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Last Updated: January 17, 2026
Solar Generator Sizing: Interactive Calculator + Expert Guide
This solar generator sizing guide answers the question that determines whether your backup power actually works—or fails when you need it most. Use our calculator below to get your exact capacity in 60 seconds, then read the expert guidance to make the right purchase.
The $800 Mistake I Made
Bought a 1000Wh solar generator thinking it would run my refrigerator during outages. The math seemed right—fridge uses 100W, so 1000Wh should last 10 hours, right?
Wrong. Compressor surge draws 600W. Other loads running simultaneously. Efficiency losses. That "10 hours" became 6 hours. My food spoiled anyway.
Proper solar generator sizing would have saved $800 and a freezer full of meat. The calculator below does what I should have done.
Skip the math: Use the calculator below to get your exact numbers.
Camping: 500-2000Wh for devices, lights, small appliances.
Emergency Backup: 2000-4000Wh for refrigerator + essentials.
Whole House: 5000Wh+ for extended outage coverage.
Golden Rule: The calculator adds 30% safety margin automatically.
⚡ Solar Generator Sizing Calculator
Calculate exact battery capacity, solar panels, and inverter size for your off-grid needs
1
Select Your Appliances
Set quantity and hours per day for each appliance you want to power
2
Configure Your Settings
Adjust based on your location and backup requirements
Depth of Discharge (DoD) determines how much of your battery capacity is actually usable. Lithium batteries allow deeper discharge without damage.
How many consecutive days do you need backup power without any sun? More days = larger battery bank required.
Average hours of strong sunlight your location receives daily. This affects how many solar panels you need to recharge.
Extra capacity buffer for inverter efficiency losses, battery degradation, and unexpected power needs. 30% is recommended.
Ready to see your solar generator sizing results?
✅ Your Solar Generator Sizing Results
Based on your appliances, usage patterns, and settings
Battery Capacity Needed
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Wh
Daily Consumption
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Wh/day
Solar Panels Needed
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Watts
Minimum Inverter Size
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🎯 Recommended Systems For Your Needs
📊 Your Load Breakdown
| Appliance | Watts | Qty | Hours | Daily Wh |
|---|---|---|---|---|
| TOTAL DAILY CONSUMPTION | 0 Wh | |||
⚡ WATTSON'S TIP:
These numbers include your safety margin and account for surge loads. Don't buy smaller thinking you can "get by"—undersizing is the #1 solar generator mistake. If your result is 3500Wh, buy a 4000Wh system. You'll thank me when your power stays on.
Affiliate Disclosure: We earn commissions from qualifying purchases. This doesn't affect our recommendations—we only feature products we personally use and trust.
Wattson's Solar Generator Sizing Rule
The biggest mistake? Trusting marketing specs. That "1000Wh" generator delivers maybe 800Wh usable. That refrigerator "running 100W" surges to 600W on startup. The calculator above accounts for all of this. Trust the numbers it gives you, not the numbers on the box.
Solar Generator Sizing: Quick Reference Chart
Already know your use case? This chart provides quick solar generator sizing benchmarks. For precise numbers based on YOUR appliances, use the calculator above.
| Use Case | Capacity Needed | Panel Wattage | Example System |
|---|---|---|---|
| Phone/Laptop Only | 300-500Wh | 50-100W | Basic portable station |
| Weekend Camping | 500-1000Wh | 100W | Jackery 1000 |
| Extended Camping/RV | 1500-2500Wh | 200-400W | Goal Zero Yeti 1500X |
| Emergency Backup | 2000-4000Wh | 400-800W | Anker SOLIX F3800 |
| Whole House | 5000-10000Wh+ | 1000W+ | Expandable system |
| Off-Grid Cabin | 6000-10000Wh | 600-1200W | Custom battery bank |
These are starting points. The calculator provides exact numbers based on your specific appliances and settings.
The Rancher's Reality Check
When I sized systems for ranchers, they always forgot about the well pump. "Just the house," they'd say. Then the power goes out and they can't water livestock. Solar generator sizing isn't about what you normally use—it's about what you can't live without. The calculator includes well pumps for a reason.
Solar Generator Sizing: Critical Factors
The calculator handles the math, but understanding these factors helps you make smarter decisions:
Battery Chemistry Matters
LiFePO4 batteries allow 80-90% depth of discharge. Lead-acid only allows 50%. A 5000Wh lithium battery delivers 4000Wh usable. A 5000Wh lead-acid delivers only 2500Wh usable. The calculator lets you select battery type and adjusts accordingly.
Surge vs. Running Watts
Refrigerators, pumps, and AC units draw 2-3x their running watts on startup. Your inverter must handle the surge, or it shuts down. The calculator tracks surge requirements and sizes your inverter appropriately.
Peak Sun Hours Vary by Location
Arizona averages 6+ hours of peak sun. Seattle averages 3-4 hours. The calculator lets you select your region so panel sizing reflects reality, not best-case scenarios.
Days of Autonomy
How many days do you need power without sun? Emergency backup typically needs 2 days. Off-grid living might need 5-7. More autonomy = bigger battery. The calculator multiplies accordingly.
For detailed component guidance, see our Battery Bank Sizing Guide and Inverter Sizing Guide.
Solar Generator Sizing: Top Recommendations by Size
Based on your calculator results, here are our top picks:
Under 1500Wh: Camping & Light Use
Jackery Explorer 1000 or Goal Zero Yeti 1000 — Reliable, proven brands. Handles phones, lights, laptops, small devices. Perfect for weekend camping.
1500-3000Wh: Extended Camping & RV
Goal Zero Yeti 1500X or EcoFlow Delta 2 Max — Runs small refrigerators, CPAP machines, multiple devices simultaneously. Good for extended RV boondocking.
3000-6000Wh: Home Emergency Backup
Our Top Pick: Anker SOLIX F3800
3840Wh capacity. 3200W continuous output. 2400W solar input. Expandable to 26.9kWh with additional batteries. Powers whole-house essentials for 2+ days. Check current price on Amazon.
Read our full Anker SOLIX F3800 review.
6000Wh+: Off-Grid Living
Custom battery bank with Battle Born LiFePO4 batteries, quality inverter, and dedicated solar array. See our Component Selection Guide for building a complete system.
Wattson's Buying Advice
If your calculator result is 3500Wh, don't buy a 3500Wh system thinking you'll "get by." Buy the next size up. Batteries degrade over time. Your needs might grow. Weather might be worse than expected. The small extra cost now prevents the massive regret later.
Want Expert Help With Your System?
Get personalized recommendations based on your calculator results and specific situation.
GET FREE BUYER'S CHECKLISTWhat size solar generator do I need for my house?
For whole-house essential backup, you typically need 3000-6000Wh capacity. Use the calculator above to input your specific appliances—it accounts for surge loads and efficiency losses automatically. A 3840Wh system like the Anker SOLIX F3800 handles most home essentials for 1-2 days.
What size solar generator for camping?
Weekend camping requires 500-1000Wh for phones, lights, and small devices. Extended trips with cooler or CPAP need 1500-2000Wh. Use the calculator with your specific camping gear for exact sizing.
How big of a solar generator to run a refrigerator?
A standard refrigerator uses 1000-2000Wh per day (compressor cycles on and off). For 24-hour runtime, you need at least 2500Wh capacity plus 600W+ surge handling for compressor startup. The calculator accounts for surge automatically when you select "Refrigerator."
What size solar generator for an RV?
RV power needs vary from 1500Wh (basic: lights, devices, fan) to 5000Wh+ (full comfort: AC, microwave, entertainment). Most RVers find 2000-3000Wh adequate for extended boondocking without AC. Use the calculator with your specific RV appliances.
Why does the calculator add a safety margin?
Real-world efficiency is 80-85%, not 100%. Batteries degrade over time. Temperature affects performance. Unexpected loads happen. The 30% default margin (adjustable in settings) ensures your system actually delivers when you need it.
Should I buy exactly what the calculator recommends?
Buy the next size up if possible. If the calculator says 3500Wh, a 4000Wh system gives you room for growth, battery degradation, and worst-case scenarios. The small extra cost prevents major regret.
Solar Generator Sizing: The Bottom Line
Stop guessing. Use the calculator above to get your exact solar generator sizing based on YOUR appliances, YOUR location, and YOUR backup needs. It accounts for surge loads, efficiency losses, battery chemistry, and safety margins automatically.
Quick rules if you're in a hurry: Camping needs 500-2000Wh. Emergency backup needs 2000-6000Wh. Off-grid living needs 6000-10000Wh+. Always buy one size up from your calculated minimum.
The calculator took me 14 years of trial and error to get right. Use it. Trust the numbers. Size it right the first time.
Affiliate Disclosure: We earn commissions from qualifying Amazon purchases. This doesn't affect our recommendations—we only feature products we personally use and trust. See our full disclosure.