Off-Grid Load Calculator
Build an appliance list to calculate daily kWh usage, monthly consumption, and peak watts. Get solar, battery, and inverter sizing recommendations for your off-grid system.
Appliances
Daily Total
1.98 kWh/day
Energy Usage Breakdown
Average Load Profile
Energy Usage Comparison
- LED lighting uses 80% less energy than incandescent bulbs
- DC-powered appliances avoid inverter losses (10-15% savings)
- Propane for heating and cooking reduces electrical load significantly
- Energy Star appliances can reduce consumption by 10-50%
- Running high-wattage items during peak sun reduces battery cycling
About This Calculator
The Off-Grid Load Calculator helps you audit your energy consumption to properly size a solar power system, battery bank, or generator. Build a detailed list of your appliances with their wattage and daily usage hours to calculate total kilowatt-hours (kWh) needed per day. This is the essential first step in designing any off-grid, backup, or renewable energy system—knowing your loads determines everything from panel count to battery capacity. With 2026 appliance efficiency improvements and DC appliance availability, achieving a comfortable off-grid lifestyle on 3-8 kWh/day is more practical than ever.
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How to Use the Off-Grid Load Calculator
- 1Add appliances using the preset list or enter custom devices with their wattage.
- 2Set the hours per day each appliance runs (use decimals for minutes: 0.25 = 15 min).
- 3Adjust quantity for multiple identical devices (e.g., 5 LED bulbs).
- 4Review your total daily kWh and peak wattage requirements.
- 5Enable Advanced mode to get specific solar, battery, and inverter sizing recommendations.
- 6Use the results to size your off-grid system components appropriately.
How to Calculate Energy Usage
The basic formula for energy consumption is:
Energy (Wh) = Power (W) × Time (hours)
Example Calculations:
| Appliance | Watts | Hours/Day | Wh/Day |
|---|---|---|---|
| Refrigerator | 150 | 8* | 1,200 |
| LED Lights (5 bulbs) | 50 | 6 | 300 |
| Laptop | 50 | 4 | 200 |
| WiFi Router | 10 | 24 | 240 |
| Total | - | - | 1,940 Wh |
*Refrigerators run about 8 hours total per day (cycling on/off)
Converting to kWh: 1,940 Wh ÷ 1,000 = 1.94 kWh/day
Monthly Usage: 1.94 kWh × 30 = 58.2 kWh/month
Annual Usage: 1.94 kWh × 365 = 708 kWh/year
Important Measurement Notes:
- Nameplate wattage is maximum draw, not typical usage
- Cycling appliances (fridges, AC) run only 30-50% of the time
- Variable loads (computers, TVs) depend on activity
- Use a kill-a-watt meter for accurate measurements over 24-48 hours
Understanding Peak vs Average Load
You need to track two different metrics for proper system sizing:
Peak Load (Watts): The maximum power if all devices run simultaneously. This determines your inverter size.
Average Load (Watts): Total daily Wh divided by 24 hours. This represents your continuous draw.
Example Off-Grid Home:
| Appliance | Running W | Surge W | Hours/Day | Wh/Day |
|---|---|---|---|---|
| Refrigerator | 150 | 450 | 8 | 1,200 |
| Well Pump | 750 | 2,250 | 0.5 | 375 |
| Lights (LED) | 100 | 100 | 6 | 600 |
| Laptop + Router | 60 | 60 | 12 | 720 |
| Microwave | 1,000 | 1,500 | 0.25 | 250 |
| Peak | 2,060 | 4,360 | - | - |
| Daily Total | - | - | - | 3,145 |
System Sizing from This Example:
- Inverter: 3,000W minimum (handles 2,060W running + 4,360W surge)
- Solar panels: 1.5-2 kW (3,145Wh ÷ 4 sun-hours × 1.3 losses)
- Battery bank: 6-8 kWh usable (3,145Wh × 2 days ÷ 0.8 DOD)
- Average load: 3,145 ÷ 24 = 131W continuous
Realistic Peak Management: Peak loads rarely occur simultaneously. Staggering high-draw appliances allows smaller inverter sizing:
- Avoid running microwave while washing machine runs
- Start well pump before turning on other motors
- Use timer circuits to prevent overlap
2026 Appliance Wattage Reference
Use these typical wattages for planning (always check nameplate for actual values):
Ultra-Low Power (Under 25W):
| Appliance | Watts | Notes |
|---|---|---|
| Phone/tablet charger | 5-15 | 2-3 hours to charge |
| LED bulb (equiv. 60W) | 8-10 | 800-900 lumens |
| LED bulb (equiv. 100W) | 12-15 | 1,500+ lumens |
| WiFi router | 8-15 | 24/7 operation |
| Modem | 8-12 | 24/7 operation |
| Smoke detector | 0.5-1 | Battery backup |
Low Power (25-100W):
| Appliance | Watts | Notes |
|---|---|---|
| Laptop (working) | 30-65 | Gaming: 80-120W |
| Ceiling fan | 25-75 | Speed dependent |
| TV (32-43") | 35-80 | LED/OLED most efficient |
| TV (55-65") | 60-120 | Standby: 1-5W |
| Chest freezer | 50-100 | Runs 30-40% of time |
| Gaming console (idle) | 30-50 | Gaming: 100-200W |
Medium Power (100-500W):
| Appliance | Watts | Notes |
|---|---|---|
| Refrigerator (standard) | 100-200 | Cycles 30-40% |
| Refrigerator (Energy Star) | 60-120 | Best efficiency |
| DC refrigerator (12/24V) | 40-80 | No inverter loss |
| Desktop computer | 150-350 | Gaming: 400-800W |
| Washing machine | 350-500 | Mostly motor |
| Sewing machine | 75-150 | Variable speed |
| Vacuum (corded) | 300-700 | Brief use |
High Power (500-1,500W):
| Appliance | Watts | Notes |
|---|---|---|
| Well pump (1/2 HP) | 500-750 | 3x startup surge |
| Well pump (1 HP) | 800-1,200 | 3x startup surge |
| Microwave | 800-1,200 | Short duration use |
| Coffee maker | 800-1,200 | 5-10 min/day |
| Toaster | 800-1,500 | 2-5 min/day |
| Hair dryer | 1,000-1,800 | Brief use |
| Window AC (5,000 BTU) | 500-700 | Cycles 30-50% |
| Window AC (10,000 BTU) | 900-1,200 | Cycles 30-50% |
| Portable heater | 750-1,500 | Propane preferred |
Very High Power (1,500W+):
| Appliance | Watts | Notes |
|---|---|---|
| Window AC (15,000 BTU) | 1,400-1,800 | Consider mini-split |
| Central AC (2 ton) | 2,500-4,000 | Very high demand |
| Electric water heater | 3,000-4,500 | Use propane/solar |
| Electric range/oven | 2,000-5,000 | Use propane |
| Electric dryer | 2,000-5,000 | Use propane/line dry |
| Welder (small) | 2,500-5,000 | Generator backup |
Very high power appliances are typically avoided or replaced in off-grid systems
DC Appliances: The Efficiency Advantage
Running DC appliances directly from batteries eliminates inverter losses (5-15%) and increases system efficiency.
2026 DC Appliance Options:
DC Refrigeration:
| Product Type | Watts | Daily Use | Price Range |
|---|---|---|---|
| DC fridge (3.5 cu ft) | 30-50 | 400-700Wh | $400-700 |
| DC fridge (7 cu ft) | 50-80 | 700-1,200Wh | $800-1,200 |
| DC chest freezer | 40-70 | 600-1,000Wh | $600-1,000 |
DC Lighting:
| Type | Watts | Lumens | Price |
|---|---|---|---|
| 12V LED bulb | 3-5 | 300-500 | $5-15 |
| 12V LED strip (per foot) | 2-4 | 200-400 | $1-3 |
| 12V LED panel | 10-20 | 1,000-2,000 | $20-40 |
DC Water Pumps:
| Type | Watts | Flow Rate | Price |
|---|---|---|---|
| 12V pressure pump | 60-100 | 3-5 GPM | $80-150 |
| 12V submersible (shallow) | 30-60 | 1-3 GPM | $50-100 |
| 24V submersible (deep well) | 100-200 | 2-5 GPM | $200-500 |
DC Fans and Ventilation:
| Type | Watts | CFM | Price |
|---|---|---|---|
| 12V ceiling fan | 20-40 | 300-800 | $50-150 |
| 12V desk/clip fan | 5-15 | 100-300 | $15-40 |
| 12V vent fan | 10-25 | 200-500 | $30-80 |
Efficiency Comparison Example: A DC refrigerator using 50W × 8 hours = 400Wh/day directly from batteries vs an AC refrigerator using 100W × 8 hours = 800Wh, then losing 10% in the inverter = 889Wh required from batteries.
The DC refrigerator requires 55% less solar capacity and battery storage for the same result.
Load Categories and Priorities
Organize your loads by importance for system sizing and load shedding:
Critical Loads (Must Always Run):
| Load | Typical Wh/Day | Notes |
|---|---|---|
| Refrigerator | 800-1,500 | Food safety |
| Chest freezer | 600-1,000 | Food preservation |
| Well pump | 200-500 | Water supply |
| Medical equipment | Varies | Life safety |
| Communication | 100-300 | Phone, internet |
| Security lighting | 50-150 | Safety |
| Critical Total | 1,750-3,950 | Size battery for 3+ days |
Essential Loads (Daily Comfort):
| Load | Typical Wh/Day | Notes |
|---|---|---|
| General lighting | 200-400 | LED throughout |
| Laptop/electronics | 200-500 | Work/entertainment |
| Kitchen appliances | 300-600 | Microwave, coffee |
| Ceiling fans | 200-400 | Comfort cooling |
| Essential Total | 900-1,900 | Size for 2 days |
Discretionary Loads (Nice to Have):
| Load | Typical Wh/Day | Notes |
|---|---|---|
| Television | 200-600 | Limit screen time |
| Gaming console | 300-800 | High draw when active |
| Washing machine | 200-400 | 2-3 loads/week |
| Shop tools | Varies | Run during peak sun |
| Extra lighting | 100-200 | Outdoor/decorative |
| Discretionary Total | 800-2,000 | Shed first in cloudy weather |
Priority-Based System Sizing:
- Minimum system: Critical loads only = 2-4 kWh/day = 1-1.5kW solar
- Comfortable system: Critical + Essential = 3-6 kWh/day = 1.5-2.5kW solar
- Full system: All loads = 4-8 kWh/day = 2-4kW solar
Seasonal Load Variations
Off-grid loads change dramatically by season. Plan for your peak usage periods:
Summer Peaks (Northern Hemisphere):
| Category | Summer Load | Winter Load | Difference |
|---|---|---|---|
| Air conditioning | 3,000-8,000Wh | 0 | +3,000-8,000 |
| Refrigerator | 1,500Wh | 1,000Wh | +500 |
| Fans | 500-1,000Wh | 0 | +500-1,000 |
| Lighting | 300Wh | 600Wh | -300 |
| Water pump | 500Wh | 300Wh | +200 |
Winter Peaks:
| Category | Winter Load | Summer Load | Difference |
|---|---|---|---|
| Heating (electric) | 5,000-15,000Wh | 0 | +5,000-15,000 |
| Lighting | 600Wh | 300Wh | +300 |
| Heated blanket | 200-400Wh | 0 | +200-400 |
| Humidifier | 100-300Wh | 0 | +100-300 |
Solar Production vs Load Mismatch:
| Month | Sun Hours | Solar kWh | Load kWh | Balance |
|---|---|---|---|---|
| January | 3.5 | 7.0 | 8.0 | -1.0 |
| April | 5.0 | 10.0 | 5.0 | +5.0 |
| July | 6.0 | 12.0 | 7.0 | +5.0 |
| October | 4.0 | 8.0 | 5.5 | +2.5 |
Strategies for Seasonal Balance:
- Size for worst month: Design for winter sun hours + winter loads
- Generator backup: 10-20 hours of generator time in winter
- Propane heating: Eliminates largest winter electric load
- Mini-split cooling: 50% more efficient than window AC
- Seasonal activities: Run high-draw tasks in summer when surplus
Reducing Your Load
The cheapest solar system is the one you never have to build. Reducing loads first makes your system smaller, cheaper, and more reliable.
High-Impact Changes (Save 3,000-10,000 Wh/day):
| Change | Electric Load | Alternative | Savings |
|---|---|---|---|
| Propane cooking | 1,000-2,000Wh | $20-40/mo propane | 1,000-2,000Wh |
| Propane water heater | 4,000-6,000Wh | $30-50/mo propane | 4,000-6,000Wh |
| Propane/wood heat | 5,000-15,000Wh | $100-200/mo fuel | 5,000-15,000Wh |
| Propane dryer | 2,000-4,000Wh | Line dry + gas | 2,000-4,000Wh |
| Mini-split vs window AC | 6,000Wh | 3,000Wh | 3,000Wh |
Medium Impact Changes (Save 500-2,000 Wh/day):
| Change | Before | After | Savings |
|---|---|---|---|
| LED vs incandescent | 600Wh | 75Wh | 525Wh |
| DC fridge vs AC | 1,200Wh | 600Wh | 600Wh |
| Laptop vs desktop | 800Wh | 200Wh | 600Wh |
| Chest vs upright freezer | 1,200Wh | 600Wh | 600Wh |
| Kill phantom loads | 1,500Wh | 200Wh | 1,300Wh |
Off-Grid Load Comparison:
| System Type | Daily kWh | Solar Needed | Battery Needed |
|---|---|---|---|
| Grid-connected home (US avg) | 30 | 10-12 kW | 60+ kWh |
| Standard off-grid | 8-12 | 3-5 kW | 20-30 kWh |
| Efficient off-grid | 4-6 | 1.5-2.5 kW | 10-15 kWh |
| Ultra-efficient | 2-3 | 0.8-1.2 kW | 5-8 kWh |
The Efficient Off-Grid Target: A well-designed off-grid home achieving full comfort typically uses 4-8 kWh/day. This requires:
- Propane for heating, cooking, water heating
- DC or Energy Star refrigeration
- LED lighting throughout
- No phantom loads
- Laptop instead of desktop
- Strategic AC usage (mini-split, peak sun hours)
Measuring Actual Usage
Nameplate wattage is often wrong. Measure actual usage for accurate system sizing:
Kill-A-Watt Meter ($20-30): The most important tool for load auditing. Plug it between an appliance and outlet to measure:
- Actual watts while running
- kWh consumed over time (leave plugged in 24-48 hours)
- Duty cycle (refrigerators, AC)
Measurement Protocol:
| Appliance Type | Measurement Period | What to Record |
|---|---|---|
| Refrigerator | 24-48 hours | Total kWh |
| Freezer | 24-48 hours | Total kWh |
| Air conditioner | 24 hours (hot day) | Total kWh |
| Washing machine | Per load | Wh per cycle |
| Computer | 8 hours work | Average watts |
| TV | Typical viewing | Average watts |
| Coffee maker | Per use | Wh per cycle |
Common Measurement Surprises:
| Appliance | Nameplate | Actual | Difference |
|---|---|---|---|
| Refrigerator (standard) | 150W | 40-60W avg | 60-75% less |
| LED TV 55" | 120W | 50-70W | 40-50% less |
| Laptop (web browsing) | 65W | 25-35W | 45-60% less |
| Gaming console (idle) | 200W | 30-50W | 75-85% less |
| Phone charger (charging) | 20W | 10-15W | 25-50% less |
| Phone charger (idle) | 20W | 0.5-2W | 90-97% less |
Whole-House Monitoring: For existing homes, consider a whole-house energy monitor ($100-300) that clamps onto your electrical panel. This shows:
- Real-time consumption
- Usage patterns by time
- High-draw event identification
- Monthly/yearly totals
Sample Off-Grid Load Profiles
Real-world examples to help estimate your needs:
Minimal Cabin (Weekends/Vacation):
| Load | Watts | Hours | Wh/Day |
|---|---|---|---|
| LED lights (4) | 32 | 4 | 128 |
| Phone charging | 10 | 2 | 20 |
| Small 12V fridge | 40 | 8 | 320 |
| Laptop | 40 | 3 | 120 |
| WiFi hotspot | 5 | 8 | 40 |
| Total | - | - | 628 Wh |
| System: 400W solar, 2kWh battery, 1,000W inverter |
Full-Time Off-Grid Home (Efficient):
| Load | Watts | Hours | Wh/Day |
|---|---|---|---|
| DC refrigerator | 50 | 8 | 400 |
| Chest freezer | 60 | 6 | 360 |
| LED lights (10) | 80 | 5 | 400 |
| Well pump | 700 | 0.5 | 350 |
| Laptop + router | 55 | 12 | 660 |
| TV | 60 | 3 | 180 |
| Kitchen misc | 300 | 0.5 | 150 |
| Washing machine | 450 | 0.3 | 135 |
| Ceiling fans (2) | 80 | 6 | 480 |
| Total | - | - | 3,115 Wh |
| System: 1.5kW solar, 8kWh battery, 3,000W inverter |
Off-Grid Home with AC (Summer Peak):
| Load | Watts | Hours | Wh/Day |
|---|---|---|---|
| Efficient fridge | 80 | 8 | 640 |
| Chest freezer | 60 | 6 | 360 |
| LED lights | 80 | 5 | 400 |
| Well pump | 700 | 0.5 | 350 |
| Electronics | 100 | 10 | 1,000 |
| Mini-split AC | 800 | 6 | 4,800 |
| Kitchen/misc | 500 | 0.5 | 250 |
| Total | - | - | 7,800 Wh |
| System: 4kW solar, 20kWh battery, 5,000W inverter |
Off-Grid Homestead with Workshop:
| Load | Watts | Hours | Wh/Day |
|---|---|---|---|
| House loads (efficient) | - | - | 3,500 |
| Workshop lighting | 200 | 2 | 400 |
| Air compressor | 1,200 | 0.5 | 600 |
| Power tools (avg) | 800 | 2 | 1,600 |
| Welding (small) | 2,500 | 0.5 | 1,250 |
| Total | - | - | 7,350 Wh |
| System: 4kW solar, 15kWh battery, 6,000W inverter (generator backup for heavy welding) |
From Load Audit to System Sizing
Once you know your daily kWh, calculate your system requirements:
Step 1: Adjust for Efficiency Losses Total system losses include:
| Loss Source | Typical Loss | Multiply By |
|---|---|---|
| Inverter efficiency | 5-10% | 1.05-1.10 |
| Wire losses | 2-5% | 1.02-1.05 |
| Battery efficiency | 5-15% | 1.05-1.15 |
| Controller losses | 2-5% | 1.02-1.05 |
| Total system | 15-30% | 1.20-1.35 |
Step 2: Calculate Solar Array Size Solar needed = (Daily kWh × Loss factor) ÷ Sun hours
Example: 5 kWh/day × 1.25 ÷ 4.5 sun hours = 1.39 kW minimum
Step 3: Calculate Battery Capacity Battery needed = Daily kWh × Days of autonomy ÷ Depth of discharge
Example: 5 kWh × 2 days ÷ 0.80 DOD = 12.5 kWh battery bank
Step 4: Calculate Inverter Size Inverter = Peak load × 1.25 safety margin
Example: 2,500W peak × 1.25 = 3,125W → Choose 3,500W inverter
Quick Reference Table:
| Daily kWh | Solar (kW) | Battery (kWh) | Inverter |
|---|---|---|---|
| 2 | 0.8-1.0 | 5-6 | 1,500W |
| 4 | 1.5-2.0 | 10-12 | 2,500W |
| 6 | 2.0-2.5 | 15-18 | 3,500W |
| 8 | 2.5-3.5 | 20-24 | 4,500W |
| 10 | 3.5-4.5 | 25-30 | 5,500W |
| 15 | 5.0-6.5 | 35-45 | 8,000W |
Based on 4.5 average sun hours and 2 days autonomy with LiFePO4 (80% DOD)
Pro Tips
- 💡Use a kill-a-watt meter ($20-30) to measure actual consumption—nameplate ratings often overstate usage by 30-70%, leading to oversized systems.
- 💡Phantom loads from devices on standby can total 50-100W continuously (1.2-2.4 kWh/day). Use smart power strips to eliminate them completely.
- 💡DC refrigerators running directly from batteries avoid 10-15% inverter losses—over time, this saves hundreds of dollars in solar panel and battery costs.
- 💡Run high-wattage appliances (washing machine, power tools) during peak sun hours when solar is producing maximum power, reducing battery cycling.
- 💡Switch to propane for heating, cooking, and water heating to eliminate 50-80% of typical household electrical load—the cheapest "solar savings" available.
- 💡A chest freezer uses 40-50% less energy than an upright freezer because cold air stays inside when opened.
- 💡LED lighting uses 80-90% less electricity than incandescent and 50% less than CFL. A full home LED conversion often costs under $50 and saves 300-500 Wh/day.
- 💡Calculate refrigerator runtime at 8 hours/day (33%) rather than 24 hours—they cycle on and off. Measure yours with a kill-a-watt for precise data.
- 💡Laptops use 30-65W vs 150-350W for desktop computers. For off-grid offices, laptops can reduce computing load by 70-80%.
- 💡Consider a 12V or 24V house DC circuit for lighting and fans. Running these loads directly from batteries eliminates inverter standby power (10-50W) when only small loads are active.
- 💡Mini-split air conditioners use 30-50% less energy than window units and can both heat and cool. The extra cost pays back quickly off-grid.
- 💡Prioritize loads into critical/essential/discretionary categories. Size your system for critical loads to always work, with discretionary loads available when solar is abundant.
Frequently Asked Questions
It depends on your lifestyle and willingness to adapt. A minimal cabin might need 2-3 kWh/day, an efficient full-time off-grid home 5-8 kWh/day, and a full-featured home with AC 10-15 kWh/day. The average US grid-connected home uses about 30 kWh/day, but efficiency measures can cut this by 50-80%. Start by auditing your current usage and identifying what can be eliminated, reduced, or switched to propane.
