Solar guide
How many solar panels do I need?
Calculate panel count from system size, panel wattage, electricity use and available roof space.
The number of solar panels you need depends on the target system size and the wattage of each panel. Higher-wattage panels reduce the number of panels required for the same system size. See the methodology page for the formula.
Panel count calculator
Enter your target solar system size and panel wattage.
Estimated panels needed
Allow extra roof space for setbacks, access paths and obstacles.
Open full calculatorPanels needed = target system size kW × 1000 ÷ panel wattageCommon panel counts by system size
| System size | With 400W panels | With 430W panels |
|---|---|---|
| 3 kW | 8 panels | 7 panels |
| 5 kW | 13 panels | 12 panels |
| 6 kW | 15 panels | 14 panels |
| 10 kW | 25 panels | 24 panels |
What affects the number of panels?
- Your target system size in kW.
- The wattage of each panel.
- Roof area and usable roof shape.
- Shading, orientation and roof pitch.
- Local grid export limits or inverter size limits.
- Whether you want to cover full usage or only part of your bill.
Panel count FAQ
How many panels are needed for 5kW?
With 430W panels, a 5kW system usually needs about 12 panels.
Do higher-wattage panels save roof space?
Usually yes. Higher-wattage panels can reach the same system size with fewer modules.
Should I cover 100% of my electricity usage?
Not always. The best size depends on self-consumption, export tariffs, roof space and local rules.
Does panel count equal usable output?
No. Output also depends on sunlight, orientation, shading, temperature and system losses.