Solar Panels Calculator
How many solar panels do you need? Enter your daily units or system size (kW) — the number of panels, roof area and total DC capacity will be calculated instantly.
Default calculation: one 580W panel in Pakistan produces about 2.3 kWh (units) per day. You can also edit the generation and roof area values yourself.
How to use
- Select the mode: if you know your daily units (kWh), use Mode A; if the system size (kW) is already decided, use Mode B.
- In Mode A, enter daily units — dividing your monthly bill by 30 is an easy way to find this.
- Panel wattage defaults to 580W; if you are using a different panel, enter its rating.
- You can edit the generation-per-panel and roof-area-per-panel values based on your city and roof.
- Check the results for panel count, DC capacity, roof area and expected daily/monthly generation.
Notes & FAQ
How much electricity does one 580W panel make per day?
In Pakistan, with about 4 effective sun hours: 580W x 4 hours = 2.32 kWh, i.e. about 2.3 units per day. It can be lower in winter and higher in summer.
Why is roof area 28 sq ft per panel?
A large panel is about 18-20 sq ft in size, but for planning, 28 sq ft per panel is a safe estimate including spacing between rows, shadow gaps and walking space.
Why is the panel count always rounded up?
Half a panel cannot be installed, so the required count is always rounded up to the next full number. This makes the actual DC capacity slightly higher than your requirement, which helps cover losses.
How do I keep generation from dropping over time?
Dust can quietly cut output by 10 to 25 percent. Use our Solar Panel Cleaning Savings Calculator to see how much regular cleaning saves you.