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Calculate required solar panel wattage, MPPT controller amperage, and battery storage capacity with cloudy-day autonomy buffers.
Precision load audits, battery chemistry models, and solar insolation calculations
Input customized appliances, runtime hours, and motor surge requirements to calculate exact daily watt-hour consumption.
Computes required kilowatt-hours (kWh) and amp-hours (Ah) factoring in 90% Depth of Discharge (DoD) and cloudy-day autonomy buffers.
Sizes solar panel wattage based on local Peak Sun Hours (PSH) and calculates NEC-compliant MPPT charge controller amperage.
Solar arrays must be oversized by 20% to account for panel temperature heating, dust accumulation, and wiring voltage drops.
LiFePO4 lithium cells offer 90% usable depth of discharge, whereas lead-acid AGM banks require 2x capacity to stay above 50% DoD.
Compressors and pumps draw heavy inductive starting current, requiring pure sine wave inverters with at least 2x peak surge capacity.
Everything you need to know about Off-Grid Solar & Battery Storage
Divide your total daily watt-hour consumption (adjusted for inverter efficiency) by your location's Peak Sun Hours (PSH) multiplied by a 0.80 system loss derating factor: Array Watts = Daily Wh / (PSH x 0.80). Then divide by individual panel wattage.
Peak Sun Hours represent the equivalent number of hours per day when solar irradiance averages 1,000 Watts per square meter. In most regions, this ranges from 3.0 PSH (winter/northern climates) to 5.5+ PSH (sunny southern climates).
LiFePO4 lithium batteries can be discharged up to 90% without degradation and last 3,000 to 5,000 cycles. Traditional Lead-Acid batteries can only be discharged 50% and last 500 to 1,000 cycles, requiring twice the physical battery capacity.
Explore grid-tied solar savings, energy bill estimators, and carbon footprint calculators.
Visualizes real-time hourly power balance, solar generation bell curves, and battery State of Charge (SoC %) across a full day.
Days of Autonomy is the number of consecutive overcast, rainy, or snowy days your battery bank can power your home without any solar generation, typically sized for 2 to 3 days of backup reserve.
Use 12V for small RVs and camper vans (< 1,000W loads). Use 24V for medium cabins and tiny homes (1,000W to 3,000W). Use 48V for full residential off-grid homes (> 3,000W) to keep wire sizes and amperage manageable.
Inductive motor loads (refrigerators, AC compressors, well pumps) draw 2x to 3x their rated running wattage for a few seconds upon startup. Your pure sine wave inverter must have sufficient surge wattage to handle these starting loads.
Maximum Power Point Tracking (MPPT) controllers convert high-voltage solar panel output down to your battery voltage with 95%+ efficiency, harvesting up to 30% more energy than older PWM controllers.
Yes! Click 'Export CSV' to download complete appliance lists, daily watt-hours, panel counts, and battery capacities, or click 'Snapshot' for chart graphics.
Yes! You can add unlimited appliances, customize running watts, daily hours of operation, and mark inductive motor surge devices.
The model assumes modern pure sine wave inverters operating at 92% to 94% conversion efficiency.
Solar panels lose approximately 0.4% efficiency per degree Celsius above 25°C. This is factored into the 0.80 overall system derating factor along with wiring and dust losses.
No software installation is required. The Off-Grid Solar Sizing Lab runs client-side in your web browser using HTML5 Canvas and TypeScript.