Solar System & Battery Sizing for 1,425 kWh/Month in Illinois, USA
Complete photovoltaic engineering breakdown for a 1,425 kWh/month (47.5 kWh/day) electricity profile in Illinois, USA (4.4 Peak Sun Hours/day).
Technical Specification Table — 1,425 kWh/Month Solar System (Illinois, USA)
| Monthly / Daily Electricity Consumption | 1,425 kWh/month (47.5 kWh/day) |
| Location Peak Sun Hours (PSH) | 4.4 hours/day (Illinois, USA) |
| Required PV System Size (80% Performance Ratio) | 13.64 kWp DC |
| Number of Solar Panels (440W N-Type Bifacial) | 31 panels |
| Roof Area Required | 63.5 m² (684 sq ft) |
| Recommended Hybrid Inverter Rating | 12.2 kW AC |
| Recommended LiFePO4 Battery Storage (85% DoD) | 36.4 kWh Nominal (30.9 kWh Usable) |
| Estimated Annual Output | 17,525 kWh/year (~1,460 kWh/month) |
| Estimated System Turnkey Cost (Before Tax Credits) | $36,828 |
| Annual Electricity Bill Savings (@ $0.17/kWh) | $2,979/year ($248/month) |
Frequently Asked Questions
How many solar panels are needed for 1,425 kWh per month in Illinois, USA?
With an average of 4.4 Peak Sun Hours per day in Illinois, USA and an 80% system performance ratio, a monthly usage of 1,425 kWh (47.5 kWh/day) requires a 13.64 kWp solar array, which equals 31 standard 440W N-Type solar panels occupying 63.5 m² (684 sq ft) of roof space.
What size solar battery bank do I need for 1,425 kWh/month?
To cover evening and overnight loads (65% of daily consumption at 85% LiFePO4 depth of discharge), a 36.4 kWh nominal (30.9 kWh usable) LiFePO4 battery bank paired with a 12.2 kW hybrid inverter is recommended.
How much money will a 13.64 kW solar system save in Illinois, USA?
Generating approximately 17,525 kWh per year at an average local tariff of $0.17/kWh, the system saves $2,979 per year ($248/month) with an estimated payback period of 12.4 years.