Solar Calculator
What Solar System Size Does Your Home Need in Pakistan?
Estimate the right solar system size for a Pakistani home using monthly units, daytime load, roof space, city conditions, and backup requirements.
Start with electricity units, not only rupees
A bill amount includes tariffs, taxes, fixed charges, adjustments, and other items that can change. Monthly kilowatt-hours, shown as units, are a more useful starting point for solar sizing.
Collect twelve months of bills and identify the high, low, and average consumption. A design based on one mild month may be too small for summer, while a design based only on the highest month may be unnecessarily large.
Separate daytime and nighttime use
Solar panels generate during daylight. A property that uses most electricity during the day can consume a larger share of its generation directly. A home with heavy nighttime use may need load shifting, battery storage, or a different financial expectation.
- List appliances normally running between morning and late afternoon
- Record air-conditioner quantity, capacity, and operating hours
- Identify pumps, motors, irons, ovens, and other high-power loads
- Separate essential outage loads from optional heavy loads
- Note weekday and weekend differences
Check roof area, shade, and structure
A calculation can recommend capacity that the roof cannot safely accommodate. Panel dimensions, orientation, shade from neighbouring buildings, water tanks, parapets, access paths, and structure design all affect the practical layout.
Do not remove safety access or crowd panels into shaded areas to reach a target number. A site survey should confirm usable area and assess the roof and mounting approach.
Capacity is not the same as backup power
System size in kW describes generation capacity, while battery storage is measured in energy capacity, commonly kWh. Backup duration depends on usable battery energy and the connected load.
Define a backup circuit and list what must stay on during an outage. Fans, lights, internet, refrigerator, and selected sockets usually need a different storage plan than multiple air-conditioners or water pumps.
Use a calculator, then validate the design
GreenOH’s calculator can turn bill and location inputs into a planning estimate for system size, potential savings, and payback. It is useful for shortlisting packages and preparing better questions for installers.
The final system should still be validated through bills, load profile, roof survey, connection details, equipment limits, current regulations, and a written itemised quote.
Frequently asked questions
Can I size solar from my monthly bill amount?
The bill is a starting point, but monthly units are more useful than rupees. Review twelve months and separate daytime from nighttime consumption.
How many solar panels does my home need?
Panel count depends on target system capacity, each panel’s wattage, roof layout, shading, inverter limits, and the final electrical design.
Should I size solar for my highest summer bill?
Not automatically. Compare annual consumption, daytime use, roof limits, budget, and expected future loads. Ask for monthly production and consumption scenarios.
Does a larger solar system provide longer backup?
Not by itself. Backup duration mainly depends on usable battery capacity, connected loads, inverter capability, and available solar generation during the outage.