A 3,500 square foot home in Delaware typically uses about 1,691 kWh per month at the state average rate of 14.8¢/kWh (EIA). With 4.5 peak sun hours per day, most homeowners need a 15.1 kW solar system — roughly 38 panels at 400W. After the 30% federal ITC, net cost is about $31,600, with 12.1-year payback and $77,900+ in estimated 25-year savings.
Content roles: This page is your Delaware-specific sizing decision for 3,500 sq ft. For national methodology and roof/orientation depth, see the 3,500 sq ft national guide. For bill-based sizing, see $300/month (~$250/mo equivalent in Delaware). Policy depth: Delaware solar data.
⚡ System Size
How Many Solar Panels for a 3,500 sq ft House in Delaware?
Delaware electricity rates and sun hours change panel count versus the US average:
System size (kW) = Annual kWh ÷ (Peak sun hours × 365 × 0.82)
For 3,500 sq ft in Delaware:
Estimated monthly usage: ~1,691 kWh
Peak sun hours: 4.5 h/day
System size:15.1 kW (~38 × 400W panels)
Metric
Delaware
US average
Rate
14.8¢/kWh
16.3¢/kWh
Sun hours
4.5 h/day
4.5 h/day
System size
15.1 kW
15.1 kW
Panels (400W)
38
38
Delaware requires a similar system than the national average for the same square footage. Use our solar system size calculator with your actual utility bills for a precise ZIP-level result.
Find your exact solar savings
Enter your ZIP code for a personalized estimate using your state's electricity rate and sun hours.
💰 System Cost
What Does Solar Cost for a 3,500 sq ft Home in Delaware After the ITC?
At $3.00/W installed (SEIA 2026), a 15.1 kW system in Delaware costs about $45,200 before incentives. The 30% ITC saves ~$13,560, for $31,600 net cost.
📈 Payback Period
How Long Is Solar Payback on a 3,500 sq ft Home in Delaware?
A 15.1 kW system saving ~$2,613/year pays back in about 12.1 years after the ITC. At 3% rate escalation, 25-year utility spend totals ~$109,500 vs $31,600 net solar — $77,900+ lifetime advantage.
Solar vs utility company · 25-year comparison
Total cost of staying on the grid vs owning solar for a $300/month bill (national average assumptions).
Delaware’s Green Energy Program provides grants for residential solar installations — typically $500–$1,000 depending on system size and funding availability. Delaware also has a Renewable Portfolio Standard and net metering policy that credits homeowners at the full retail electricity rate.
At Delaware's average rate of 14.8¢/kWh and 4.5 peak sun hours, a 3,500 sq ft home (~1,691 kWh/month) typically needs a 15.1 kW system — about 38 panels at 400W. See the [national 3,500 sq ft guide](/guides/how-many-solar-panels-3500-sq-ft-house/) for methodology.
A 15.1 kW system in Delaware costs roughly $45,200 installed before incentives. The 30% federal ITC reduces net cost to about $31,600. Delaware's Green Energy Program provides grants for residential solar installations — typically $500–$1,000 depending on system size and funding availability. Delaware also has a Renewable Portfolio Standard and net m...
At $31,600 net cost and ~$2,613/year in bill savings, simple payback in Delaware is about 12.1 years.
Most Delaware homeowners in this size range see **$77,900+** estimated 25-year savings vs utility power. Equivalent monthly bill: **~$250** — compare the [$300/month bill guide](/guides/solar-panels-300-month-electric-bill/) for bill-based sizing.
The US average needs a 15.1 kW system at 11.0-year payback. Delaware needs 15.1 kW with 12.1-year payback at 14.8¢/kWh and 4.5 sun hours.
$300/month electric bill by state
System size and payback vary by electricity rate and sun hours — see your state.