What Size Solar Generator Do I Need? (The Ultimate 2026 Calculator)
โก Key Takeaways
- Don't buy based on marketing hype. Most brands exaggerate their capacity.
- The Magic Formula: (Device Watts ร Hours) รท 0.85 = Battery Size needed.
- Inverter size matters: A 500Wh battery is useless if the inverter can't start your microwave.
Portable power stations are expensive. Buying one that is too small leaves you in the dark, while buying one that is too big is a waste of money. As an electrical engineer, I see people making the same mistake over and over: they confuse Watts with Watt-Hours.
In this guide, I will break down the physics, give you a simple calculator, and recommend the exact models for your needs.
1. The Physics: Watts vs. Watt-Hours
Before you spend $1,000, you need to understand the difference between these two numbers found on every box.
Watts (W) = Horsepower
This is the speed of power. It determines what devices you can run simultaneously.
- Phone Charger: 18W (Low)
- Laptop: 60W (Medium)
- Coffee Maker: 1000W (High)
If your generator has a 500W inverter, you simply cannot run a coffee maker. It will shut down immediately.
Watt-Hours (Wh) = Gas Tank Size
This is the volume of power. It determines how long you can run a device.
- Jackery 240: Has 240Wh of fuel.
- EcoFlow Delta Pro: Has 3600Wh of fuel.
2. The Calculation Formula
Batteries are not 100% efficient. When you convert DC power (battery) to AC power (wall outlet), you lose about 15% of energy to heat and fan noise. This is called "Inverter Efficiency."
Here is the formula I use for all my client setups:
Example: The "Digital Nomad" Setup
Let's say you want to work remotely from a campsite for 8 hours.
- MacBook Pro: 60W (uses average 30W)
- Starlink Internet: 50W
- Phone Charging: 10W
Total Load: 90 Watts.
Calculation: (90W ร 8 hours) รท 0.85 = 847Wh.
Verdict: A small unit like the Jackery 500 (518Wh) won't cut it. You need something in the 1000Wh class, like the EcoFlow Delta 2 or Jackery 1000.
3. Common Appliance Power Chart
Use this cheat sheet to estimate your needs.
| Device | Running Watts | Starting Watts |
|---|---|---|
| LED Light Bulb | 10W | 10W |
| CPAP Machine | 40W - 60W | 40W |
| Mini Fridge (12V) | 45W | 60W |
| Portable AC | 1000W | 1200W |
4. My Top Recommendations for 2026
Best for Weekend Camping: EcoFlow River 2 Pro
For light trips where you just need to charge phones, drones, and maybe a laptop, the River series is unbeatable due to its charging speed. It charges from 0-100% in just 70 minutes.
Best for Home Backup: Bluetti AC200MAX
If you need to keep the fridge running during a blackout, you need heavy capacity. The AC200MAX is expandable and uses LiFePO4 batteries, which last 10+ years.
Best Overall: Jackery Explorer 1000 v2
The "Goldilocks" size. Not too heavy to carry, but powerful enough to run a coffee maker or a small heater for short periods.
Conclusion
Don't buy a battery just because it looks cool. Do the math first. If you buy too small, you'll end up spending double when you have to upgrade a month later.
Need specific advice? Use the Contact form to send me your appliance list, and I'll help you calculate.
