The average US home uses 10,500 kWh/year and needs an 8–10 kW solar system. Your actual size depends on your consumption, location, and panel efficiency.
Your Energy Consumption
$
Your average monthly utility bill.
¢/kWh
US avg: 17.78¢/kWh
kWh/mo
Auto-calculated from Bill ÷ Rate. You can override.
kWh/yr
From your utility bills. US avg: ~10,500 kWh/yr.
¢/kWh
For savings calc. US avg: 17.78¢.
Location & Solar Resource
Selecting a state auto-fills peak sun hours and electricity rate.
hr/day
US avg: 4.5. SW USA: 6.0–6.5.
%
Accounts for inverter, wiring, temp losses. Default: 78%.
Panel & System Specs
Modern residential panels: 400–450W typical.
$/W
US avg 2025: $2.50–$3.50/W installed.
100%
50% (partial)100% (full offset)120% (export)
100% = fully offset your usage. 110–120% = generate excess for EV / battery / net metering.
Recommended System Size
7.8 kW
DC System Size
20 panels × 400W
Annual Savings
$1,800
per year
Est. System Cost
$23,400
installed
Annual Generation
11,250
kWh/year
Roof Space
350
sq ft needed
Payback Period13.0 years
25-Year Savings$45,000
CO₂ Offset4.3 tons/yr
Equivalent Trees Planted198 trees/yr
System Summary
Annual Consumption11,250 kWh/yr
System Size (DC)7.8 kW
Number of Panels20 panels
Peak Sun Hours4.5 hr/day
System Efficiency78%
Solar Offset Goal100%
Annual Generation11,250 kWh/yr
Monthly Solar Generation vs. Consumption
Estimated monthly profile based on your system size and location
Methodology: System Size (kW) = Annual Consumption (kWh) × Offset% ÷ (Peak Sun Hours/day × 365 × System Efficiency). System efficiency of 78% accounts for inverter losses (~4%), wiring losses (~2%), temperature derating (~3%), soiling (~2%), and mismatch losses (~1%). Panel count = ⌈System kW × 1000 ÷ Panel Wattage⌉. Annual generation = System kW × PSH × 365 × efficiency. Roof space = Panels × 17.5 sq ft (standard 60-cell panel). CO₂ offset uses US grid average of 0.386 kg CO₂/kWh. 25-year savings assumes 3% annual utility rate escalation and 0.5%/year panel degradation. Cost estimate is installed cost including equipment, labor, and permitting. This is a planning estimate only — contact a licensed solar installer for a site-specific proposal.
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