Solar System & Battery Sizing for 775 kWh/Month in Illinois, USA
Complete photovoltaic engineering breakdown for a 775 kWh/month (25.8 kWh/day) electricity profile in Illinois, USA (4.4 Peak Sun Hours/day).
Technical Specification Table — 775 kWh/Month Solar System (Illinois, USA)
| Monthly / Daily Electricity Consumption | 775 kWh/month (25.8 kWh/day) |
| Location Peak Sun Hours (PSH) | 4.4 hours/day (Illinois, USA) |
| Required PV System Size (80% Performance Ratio) | 7.48 kWp DC |
| Number of Solar Panels (440W N-Type Bifacial) | 17 panels |
| Roof Area Required | 34.8 m² (375 sq ft) |
| Recommended Hybrid Inverter Rating | 6.7 kW AC |
| Recommended LiFePO4 Battery Storage (85% DoD) | 19.8 kWh Nominal (16.8 kWh Usable) |
| Estimated Annual Output | 9,610 kWh/year (~801 kWh/month) |
| Estimated System Turnkey Cost (Before Tax Credits) | $20,196 |
| Annual Electricity Bill Savings (@ $0.17/kWh) | $1,634/year ($136/month) |
Frequently Asked Questions
How many solar panels are needed for 775 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 775 kWh (25.8 kWh/day) requires a 7.48 kWp solar array, which equals 17 standard 440W N-Type solar panels occupying 34.8 m² (375 sq ft) of roof space.
What size solar battery bank do I need for 775 kWh/month?
To cover evening and overnight loads (65% of daily consumption at 85% LiFePO4 depth of discharge), a 19.8 kWh nominal (16.8 kWh usable) LiFePO4 battery bank paired with a 6.7 kW hybrid inverter is recommended.
How much money will a 7.48 kW solar system save in Illinois, USA?
Generating approximately 9,610 kWh per year at an average local tariff of $0.17/kWh, the system saves $1,634 per year ($136/month) with an estimated payback period of 12.4 years.