Tiny House Solar & Battery Planner
Start with the energy you actually use. This tool converts daily load into a rough battery and panel target while keeping the sun-hours and loss assumptions visible.
Based only on the simultaneous AC load and headroom you entered.
NREL's current PVWatts model uses weather/location data and explicitly models system losses; its online calculator currently shows an estimated default system-loss value around 14%. For a real design, check location-specific production, equipment limits, battery chemistry, surge loads, temperature, wiring, overcurrent protection and applicable electrical code.
This calculator does not design an electrical system and does not determine code compliance. “Peak sun hours” is a simplified planning input, not actual daylight duration. Solar production varies by location, season, tilt, orientation, shading, temperature and equipment.