Santa Isabel, PR, United States
What that is equal to
🏠 743
homes powered for a year
at the US average of 10,500 kWh per household
🌍 2,896 t
CO₂ avoided annually
displacing grid power at 0.371 kg CO₂e/kWh (EPA eGRID)
🚗 630
cars taken off the road
an average passenger vehicle emits 4.6 t CO₂e a year
⚡ 22.3 million
electric vehicle miles
at roughly 0.35 kWh per mile
The pay-off
It pays for itself here. A panel on this roof delivers electricity at 7.0¢ a kWh against a local price of 18.4¢ — 62% cheaper than local power. The install is repaid after 9.1 years, inside the panel's 25-year life.
7.0¢ vs 18.4¢
cost per kWh: this panel vs the grid
levelised over 25 years including 0.5%/yr degradation
$12.8 million
to fit every building here
14,239 panels at $900 installed each
9.1 years
to break even
saving $1.44 million a year area-wide at today's price
Assumes $900 to install one 325 W panel — hardware, mounting,
microinverter, electrical work, labour and permitting — repaid only by the electricity it
avoids buying. No subsidies, tax credits, net-metering premium, financing cost or future
price rises are counted, and the figure is undiscounted. Electricity price is the
no state figure published for this area, so the US average is used (EIA, May 2026). A single panel is unusually expensive per watt because it
carries a whole array's fixed costs, which is why these numbers look worse than rooftop
solar generally does.
How this is calculated
| Buildings with roofs | 14,239 |
| × Panel rating | 325 W |
| × Annual yield per panel here | 548.2 kWh |
| Annual generation | 7,805,387 kWh |
Assumptions and limitations
- Yield is specific to this location: 548.2 kWh per panel per
year, from NASA POWER climatology transposed onto a tilted roof plane.
The same panel makes roughly 596 kWh in Phoenix and 265 kWh in Anchorage.
- Assumes a south-facing roof at a typical residential pitch, with a
~22% total system loss for soiling, shading, wiring, inverter, and heat.
- Counts every above-ground structure with a footprint of at least 20 m²,
so garages and outbuildings are excluded but barns and sheds of real
size are not. Building data is machine-derived and imperfect.
- No account is taken of roof orientation, obstructions, structural
condition, or whether the owner wants a panel.
Places like Santa Isabel, PR