System Size Overview
Balcony solar systems typically range from 200W to 800W. The most common sizes are 400W and 800W:
- 400W System: Usually 2 × 200W panels, ideal for small apartments and low energy consumption
- 800W System: Usually 4 × 200W panels, maximizes energy production for larger homes
- Installation: Both sizes can be DIY-installed, though 800W may require professional electrical connection
Both sizes are legal in all US states, though local regulations and utility interconnection requirements may vary.
ROI Comparison: 400W vs 800W
Under the same conditions (city, orientation, self-consumption), here are the typical differences:
Example Calculation (New York, South-facing, 70% self-consumption, $0.13/kWh):
| System Size | Annual Yield | Annual Savings | Payback Period |
|---|---|---|---|
| 400W | ~280 kWh | ~$25 | ~6.0 years |
| 800W | ~560 kWh | ~$51 | ~5.9 years |
* Investment: $800 (400W) vs $1,500 (800W), assumptions: PVGIS data, 14% system losses, 30% federal ITC applied
When Does 400W Make Sense?
- Small apartments or studios with limited space
- Low electricity consumption (under 500 kWh/month)
- Self-consumption < 50% (e.g., not home during the day)
- Tight budget ($800 vs $1,500 investment)
- Limited balcony or mounting space
- Rental property where you may move soon
When Does 800W Make Sense?
- Larger homes (3+ bedrooms) or high electricity consumption
- Self-consumption > 60% (home office, daytime appliance use)
- Higher electricity rates ($0.15+/kWh)
- Planning for future EV charging or heat pump
- Sufficient balcony space and mounting options
- Long-term home ownership (5+ years)
Tip: Calculate your individual ROI with our free calculator for your city and orientation.