Solar Panel Installation Calculator
Calculate solar panels and kWp required.
The Solar Panel Installation Calculator is a free tool designed for construction professionals and enthusiasts. Calculate solar panels and kWp required. Instantly get the required materials broken down by purchase units, with an option to add a wastage allowance so you never run short on site.
Inputs
Result
Result
How to Use This Calculator
- Determine the total circuit power in watts (W) or kilowatts (kW).
- Measure the total cable run in meters (outward + return).
- Enter the installation voltage (230 V single-phase or 400 V three-phase).
- Enter the maximum allowable voltage drop (max 3 % residential, 5 % industrial).
- Click 'Calculate' to get cable cross-section, current and actual voltage drop.
Frequently Asked Questions
Per standard regulations, the maximum voltage drop is 3 % for residential and lighting circuits and 5 % for other uses.
General-purpose outlet circuits use 2.5 mm² cable; large appliance circuits use 4 mm². Lighting circuits use 1.5 mm².
If the circuit feeds wet areas (bathroom, kitchen, outdoor) or equipment with higher contact risk, a high-sensitivity RCD (30 mA) is mandatory.