Read the estimate as an energy budget
Each selected appliance contributes watts × operating hours per day ÷ 1,000 to daily kWh. The presets are illustrative continuous or average loads, not measurements of your appliances. For a cycling refrigerator, use measured daily consumption when planning a real installation.
For example, 13.5 kWh at 90% usable capacity provides 12.15 kWh. With a 10 kWh/day load and no solar, that is 1.215 days (29.16 hours). With an assumed 5 kWh/day of solar, the daily deficit falls to 5 kWh and the arithmetic balance lasts 2.43 days. This model now retains partial days instead of rounding an exhausted battery up to a full day.
Solar production is entered kW × peak sun hours × 0.80. This daily-average approximation cannot determine whether a battery bridges the night, whether an inverter starts a pump, or whether solar can restart during an outage. The 90-day limit is a modeling horizon, not guaranteed endurance. Test zero sun as well as your expected sunlight.
Rooftop solar does not by itself establish outage operation. Confirm islanding capability, transfer equipment, power limits, state of charge, and critical circuits with your installer. EV storage is available only with a compatible V2H system and an appropriate driving reserve.
See the EIA guide to measuring electricity for the distinction between power and energy. This guide supports the load calculation, not specific product compatibility or runtime. Model and example checked September 21, 2026.