Factory Solar System Estimator
Enter your monthly electricity bill or units to see what size solar plant your factory needs, how much roof it takes, and how fast on-grid and off-grid systems pay back.
Solar on-grid vs off-grid
Plant size, roof area, savings and payback for your factory.
Bill total divided by units, taxes included.
Assumptions
Indicative starting values. Change them to match your site and installer quotes.
5 to 5.5 in most of Pakistan.
Share used 9am to 5pm.
Credit for surplus units.
Enter your monthly bill or units to size a solar plant.
How this is calculated
- 1
Daily consumption
Your monthly units, or your bill divided by the average cost per unit, spread over 30 days.
- 2
Plant size
Daily units divided by sun hours and a 78% performance ratio, which covers heat, dust, inverter and cable losses. In most of Pakistan a 1 kW plant makes about 4 units a day.
- 3
On-grid savings
Units you use during the day save your full tariff. Surplus units exported to the grid are credited at the lower export rate, so a factory that runs mainly in daylight saves the most.
- 4
Off-grid batteries
The night share of your usage is stored in lithium batteries at 90% depth of discharge, with about 13% lost charging and discharging, which needs slightly more panels.
- 5
Roof area and payback
About 70 sq ft of roof per kW with modern 585 W panels and walking space. Payback is the system cost divided by the monthly saving.
Frequently asked questions
How many units does 1 kW of solar make in Pakistan?
Roughly 4 to 4.5 units a day on average, or about 1,400 to 1,600 units a year, depending on city, panel angle, dust and summer heat.
On-grid or off-grid for a factory?
On-grid is cheaper and pays back faster when you have a reliable grid connection and run mostly in the day. Off-grid or hybrid makes sense where load-shedding stops production or the grid connection is weak.
How much roof space do I need?
Plan on about 70 square feet per kW on a flat roof, including gaps for cleaning and shade between rows. A 100 kW plant needs around 7,000 square feet.
Is net metering still available?
Exported units are credited under your distribution company's current net-metering or net-billing terms, and approval is limited to your sanctioned load. Check the current export rate with your installer and enter it in the calculator.