✨ Introduction: Why Proper Sizing Matters
Installing a solar system that’s too small may not cover your energy needs. A system that’s too large could lead to wasted investment. That’s why it’s important to size your solar setup correctly — especially in Europe, where electricity prices, sunlight hours, and subsidy programs vary across countries.
This 2025 guide provides a practical method to size your solar system in kWh, including power generation estimates, battery pairing tips, and common usage examples for EU households.
📊 1. Step-by-Step: Estimate Your Home’s Energy Use
Start with your monthly energy bill, which usually lists total kWh consumed. If not, use the formula:
Monthly Usage (kWh) = Average Daily Use (kWh) × 30
| Appliance | Average Daily Use (kWh) | Monthly (kWh) |
|---|---|---|
| Refrigerator | 1.2 | 36 |
| Washing Machine | 0.5 | 15 |
| TV (LED, 40″) | 0.3 | 9 |
| Laptop/Computer | 0.6 | 18 |
| Lighting (LEDs) | 0.8 | 24 |
| Heat Pump / Heater | 3.5 | 105 |
| EV Charger (basic) | 6.0 | 180 |
| Total Example | — | 387 kWh |
🌟 2. Choose the Right System Size
To offset 80–100% of your electricity use:
Required kWh = Monthly Usage × 1.2 (buffer for cloud/weather losses)
Using the above example:
- 387 kWh × 1.2 = 464.4 kWh/month
- Daily generation target ≈ 15.5 kWh/day
Typical System Sizes:
| System Size (kW) | Daily Output (kWh) | Best For Homes Using… |
|---|---|---|
| 2 kW | 6–8 | 200–300 kWh/month |
| 3.5 kW | 11–14 | 300–450 kWh/month |
| 5 kW | 14–20 | 400–600 kWh/month |
| 6–8 kW | 20–30 | 600–900+ kWh/month |
📝 Tip: Adjust by your country’s sunlight hours. Spain gets 5.5/day, Germany 3.5–4.
🛠️ 3. Battery Storage Matching
If you want to store your solar power for nighttime or grid outages:
| Battery Size (kWh) | Hours of Backup Power | Covers… |
|---|---|---|
| 2.5 kWh | ~2–3 hours | Lights + WiFi + laptop |
| 5 kWh | ~4–6 hours | Lights + fridge + TV |
| 10 kWh | ~10+ hours | Most small homes |
| 15 kWh+ | Full day backup | Medium family homes |
🔋 Compatible products: EB2048 (5.12 kWh), EB10240 (10.24 kWh), stackable.
📚 4. DIY or Use a Calculator?
You can manually size your system using the above, or use free online calculators like:
- Solar Electricity Handbook Sizing Tool
- EnergySage EU Solar Calculator
Always validate your design with a certified installer if connecting to the grid.
🚀 Conclusion: Right Size = Maximum Efficiency
Sizing your solar system accurately helps you avoid overpaying or underperforming. With rising energy costs across Europe, a right-sized solar+storage system offers better ROI, comfort, and energy freedom.
📞 Want help sizing your system? Ask JYHSolar’s energy consultants or explore more tools in our solar blog.
