missing, say not provided rather than rebuilding an approval from memory. The expansion design needs a defensible baseline before it can describe what changes.
Show existing, added and combined values separately
Build a capacity worksheet with separate rows for existing modules and inverters, proposed additions, storage equipment and the combined system. Keep module DC nameplate, inverter AC output, battery power, battery energy and annual production in different fields. Ask the responsible designer which value and method Duke uses for the actual configuration; do not choose whichever number produces a preferred tier.
Hypothetical example: an existing array has 18 modules rated 400 W each and the proposal adds 8 modules rated 425 W each. The module nameplate rows are 7.2 kW DC and 3.4 kW DC, for 10.6 kW DC combined. That arithmetic alone does not select a Duke tier because the applicable rating basis and complete equipment configuration still require confirmation. Preserve the unrounded inputs, inverter limits and Duke response. The example teaches transparent arithmetic; it does not classify or approve a real project.
Reconcile the expansion with the physical property
An available-looking roof rectangle does not establish a buildable expansion. Ask the project team to review roof age and condition, attachment zones, access and setback paths, shade, structural assumptions, module dimensions, existing array layout, conductor and overcurrent protection, inverter input limits, service equipment and the point of interconnection. Identify any battery, generator or other power source that shares equipment.
Use one revised site plan and one-line to show both the existing and proposed system. If the addition uses a different module or inverter family, document electrical and physical compatibility rather than calling it equivalent. If roof work, a service upgrade or equipment relocation is outside the solar price, label the exclusion and responsible party. The project record should make the change visible to a reviewer without forcing them to compare two unrelated drawings.
Ask both authorities about the current change path
Duke’s current pages separate Tier 1 projects of 10 kW or less from Tier 2 projects larger than 10 kW and under 100 kW. [1][2] Florida’s rule provides the statewide interconnection framework, while Duke’s current forms and account-specific review govern the utility submission. [3] The city in a mailing address may not be the permitting authority, so identify the jurisdiction for the exact parcel and ask it what revised permit or plan review applies.
Record each answer with the date, contact channel, reference and design version discussed. Submitted is not accepted, and an original permission-to-operate record does not automatically approve added equipment. Likewise, a local permit decision does not issue Duke authorization. Keep utility and jurisdiction milestones in separate lanes and identify which party owns the next correction. Do not order equipment or schedule field work around an assumed answer.
Close out one complete expanded-system record
After authorized work, reconcile the installed module count, inverter and storage models, one-line, permit inspection result, Duke completion record, meter or authorization communication, monitoring configuration and warranties. Mark superseded records without deleting them. The owner packet should explain which equipment is original, which was added and which accepted document describes the complete system.
Update the production model and proposal comparison using the final design. Added panels should change capacity, modeled production and offset assumptions rather than leaving an older percentage in place. Keep modeled energy separate from a guaranteed bill result. Origin Direct can review the combined design and produce a property-specific scope after verification; it cannot guarantee tier treatment, approval timing, a five-year payback, a zero bill or future savings.
Before your next conversation
- Collect the final existing-system and Duke records.
- Show existing, proposed and combined ratings without rounding away a boundary.
- Put the complete system on one site plan and one-line.
- Track local permit and Duke decisions separately.
- Close out one installed and approved expanded-system file.
Primary sources
- Duke Energy: Net Metering Tier 1 Interconnection Process
Checked October 22, 2026. Duke currently labels Tier 1 as projects 10 kW and less. Confirm the applicable Duke Energy Florida process, rating basis and current documents for the complete existing-plus-proposed design.
- Duke Energy: Net Metering Tier 2 Interconnection Process
Checked October 22, 2026. Duke currently labels Tier 2 as projects larger than 10 kW and under 100 kW. Confirm current insurance, application and project requirements directly for the complete design and account.
- Florida Administrative Code Rule 25-6.065: Interconnection and Metering of Customer-Owned Renewable Generation
Checked October 22, 2026. Florida Department of State identifies this as the latest final adopted version. Utility forms, tariffs, local permits and project-specific review still control the actual work and submission.
Planning examples and questions are Origin’s editorial guidance, not a property-specific diagnosis, engineering design, tax determination or promise of savings. Manufacturer and utility references do not imply an affiliation with Origin.
Make the decision specific to your home.
Request an Origin Direct expansion review with the current Duke bill, existing equipment record and proposed addition. Origin will confirm property coverage and reconcile the complete design before final scope or pricing.
Request an Origin Direct quote →Scope, pricing and availability are confirmed for your property. A request is not a confirmed appointment.