Delaware pays about 16.4¢ per kilowatt-hour for residential electricity and receives about 4.5 kWh per square metre per day of sunlight — 17th and 28th respectively among the 50 states and DC tracked here. Those two numbers set the ceiling on what rooftop solar returns in Delaware, and they point in opposite directions.
Where Delaware sits against the rest of the country
Delaware is 1.6¢/kWh above the median residential rate across this dataset (14.8¢/kWh) and 0.1 kWh/m²/day below the median insolation (4.6 kWh/m²/day). Under this site's standard assumptions, that combination puts Delaware 20th of 51 for modeled payback speed, at 13.1 years against a dataset median of 13.5 years.
What actually drives payback in Delaware
Delaware is rate-led: upper half of the dataset for electricity price (17th), lower half for sunlight (28th). Swap Delaware's sunlight for the dataset median and payback moves to 12.8 years (0.2 years of swing). Swap its electricity rate instead and payback moves to 14.3 years (1.2 years of swing). The rate swap is the larger of the two, so what a kilowatt-hour costs is the input deciding the outcome in Delaware.
State incentives on record
Recorded for Delaware: Green Energy Program rebates from utilities (Delmarva, DEMEC, DEC); SREC market; net metering.
No federal credit is applied above (Section 25D expired 31 December 2025), and export terms often matter more than the headline rate (net metering guide).
The modeled system, in numbers
At Delaware's sunlight level a 7 kW array produces roughly 8,968 kWh a year, worth about $1,471 in first-year bill savings at 16.4¢/kWh against an assumed $22,400 installed cost. A ten-year payback at this sunlight level would require a residential rate of about 22.4¢/kWh, which is 6.0¢ above what Delaware households pay today.
States with comparable economics
Delaware's closest analogues by modeled payback are Alaska (13.3 years), Georgia (13.3 years), District of Columbia (12.8 years). They arrive there from different rate and sunlight combinations, so their incentive rows are the useful comparison.
- Alaska — modeled payback 13.3 years
- Georgia — modeled payback 13.3 years
- District of Columbia — modeled payback 12.8 years