Solar Design Tool

01

Project Information

Designer and PE attribution, AHJ selection, and project metadata. The PE name is required only when generating a final stampable output package (Phase 8).

Project number

Design date

Designer name

PE name required at output (Ph. 8)

Property address

Authority Having Jurisdiction

Selecting an AHJ pre-fills site wind speed and ASHRAE design temperatures. Site values may be overridden per the ASCE 7 Hazard Tool result for a specific address.

02

System Architecture

The composer in backend/calc/compose.py is built to support exactly these five topologies. Switching architecture clears any incompatible inverter or battery selection.

PV + String

Modules to a central string inverter. No battery.

PV + Microinverters

Per-module inversion. Branch trunk to AC. No battery.

PV + Hybrid + DC Battery

Sol-Ark / Energy Hub-style. Battery on the DC bus.

PV + Microinverters + AC Battery

Enphase IQ Battery / FranklinWH-style. AC-coupled storage.

PV + Powerwall

PW3 has integrated PV inverter. PW2 needs a separate string inverter.

03

Site & Roof

Wind and ASHRAE values are pre-filled from the AHJ; override per the ASCE 7 Hazard Tool result for a specific address.

Design wind speed ASCE 7-22 §26.5

mph

Exposure category ASCE 7-22 §26.7

Mean roof height ASCE 7-22 §26.3

ft

Roof type FBC R905

Roof pitch

deg

Roof azimuth (N=0°)

deg

ASHRAE extreme min temp NEC 690.7(A)

ASHRAE 2% high temp NEC 690.7

Latitude PVGIS / PVWatts

°N

Pre-filled from AHJ centroid; override per address.

Longitude

°E

West longitudes are negative.

04

Existing Service

Used by the 120 % rule and load-side / supply-side connection options in Phase 4.

Main panel busbar rating NEC 705.12(B)(3)

A

Main breaker rating NEC 408.30

A

Cannot exceed busbar rating.

Service voltage

Service phase configuration

05

Loads

Used to drive the NEC 220 service-load calculation that runs in Phase 4. Phase 2 captures inputs only.

Conditioned square footage NEC 220.41

ft²

HVAC tonnage

tons

EV charger present

Yes No

Pool pump present

Yes No

Other major loads

kW

Sum of any non-listed major loads (well pump, hot tub, on-demand water heater, workshop). Optional; defaults to 0.

06

Equipment Selection

Drop-downs are filtered by architecture and roof type. Components flagged verification_required show an amber warning — those values still need PE spot-check before stamping.

PV array configuration multi-orientation supported

For hip roofs or 4-side designs, add a sub-array per roof plane. Single-orientation designs use one sub-array.

Inverter

Inverter quantity

For string/hybrid: typically 1. For microinverters: locked to module quantity.

Battery

Racking system

Filtered by selected roof type. Attachment allowable uplift drives Phase 5 fastener check.

DC home-run length DC ≤ 2 %

ft

One-way array → inverter. Optional.

AC run length AC ≤ 3 %

ft

One-way inverter → service panel. Optional.

DC wire size NEC 310.16

Source-circuit conductor (USE-2 / PV-Wire @ 90 °C).

DC conduit NEC Annex C

Trade size + type for fill check.

AC wire size NEC 310.16

Inverter output / backfeed conductor (THWN-2 @ 75 °C typ).

AC conduit NEC Annex C

07

Structural geometry

Optional. Roof and array as rectangles for ASCE 7-22 §29.4.4 wind-load and FBC R324.6 setback checks. Polygon support arrives in Phase 12. Leave blank to skip the structural calc.

Roof length plan view

ft

Roof width

ft

Array length

ft

Array width

ft

Setback from ridge FBC R324.6.2

in

18" if array ≤ 33 % roof; 36" if > 33 %.

Setback from eave

in

Left rake setback FBC R324.6.1

in

≥ 36" required on at least one rake.

Right rake setback

in

Dead load

psf

Module + racking. Typical 3–4 psf.

Tributary area / fastener

ft²

Roof area served by one attachment.

Wind directionality K_d ASCE 7-22 Tbl 26.6-1

0.85 default for buildings.

Topographic K_zt ASCE 7-22 §26.8

1.0 for non-hilly residential.

Ground elevation K_e ASCE 7-22 §26.9

1.0 for near-sea-level FL elevations.

Allowable uplift override FL Product Approval

lb

Per-fastener allowable. Leave blank to use the smallest across the racking system's attachments.

08

Battery sizing

Visible for battery architectures only. Phase 7 simple sizing — daily essentials × backup duration → required usable kWh, plus continuous and peak power checks. Hourly dispatch (PV charging during outage, time-of-use savings) lands in Phase 11.

Daily essential load critical-loads panel

kWh / day

Typical Pensacola: 7–11 (fridge + lights + internet), 13–25 with mini-split.

Backup duration PE engineering judgment

hr

72 hr = 3 days (Pensacola gate target).

Continuous critical load battery AC continuous rating

kW

Sum of simultaneous running draw on the critical-loads panel.

Peak critical load battery AC peak rating

kW

Surge from largest motor start (AC compressor, well pump). Typically 3–5× running.

09

Energy balance

Daily PV production vs daily home load + battery recharge target. Answers "can my array power the home AND charge the battery?" The simple methods of Phases 6 and 7 don't check this directly. True hourly dispatch is Phase 11.

Daily home load utility bill / Green Button

kWh / day

Average daily consumption (separate from NEC 220 service-amp peak). Typical 2400 sqft Pensacola home: 25–40 kWh/day.

Battery recharge target design choice

days

How many days the array should take to fully recharge an empty battery on top of serving home load. Smaller = more PV needed. Leave blank for offset-only check.

DC string sizing

Energy production

Energy balance

Battery sizing

Structural & geometry

AC sizing & interconnection

POI alternatives

Project Information

System Architecture

Site & Roof

Existing Service

Loads

Equipment Selection

Structural geometry

Battery sizing

Energy balance