Add FranklinWH to an Existing Solar System

A FranklinWH aPower 2 can be added to some existing solar systems without replacing the working solar inverter, but the brand name alone does not establish compatibility. The retrofit has to pass an exact-equipment review, place the solar and protected loads correctly around a compatible aGate, coordinate charge and export controls, amend the utility approval when required, and prove grid-loss behavior in commissioning.

This guide covers Teamsun’s verified Connecticut, Massachusetts, and Rhode Island geography. Teamsun publishes a battery retrofit service route, but no verified evidence available for this article establishes FranklinWH authorization, supply, design, commissioning, program enrollment, warranty administration, service capability, labor pricing, or installed results. The service link is a conversation route—not proof that one model or configuration is available or supported.

Direct answer: Start a retrofit quote with the current aPower 2, exact SKU APR-10K15V2-US, because FranklinWH documents it as an AC-coupled battery and markets it for existing-solar retrofits. Do not convert that positioning into a universal approval. Compare it with the aPower S, exact SKU APRS-10K15V1-US, only if a proposal deliberately changes the PV architecture to use direct PV inputs or combines documented aPower S and aPower 2 units. Freeze the existing inverter, aGate generation, one-line, loads, utility settings and warranty responsibilities before comparing those paths.

Can FranklinWH be added without replacing existing solar?

Often, preserving a healthy PV system is the first path worth testing. In an aPower 2 retrofit, the existing string inverter or microinverters continue converting array DC to AC. The aPower 2 charges from the site’s AC system, while the aGate supplies islanding, metering and control functions. That avoids assuming the array must be rewired merely because storage is being added.

FranklinWH calls aPower 2 “inverter agnostic” on its solar-retrofit page. Treat that as product positioning, not approval for every inverter model, firmware, rapid-shutdown arrangement, service layout, export mode or local rule. The installed combination still needs an accepted one-line and qualified design review.

Preservation is not automatically the best path. Rearchitecture deserves a separate quote when the old inverter is failed or nearing a planned replacement, the array is being expanded, direct-PV charging is a documented objective, or the existing control path cannot produce supported islanded behavior. The AC-versus-DC battery guide explains the general architecture tradeoff. This page decides whether one FranklinWH design fits one existing solar system.

Do not use the battery to conceal an unresolved PV fault. Establish a production baseline and close active inverter, ground-fault, arc-fault, roof-leak, ownership or monitoring issues first. A battery installed beside a faulted array does not prove the original system was repaired.

What belongs in the existing-system data room?

A credible proposal should be reproducible by a second qualified designer. Assemble these records before final pricing:

Folder	Evidence to collect	Decision controlled
Utility approval	Permission to Operate, approved one-line/site plan, interconnection agreement, tariff/program enrollment and export setting	What was approved and what modification must be filed
PV equipment	Module count/labels; inverter or microinverter, optimizer, rapid-shutdown and combiner exact models; firmware where relevant	Whether the existing AC source can be retained and controlled
PV design	String map, DC/AC ratings, breakers, conductors, disconnects, grounding and production meters	Tie-in and protected-bus limits; rearchitecture feasibility
Ownership	Cash/loan/lease/PPA agreement, liens, installer/manufacturer/workmanship warranties	Who may authorize alteration and who owns displaced equipment
Operating history	At least 12 months of production, alerts, outages, fault/repair tickets and monitoring access	Healthy baseline and post-work comparison
Service	Meter/main/subpanel photos, ratings and schedules; service conductors; generators or transfer equipment	aGate placement, whole/partial backup, protection and utility scope
Loads	Appliance nameplates, 120/240 V, running and starting demand, daily energy, priority and fallback	Battery quantity, power, reserve and Smart Circuit scope
Site/network	Mounting dimensions, structure, egress, flood/snow/drainage, vehicle exposure, router and cellular conditions	Code, installation, communications and service access

If the one-line or labels are missing, make “field verify and redraw” an explicit predesign task. Do not let a bidder silently assume the inverter model or panel topology. Request one frozen existing-system schedule from every bidder so differences in proposed scope remain visible.

Send the existing-system packet for a retrofit-scope conversation. Ask the returned proposal to name who will verify FranklinWH credentials, engineering, utility filing, commissioning and service rather than treating those handoffs as implied.

How does the aPower 2 versus aPower S gate work?

FranklinWH’s current aPower 2 data sheet and aPower S data sheet describe different conversion boundaries. Do not copy specifications from one into a quote for the other.

Gate	aPower 2 (APR-10K15V2-US)	aPower S (APRS-10K15V1-US)	Evidence required
Coupling	AC-coupled battery	Hybrid-coupled battery with four PV MPPTs	Exact product schedule and one-line
Existing PV	Candidate for retaining a working AC inverter/microinverters	Direct PV implies string, shutdown and solar-conversion redesign	Existing model/listing plus before/after solar scope
Usable energy	15 kWh	15 kWh	Quantity, operating reserve and warranty schedule
Continuous output	10 kW / 11.5 kVA at stated rating boundary	10 kW battery-only; up to 11.5 kW with qualifying PV input	Selected equipment, temperature and operating case
Motor-start headline	15 kW for 10 seconds; 25 kW for 1 second; 185 A LRA under stated conditions	Same published headline boundary	Nameplate/start measurement and concurrent-load test
Solar inputs	None; solar remains an AC source	Up to 20 kW STC direct PV input under four-MPPT limits	Module/string voltage-current and temperature design
Mixed route	Multiple aPower 2 units under a supported aGate design	Data sheet documents parallel AC-coupled aPower 2 support	Released combination design, quantities and firmware

Both data sheets list 120/240-V and 120/208-V operation; that does not mean one design or nameplate value fits every service. The aPower 2 sheet lists up to 15 batteries and 225 kWh per aGate as a manufacturer maximum. Local service, conductor, breaker, utility, space and load constraints may impose a much lower project limit.

The decision is not “newer product wins.” Choose the smallest supported intervention that satisfies the outage and lifecycle goals. Preserve healthy solar when an AC-coupled aPower 2 one-line passes. Consider aPower S when direct PV or planned solar replacement creates a documented benefit worth the extra redesign. Defer when neither path has complete equipment, ownership or utility evidence.

Which aGate generation, one-line, and hardware must the quote name?

The current aGate 1.3/1.3.1 and aPower 2 installation guide identifies aGate X 1.3 and aGate X 1.3.1 as distinct hardware revisions. FranklinWH also publishes a backward-compatibility statement. Require the bidder to apply the current revision table to every battery, aGate, optional module and firmware—not merely write “Franklin gateway.”

One-line item	Proposal must state	Closeout proof
Existing PV	Exact inverter/microinverter, AC rating, breaker, connection point and whether inside backup	Retained-equipment list and before/after production test
Battery	aPower 2 or aPower S exact SKU, quantity, breaker/conductor and wall/floor location	Serial numbers, labels and registration
aGate	Exact aGate generation, service or load-side topology, whole/partial backup boundary	As-built one-line and configuration export
Metering/control	Current-transformer locations/polarity, solar/site/load paths and export control	Commissioning readings reconciled to independent observations
Smart Circuits	Exact compatible module, identified circuits, 120/240-V treatment and control rules	Circuit schedule plus app/manual test
Generator	Exact released generator module, listed generator make/model, breaker, neutral/ground and control path	Approved one-line and witnessed start/stop/charge test
Communications	Wi-Fi/Ethernet path, account owner, installer access, cellular limitations	Owner login, alerts, update and offline/recovery test
Utility	Existing and revised AC ratings, export/non-export mode, tariff/program and meter	Written approval and post-install authorization

FranklinWH’s Smart Circuits page describes an optional module controlling two 120-V circuits and one 240-V circuit. That is not a universal whole-home load-management promise. Confirm compatibility with the quoted aGate, panel wiring, load ratings and owner priorities.

FranklinWH also documents an optional generator integration for supported configurations. Do not infer that a portable generator, vehicle outlet, existing automatic-transfer switch or any generator model may be connected. Generator support is a separate engineered path with exact released hardware, firmware, clearances, fuel/exhaust, grounding, interlock, permit and test requirements.

How should backup power, motor starts, and runtime be sized?

Power controls which loads can run or start together. Energy helps determine duration. The 15-kWh label and 185-A LRA headline answer neither question alone.

Load/circuit	Voltage	Running W/kW	Start A/LRA and seconds	Hours/day	kWh/day	Priority	Control/fallback
Well or sump pump	___	___	___ / ___	___	___	___	___
Heat-pump compressor	___	___	___ / ___	___	___	___	___
Refrigerator/freezer	___	___	___ / ___	___	___	___	___
Medical/safety load	___	___	manufacturer record	___	___	critical	independent plan ___
Range/dryer/EV/hot tub	240 V	___	___	___	___	exclude/control	___
Lighting/network/outlets	120 V	___	___	___	___	___	___
Simultaneous design case	mixed	___	largest start ___	—	___	—	reserve ___%

Review split-phase balance, shared neutrals, motor controls and which panel contains each circuit. “Whole-home backup” can describe the islanding boundary while still requiring automatic or manual load limits. A current data-sheet peak is a laboratory/nameplate boundary, not proof that a specific heat pump and well pump can start together.

A replaceable first-pass duration equation is:

available battery kWh at the selected reserve and temperature ÷ average supported kW = first-pass hours

Then account for conversion and standby loss, cycling limits, changing loads and weather. Add solar recharge only after the exact islanded solar configuration passes. Do not convert a monthly bill into guaranteed outage hours.

What should commissioning prove during grid loss and failure states?

An existing grid-tied PV system ordinarily shuts down when the grid is absent unless supported islanding equipment establishes a local grid and controls the solar source. In an AC-coupled aPower 2 design, the battery and loads must be able to absorb or curtail solar production while islanded. A full battery, light load, inverter setting or communication fault can change solar behavior.

Require this witnessed acceptance sequence:

1. Record grid-connected site, solar, battery and load readings; verify current-transformer direction and export setting.
2. Confirm the app and installer tools show the exact aPower, aGate, PV source, optional modules, serials and firmware.
3. Open the approved grid-isolation path under qualified supervision and verify no backfeed.
4. Run the agreed simultaneous essential-load case, then the largest permitted motor start.
5. Observe existing PV during the outage when sunlight permits. Record charging, curtailment/shutdown and restart rather than writing “solar works.”
6. Test high state of charge/light load, low reserve, loss of internet, a controlled equipment stop, Smart Circuit commands and manual fallbacks.
7. If generator hardware is contracted, test start, stable transfer/operation, charging behavior, shutdown and return to battery; otherwise mark generator “not included.”
8. Restore the grid and verify reconnection, solar production, metering, alerts, export control and monitoring history.
9. Save the final one-line, settings, serials, screenshots/readings, test results, owner training and escalation contacts.

The current FranklinWH commissioning guide treats grid, solar, export and port settings as configuration items. They are not casual homeowner toggles. The approved utility mode and exact one-line govern what should be commissioned.

Do site, temperature, clearance, and communications change feasibility?

Yes. The aPower 2 data sheet lists indoor/outdoor installation, wall or floor mounting, a 357-pound unit weight, Type 3R enclosure, and a published operating range of -4°F to 122°F, with a limited derated extension at stated output. Those are product boundaries—not site approval.

Return a scaled layout addressing working space, local fire/electrical/building rules, habitable-room restrictions, egress, ignition sources, snow/ice, flooding, drainage, wall structure, lifting route, vehicle impact, disconnect visibility, emergency labeling and future replacement access. Use the installation guide’s current clearances for the exact equipment and mounting method; do not copy a generic spacing diagram from another generation.

Commissioning and warranty can depend on accounts, registration and connectivity. Identify router distance, Wi-Fi/Ethernet route, cellular limitations, homeowner and installer permissions, alert recipients, data export and recovery after a router or ownership change. Closeout must give the owner—not only the installer—working monitoring access and a documented support route.

How should Connecticut, Massachusetts, and Rhode Island approvals be routed?

Existing PV permission is the starting record, not authorization to add battery power, revise export controls or alter the protected bus.

State	Current evidence route	Do not proceed without
Connecticut	Identify Eversource or United Illuminating; preserve RRES/legacy tariff documents; use current utility interconnection and Energy Storage Solutions processes	Written application level, exact equipment/configuration, export mode, tariff/program effect, reservation status and authorization
Massachusetts	Identify investor-owned or municipal utility; use the utility’s current interconnection tariff; check Mass Save ConnectedSolutions separately	Utility determination on modification, metering/export/charge behavior, Authorization to Connect and separate program acceptance
Rhode Island	Use Rhode Island Energy or applicable municipal utility; RI Energy says existing-PV storage requires an updated solar interconnection agreement	Updated agreement, approved implementer/equipment decision if pursuing a program, export setting and post-work authorization

Connecticut Energy Storage Solutions’ eligible-equipment list dated June 5, 2026 names aPower 2 and aPower S, while stating final equipment approval depends on DERMS integration. That listing is not household eligibility, incentive reservation, contractor eligibility or proof Teamsun can enroll the system.

Mass Save’s current battery page lists FranklinWH as a participating manufacturer and permits qualifying storage added to existing solar. Manufacturer-level participation does not approve every SKU, utility, account, installer or dispatch result. Obtain current written program terms and compare reserve/control obligations with the outage goal.

Rhode Island Energy’s battery program says storage cannot be easily added to every existing PV system and the solar interconnection agreement needs updating. It also conditions enrollment on customer, equipment, implementer and control requirements. Record incentive assumptions as unconfirmed until the responsible administrator accepts the exact project.

For a new homeowner battery expenditure in 2026, enter $0 for a new §25D amount. The IRS page reviewed July 4, 2026 says the credit is unavailable for property placed in service after December 31, 2025. A prior carryforward is taxpayer-specific; obtain tax advice rather than letting a salesperson apply a new 30% line.

Who owns warranty and service after the retrofit?

FranklinWH’s U.S. limited warranty, effective May 2026, should be attached to the proposal for the exact SKU. Its current aPower 2 framework uses a 15-year or 60-MWh boundary and a 70% energy-retention endpoint, subject to terms, registration, authorized channels, operation and exclusions. Those figures do not promise labor, travel, diagnosis time, replacement availability, loan relief or continued solar production.

Complete this handoff matrix:

Event	First contact	Diagnosis labor/travel	Manufacturer claim	Existing-PV warranty	Temporary operation	Target response evidence
Battery/aGate alert	___	___	___	n/a / ___	___	written process, not an invented SLA
Existing inverter stops	___	___	___	___	___	retained-provider consent
Islanded solar will not restart	___	___	___	___	___	controls/meters/settings owner
Roof/service work needed	___	___	___	___	___	remove/reinstall and permit scope
Internet/account transfer	___	___	___	n/a	___	owner/admin access procedure
Installer closes or declines service	___	___	___	___	___	manufacturer/escalation route

Notify the original PV owner, lender/lessor and warranty provider before alteration when contracts require it. Record who owns removed equipment, monitoring credentials and production responsibility. A FranklinWH warranty cannot silently replace the original inverter, roof or workmanship warranties.

The system-upgrades route and maintenance/repair route describe possible conversation paths. They do not verify FranklinWH-specific support. Ask the contracted legal entity to state licensing, manufacturer standing, permitting, commissioning access and post-install service in writing.

What belongs in a matched FranklinWH retrofit quote?

Every bidder should price the same frozen design case. Do not compare one whole-home aPower S redesign with one essential-load aPower 2 retrofit as if the battery line were the difference.

Quote field	Bid A	Bid B	Evidence gate
Existing PV retained/replaced	___	___	exact model and warranty notice
aPower exact SKU/quantity	___	___	current data sheet and availability
aGate generation/topology	___	___	revised one-line
Protected/excluded loads	___	___	load/start worksheet
Smart Circuits/generator	___	___	exact optional hardware or excluded
Electrical/service/site scope	___	___	panel, meter, trench, protection, mounting
Utility/program scope	___	___	filer, fees, assumptions, approval hold point
Commissioning tests	___	___	signed test and closeout schedule
Existing-PV and battery service	___	___	responsibility matrix
Gross cash price	___	___	all adders/allowances/exclusions separated
Finance	___	___	cash price, amount financed, APR, fees, total payments
Schedule/change orders	___	___	dependencies and unit/allowance rules

Do not subtract a tax credit or program payment from contract price. Keep hardware/electrical/site cost, financing, utility/program receipts and tax treatment separate. Ask how expired pricing, equipment substitution, failed utility review, concealed service conditions and required roof/electrical work become change orders.

Request a FranklinWH retrofit evidence review only after the data room is assembled. The useful output is a testable one-line and responsibility schedule, not a promise based on a brand logo.

When should an owner proceed, pause, or stop?

Signal	Meaning	Action
Proceed	Exact existing equipment, ownership, aPower SKU, aGate generation, protected loads, site, utility path, commissioning and service are documented; contingencies are priced	Compare matched cash scope and contract evidence
Pause	Design may work, but one-line, model labels, load starts, utility determination, warranty consent, program decision or site detail is pending	Keep the field blank and assign a verifier/deadline
Stop	Bid relies on universal compatibility, mixes aPower 2/S specs, promises outage solar without a test, assumes PTO covers storage, subtracts a new 2026 §25D credit, or cannot name service ownership	Do not sign or release final payment

The best answer may be to preserve the existing solar and add aPower 2, rearchitect around aPower S during planned PV work, select a different supported storage path, repair solar first, or defer. The stoplight is evidence-based; it is not a product ranking.

Frequently asked questions

Can aPower 2 work with existing microinverters?

It is an AC-coupled retrofit candidate, but “microinverters” is not an exact compatibility result. Provide the model, quantity, aggregate AC rating, firmware/control behavior, combiner, breaker and one-line. The designer must show how the aGate meters and controls that PV on-grid and islanded.

Does adding FranklinWH require replacing my solar inverter?

Not automatically. An aPower 2 path can preserve a supported, healthy AC solar inverter. Replacement or rearchitecture may make sense for a failed inverter, planned expansion, unsupported controls or a deliberately selected aPower S direct-PV design. Require both scope and warranty consequences in writing.

Is aPower S just a newer aPower 2?

No. Both current products list 15 kWh, but aPower S is hybrid-coupled with four direct-PV MPPTs; aPower 2 is AC-coupled. Quote the exact SKU and configuration rather than combining their specifications.

Will my solar recharge the battery during an outage?

Only if the exact solar source is within the supported island, the aGate and controls are configured correctly, and load, battery state, sunlight and inverter behavior permit operation. Require a witnessed curtailment/restart test; ordinary grid-tied solar alone is not backup.

Does “whole-home backup” mean every appliance can run together?

No. It can describe topology. Concurrent running power, motor starts, energy, temperature and reserve still control which loads work. Large 240-V loads may need Smart Circuit rules, separate controls or exclusion.

Can I add a generator later?

Possibly under a currently released FranklinWH generator configuration. Preserve space and one-line options, but do not assume any generator, vehicle outlet or transfer switch will integrate. Get exact hardware/model compatibility and permitting before calling the design generator-ready.

Does Connecticut program equipment listing guarantee an incentive?

No. The list is one equipment gate and states final approval depends on DERMS integration. Customer, contractor, utility, reservation, operating and project requirements remain separate.

Can I keep my existing solar warranty?

Maybe, but the contract controls. Ask the original owner, lessor/lender, installer and manufacturers whether changing breakers, metering, controls, strings or monitoring requires consent and which party owns a later fault.

Is there a 30% federal homeowner battery credit in 2026?

Not for new property placed in service after December 31, 2025 under the current IRS guidance. Use $0 in a 2026 residential proposal and send any carryforward or business-use question to a qualified tax adviser.

How many aPower 2 batteries do I need?

There is no defensible count from home size or bill amount. Use measured running/start loads, required hours, reserve, islanded solar behavior, site/service limits and the exact utility-approved configuration.

Can the battery join a demand-response program and still provide backup?

Potentially, but dispatch events, reserve controls, enrollment terms and equipment/implementer eligibility can affect available energy. Obtain the current written program case and test lower-reserve consequences rather than adding an incentive headline to every quote.

What should I receive before final payment?

At minimum: permits/inspection and utility authorization; as-built one-line/site plan; equipment/serial/firmware list; settings and meter map; commissioning/outage results; circuit schedule; monitoring ownership; warranty registrations; operating instructions; and service/escalation contacts.

Sources and research method

This article was researched August 10, 2026. Product facts came from the current FranklinWH aPower 2 and aPower S data sheets, aGate 1.3/1.3.1 installation guide, commissioning guide, backward-compatibility statement, Smart Circuits and generator pages, and May 2026 warranty. Program and tax routing came from Connecticut Energy Storage Solutions/PURA, Mass Save/Massachusetts utility guidance, Rhode Island Energy and the IRS. Current exact-intent search results and homeowner forum discussions were used only to identify questions about inverter preservation, aGate generations, generator claims, breaker scope and service continuity; no forum price, compatibility or performance claim was adopted.

The Teamsun live sitemap and repository were checked before drafting. The current FranklinWH-versus-Enphase page owns product comparison; the AC-versus-DC page owns general architecture; the Powerwall retrofit page owns Tesla; the planned Enphase retrofit page owns Enphase. This page alone owns the FranklinWH-specific existing-PV data room, aPower 2-versus-S gate, aGate/hardware one-line, failure testing, CT/MA/RI amendment route and service handoff.