Solar System & Battery Sizing for 3,900 kWh/Month in Arizona, USA
Complete photovoltaic engineering breakdown for a 3,900 kWh/month (130.0 kWh/day) electricity profile in Arizona, USA (6.4 Peak Sun Hours/day).
Technical Specification Table — 3,900 kWh/Month Solar System (Arizona, USA)
| Monthly / Daily Electricity Consumption | 3,900 kWh/month (130.0 kWh/day) |
| Location Peak Sun Hours (PSH) | 6.4 hours/day (Arizona, USA) |
| Required PV System Size (80% Performance Ratio) | 25.52 kWp DC |
| Number of Solar Panels (440W N-Type Bifacial) | 58 panels |
| Roof Area Required | 118.9 m² (1,280 sq ft) |
| Recommended Hybrid Inverter Rating | 22.8 kW AC |
| Recommended LiFePO4 Battery Storage (85% DoD) | 99.4 kWh Nominal (84.5 kWh Usable) |
| Estimated Annual Output | 47,692 kWh/year (~3,974 kWh/month) |
| Estimated System Turnkey Cost (Before Tax Credits) | $62,524 |
| Annual Electricity Bill Savings (@ $0.15/kWh) | $7,154/year ($596/month) |
Frequently Asked Questions
How many solar panels are needed for 3,900 kWh per month in Arizona, USA?
With an average of 6.4 Peak Sun Hours per day in Arizona, USA and an 80% system performance ratio, a monthly usage of 3,900 kWh (130.0 kWh/day) requires a 25.52 kWp solar array, which equals 58 standard 440W N-Type solar panels occupying 118.9 m² (1280 sq ft) of roof space.
What size solar battery bank do I need for 3,900 kWh/month?
To cover evening and overnight loads (65% of daily consumption at 85% LiFePO4 depth of discharge), a 99.4 kWh nominal (84.5 kWh usable) LiFePO4 battery bank paired with a 22.8 kW hybrid inverter is recommended.
How much money will a 25.52 kW solar system save in Arizona, USA?
Generating approximately 47,692 kWh per year at an average local tariff of $0.15/kWh, the system saves $7,154 per year ($596/month) with an estimated payback period of 8.7 years.