How to Choose the Right Size Solar Generator (Step‑by‑Step Guide)
Choosing the right size solar generator can be confusing — but it doesn’t have to be.
This guide walks you through calculating your power needs, understanding battery capacity, inverter size, solar input, and matching everything to real products.
Step 1: Identify Your Power Needs
Start by listing the devices you want to run and how long you plan to use them.
Common Device Power Usage
| Device | Average Watts | Hours per Day | Total Wh |
|---|---|---|---|
| Mini Fridge | 60W | 8h | 480Wh |
| LED Lights | 10–20W | 4h | 40–80Wh |
| Laptop | 50–70W | 3h | 150–210Wh |
| Phone Charging | 5–10W | 2h | 10–20Wh |
| CPAP Machine | 30–60W | 8h | 240–480Wh |
Example Calculation
Fridge (60W × 8h) = 480Wh
Lights (20W × 4h) = 80Wh
Laptop (60W × 3h) = 180Wh
Total Daily Usage = 740Wh
Step 2: Calculate Required Battery Capacity
Solar generators lose some energy due to inverter and charging inefficiencies.
Use this simple formula:
Daily Wh × 1.2 = Recommended Battery Size
Example:
740Wh × 1.2 = 888Wh → choose a 1000Wh generator
Step 3: Consider Inverter Size (Continuous & Surge)
The inverter determines what devices you can run at the same time.
| Device | Continuous Watts | Surge Watts |
|---|---|---|
| Fridge | 60W | 120W |
| Coffee Maker | 800W | 1200W |
| Microwave | 1000W | 1500W |
| Power Tools | 600–1200W | 1200–2400W |
Rule of thumb:
Choose a generator with 20–30% more inverter power than your highest load.
Step 4: Choose Solar Input Size (Charging Speed)
Solar input determines how fast your generator recharges.
| Battery Size | Solar Input | Charging Time |
|---|---|---|
| 500Wh | 100W | 6–7 hours |
| 1000Wh | 200W | 6 hours |
| 1500Wh | 400W | 4–5 hours |
| 2000Wh | 600W | 4 hours |
Tip:
If you camp or live off‑grid, choose a generator with at least 300–600W solar input.
Step 5: Match Your Needs to Real Products
Small Needs (Phones, Lights, Laptops)
- 300–500Wh battery
- 300W inverter
- 100–200W solar input
Medium Needs (Fridge, CPAP, Tools)
- 700–1200Wh battery
- 700–1200W inverter
- 200–400W solar input
Large Needs (RV, Off‑Grid, Emergency Backup)
- 1500–3000Wh battery
- 1500–3000W inverter
- 400–1200W solar input
Recommended Solar Generators
Jackery Explorer 1000
- 1002Wh battery
- 1000W inverter
- 200W solar input
EcoFlow River 2 Pro
- 768Wh battery
- 800W inverter
- 940W solar input (X‑Boost)
Bluetti EB70S
- 716Wh battery
- 800W inverter
- 200W solar input
FAQ
How big of a solar generator do I need to run a fridge?
Usually 700–1000Wh with a 600–1000W inverter.
Can a solar generator power a house?
Only large units (2000–5000Wh) can run essential circuits.
How many solar panels do I need?
Divide battery size by panel wattage.
Example: 1000Wh ÷ 200W = 5 hours of sun needed.
Final Recommendation
If you want the simplest method:
- Add up your daily Wh
- Multiply by 1.2
- Choose a generator with enough inverter power
- Make sure solar input is fast enough