Bendt Residence Energy Resilience Master Plan

Executive brief

House

≈1,900 ft²

Florida home, built around 2004

Cooling equipment

3 tons

Bryant 215BNA036 heat pump

Current summer energy

60–80 kWh/day

At approximately 73°F day / 71°F night

Generator candidate

7 kW LP

GM9000iET propane running rating supplied by owner

1. Reliability first

Install a practical generator backup path before hurricane season.

2. Measure before buying

Use service, generator and HVAC submeters to replace assumptions with real load profiles.

3. Reduce the load

Compare Manual J/S, commissioning, duct work and envelope improvements against added battery and solar cost.

4. Buy the durable system

Size GridBOSS, FlexBOSS21 and battery cabinets after the house has been measured and improved.

Core decision rule: the house is part of the energy system. A kilowatt-hour eliminated through air sealing, duct repair, controls or correctly selected HVAC does not need to be generated, stored, converted or fueled during an outage.

Existing conditions and confirmed equipment

Main panel	Square D QO, 30-space cover. Exact load-center catalog number and series remain unconfirmed.
Outdoor unit	Bryant 215BNA036-A, 208/230 V, compressor RLA 16.7 A, LRA 79 A, MCA 22.1 A, maximum breaker 35 A.
Air handler	FX4DNF037, 208/230 V, ½ HP blower, 4.1 A FLA, no electric heat kit listed.
Existing transfer switch	Connecticut Electric EmerGen 6-5000; useful history, but not the preferred long-term architecture.
Usage observations	About 60–80 kWh/day occupied in hot weather; about 35–40 kWh/day while away at a 78°F setpoint.

Unknowns that matter

Exact QO panel catalog number, series and OEM interlock compatibility.
True 1-minute and 15-minute whole-house peak demand.
Overnight kWh from sunset to sunrise.
HVAC share of daily and nighttime energy.
Duct leakage, infiltration and room-by-room design cooling load.
Actual propane consumption per generated kWh.

No equipment purchase should erase an unknown. Phase 1 is intentionally instrumented so Phase 2 can be sized from measured data.

Conceptual site and floorplan overlay

The underlying floorplan is owner-supplied. Markers and routes are conceptual—not surveyed or permit-ready. The proposed generator route reflects the plan to place the generator at the rear and bring the feeder through the attic to the garage electrical zone.

Phase 1 Phase 2 Monitoring

Owner-supplied floor plan of the residence

Phase 1 — immediate hurricane backup and instrumentation

Backup power

GM9000iET generator candidate.
Outdoor 120/240 V inlet and long feeder to garage.
OEM-listed QO interlock after exact panel identification.
Manual outage load management.

HVAC readiness

Install a correctly selected soft-start.
Record pre/post starting current if available.
Verify blower, refrigerant charge, airflow and static pressure.
Do not assume reduced inrush changes MCA or branch-circuit requirements.

Measurement

Main service: both 120 V legs.
Generator feeder: both legs.
HVAC: condenser or coordinated HVAC total.
Home Assistant history plus outdoor temperature and thermostat state.

Phase 1 safety gate: the exact load-center model and approved interlock must be confirmed before purchase. Panel, inlet, feeder, neutral/bonding and backfeed-breaker work should be permitted and completed or reviewed by a qualified electrician.

Measurement program — the evidence for Phase 2

Dataset	Minimum collection	Useful resolution	Decision unlocked
Main service power and energy	30–60 hot-weather days; repeat after improvements	1-minute power, daily and nighttime kWh	Battery energy, inverter headroom, base-load audit
HVAC power and runtime	Same weather period	1-minute plus thermostat state; faster capture if available	HVAC share, soft-start performance, comfort strategy
Generator power, runtime and propane	Monthly exercise plus every outage	Power, kWh, run hours, fuel added	Charge-current limit, fuel storage and auto-start strategy
Indoor/outdoor conditions	Continuous	Outdoor temperature/humidity, indoor setpoint and temperature	Weather normalization and Manual J comparison
Post-improvement baseline	At least 2 comparable weeks	Same sensors and setpoints	Verified reduction—not contractor promises

Suggested Home Assistant entities

sensor.grid_power_total
sensor.grid_energy_daily
sensor.generator_power_total
sensor.generator_energy_session
sensor.hvac_power
sensor.hvac_energy_daily
sensor.night_energy
sensor.base_load_rolling_30m

Data-quality checks

CT direction and phase mapping validated against known loads.
Energy totals checked against FPL data over several days.
Generator meter verified under a controlled resistive load.
Time synchronization and local data retention confirmed.
Missing-data alerts added before long-term analysis.

Interactive decision lab

Enter measured values when they become available. Defaults are planning placeholders based on current observations. This model is for comparing scenarios, not final engineering.

Whole-house daily energy (kWh)

Nighttime energy (kWh)

HVAC share of energy (%)

Measured peak demand (kW)

Overnight/base load (kW)

Battery bridge days

Emergency reserve (%)

Usable fraction / DoD (%)

Nominal kWh per cabinet

Modeled HVAC reduction (%)

Installed battery cost assumption ($/kWh)

HVAC/envelope budget ($)

Planning peak-sun hours

PV system efficiency (%)

Generator continuous kW on propane

Generator charge/load limit (%)

Current scenario

Overnight nominal battery

Planning cabinets

Full-day no-solar battery

Generator recharge time for one night

Daily kWh after modeled HVAC reduction

Nominal battery avoided

Modeled battery spend avoided

Cabinets after improvement

Planning PV before improvement

Planning PV after improvement

HVAC budget beaten by battery savings?

HVAC and envelope investment versus energy-system size

Current measured

Modeled after work

The second bar uses the editable HVAC share and reduction assumptions from the decision lab. Replace them with measured post-project data.

Measure and commission

Submeter HVAC, verify airflow, static pressure, refrigerant charge, thermostat operation and soft-start performance.

Calculate, do not guess

Obtain room-by-room ACCA Manual J loads and use Manual S for replacement equipment selection. Manual J is a peak-load calculation—not an annual energy forecast.

Test the building

Blower-door and duct-leakage tests identify infiltration and attic-duct losses. Air seal before adding insulation.

Re-measure, then buy batteries

Use comparable weather and setpoints to quantify the actual reduction before final cabinet and PV selection.

Investment	What it can change	How to judge it	Effect on backup system
Manual J / Manual S consulting	Correct design load and replacement equipment size	Room-by-room report, inputs documented, equipment selected from actual performance data	May avoid oversizing and reduce startup/running demand
Blower-door and duct testing	Quantifies infiltration and duct loss	Before/after test results	Can reduce daily and nighttime kWh, shrinking batteries and PV
Attic air sealing and insulation	Reduces ceiling heat gain and uncontrolled air movement	Scope tied to test findings; re-measure energy	Reduces stored-energy requirement every outage day
Duct repair and airflow correction	Improves delivered cooling and equipment efficiency	Leakage, static pressure, airflow and room comfort	Reduces generator runtime and battery cycling
Additional battery cabinet	Adds stored energy only	Usable kWh and outage objective	Improves runtime but does not reduce daily load
Larger solar array	Adds daytime production	Roof, shading, MPPT and seasonal production model	Reduces daytime battery draw and generator recharge

Procurement gate: when a proposed building/HVAC project costs less than the battery, inverter and solar capacity it measurably avoids—and also improves comfort and operating cost—it should normally be evaluated first.

Phase 2 — EG4 whole-home backup and self-consumption

Preferred first configuration

Backup / no intentional export

Grid supports loads and charging; batteries and generator provide outage resilience. Solar can be added later with export disabled or limited if supported and approved.

Optional operating mode

Self-consumption / zero export

Solar and batteries reduce grid purchases without intentionally sending power to the utility. Utility and AHJ requirements still need confirmation.

Deferred decision

Grid export

Net metering or export can be evaluated later. Deferring it avoids letting utility-credit assumptions drive the initial resilience design.

Architecture simplification is not exemption: backup-only or zero-export operation may simplify goals and paperwork, but service-connected equipment still requires listed anti-islanding behavior, permits, inspections, grounding/bonding design and any required utility coordination.

Likely data-driven scenarios and decision points

Scenario A — modest overnight load

Likely 2 cabinets

Night energy is roughly 12–18 kWh, peak demand stays under about 9 kW, and HVAC starts cleanly.

Response:

One FlexBOSS21 and a moderate battery bank may be enough. Generator recharges after extended cloud or multi-night outages.

Scenario B — large overnight cooling demand

HVAC gate

Night energy is 25 kWh or more and HVAC exceeds half of total energy.

Response:

Commission Manual J/S, blower-door and duct testing before purchasing a third or fourth cabinet.

Scenario C — peak demand near 12 kW

Load control

Routine coincident loads approach the FlexBOSS21 battery-only output rating.

Response:

Automatically shed water heating, dryer, pool and EV loads; stage compressor and generator charging before considering a second inverter.

Scenario D — high base load

Audit

Overnight/base demand remains above about 1 kW even when HVAC is off.

Response:

Identify water heating, pool pumps, refrigeration and always-on equipment before adding storage.

Scenario E — generator runs too long

Fuel strategy

Measured battery recharge takes many hours or the generator stays near maximum continuous output.

Response:

Reduce AC charge current, shed house loads while charging, adjust battery reserve, or reconsider generator/battery balance.

Scenario F — improvements outperform estimates

Resize downward

Air sealing, ducts and HVAC work materially reduce hot-weather nighttime energy.

Response:

Re-run the sizing model and avoid buying cabinets or PV capacity no longer needed.

Implementation roadmap and gates

Identify and permit

Confirm panel catalog number/series, approved interlock, inlet location, feeder route, grounding/bonding approach and local permit scope.

Install Phase 1

Generator inlet/interlock, soft-start, monitoring hardware, Home Assistant entities and safe generator operating procedure.

Collect hot-weather baseline

30–60 days with stable sensors; include occupied, overnight, away and generator-test periods.

HVAC and envelope decision

When HVAC share or nighttime energy is high, purchase analysis and diagnostic work before storage hardware.

Re-measure and freeze Phase 2 requirements

Set inverter count, battery cabinet count, smart-load plan, generator charge limit and preliminary PV target.

Engineer and install EG4 system

Produce permit-ready one-line and site plan using current hardware-specific manuals, listings and service architecture.

Add solar after commissioning

Size strings from roof/shading and MPPT requirements; choose backup-only, zero-export or approved export mode.

Failure-mode principle: utility transfer, generator control, battery protection and load shedding must fail safely without Wi-Fi, cloud service or Home Assistant. Home Assistant is the supervisory and analysis layer, not the sole safety controller.

Sources, facts and assumptions

Official references

EG4 GridBOSS product page — 200 A service architecture and smart-load ports.
GridBOSS hardware-specific user manual.
EG4 FlexBOSS21 product page — 12 kW battery-only, up to 16 kW with PV contribution, 21 kW usable PV input.
FlexBOSS21 specification sheet.
Shelly 3EM-63 Gen3 documentation — three-channel metering, local protocols and data logging.
ACCA Manual J residential load calculation.
ACCA approved software directory.

Owner-supplied project facts

Floorplan, equipment nameplates, current usage observations, generator candidate/rating, desired rear generator location, garage equipment concept, and future outdoor battery preference were supplied in the project discussion.

Planning assumptions

Calculator defaults—including cabinet size, installed cost per kWh, peak-sun hours, reserve and expected HVAC reduction—are editable placeholders. They are not quotations, production guarantees or final equipment sizing.

Document status: concept design and decision framework. It is not a construction drawing, electrical one-line for permitting, structural plan, Manual J report, solar-production guarantee or equipment-submittal package.