Solar canopy ROI model for river walk

Captured from Claude · 108 messages · 26 images · 1 file · started May 17, 2026
Compressed with AI · 18,400 -> 6,200 tokens (-66%) · 96 messages condensed

01COMPLETED WORK

Sized the array: 40 x 400 W = 16 kW; assumed 1,250 kWh/kW/yr (temperate-coastal canopy).
Flat-tariff model finished: ~20,000 kWh/yr, ~$3,600/yr savings, simple payback ~11.4 yr, 15-yr net ~+$13k.
Escalated model finished (4%/yr price rise, 0.5%/yr degradation): break-even ~9.8 yr, 15-yr net ~+$28.4k.
Cross-checked annual yield against NREL PVWatts at the river-walk coordinates; within 6%.

02CURRENT STATE

Two Python models agreed on. install_cost = $41,000 (turnkey, after incentives), price = $0.18/kWh.
Headline agreed: present the escalated case ($28.4k / 9.8 yr); keep the flat case as the conservative floor.
Current escalated model, verbatim:

cum, rows = -install_cost, []
for yr in range(1, 16):
    yield_yr = annual * (1 - 0.005) ** (yr - 1)   # degradation
    tariff   = price  * (1 + 0.04) ** (yr - 1)    # escalation
    cum     += yield_yr * tariff
    rows.append((yr, round(cum)))

print(rows[-1])      # (15, 28362)

03IN PROGRESS

Drafting the one-page board summary: ROI table done, narrative paragraph half-written.

04NEXT STEPS

Add a sensitivity row for +/- 10% install cost.
DECIDE: include battery storage in the v2 model vs keep PV-only for the board.
Export the cumulative-savings chart at 2x for the slide deck.
Send the summary to the city engineer for the permitting note.

05CONSTRAINTS

User: conservative assumptions for any number shown to the board.
Planning dept: canopy mounting only, no ground array (decided).
User: hard budget cap of $45k turnkey.

06CRITICAL CONTEXT

Yield assumption is the biggest lever on the result; PVWatts run used the river-walk coordinates.
Incentives are already netted out of install_cost — do not double-count them.

07DISCARDED ATTEMPTS

Ground-mount layout: rejected, no land and it blocks the path.
30-year horizon: rejected, panels warrantied 25 yr and the user wanted a 15-yr view.

ATTACHMENTS

Images

Photo of the river-walk seating area beside the river — Photo of the river-walk seating area where the solar canopies would go.

Line chart of cumulative net savings: flat tariff breaks even at 11.4 years, 4%/yr escalated at 9.8 years — Cumulative net savings by year: the flat tariff breaks even at 11.4 years, the escalated case at 9.8.

Files

File · solar-roi-model.py

Two ROI models in one script: flat and 4%/yr escalated tariff, with 0.5%/yr panel degradation.

The handoff brief, in seven sections.

Solar canopy ROI model for river walk