Solar Panel Calculator – Load & System Size
List your appliances to get the solar array, inverter and battery size you need.
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Worked example
Example: four fans, six LED bulbs, a refrigerator, a 1.5-ton inverter AC for 6 hours and a TV, with 5 peak sun hours and 25% losses.
| Daily energy use | 12.83 kWh |
|---|---|
| Solar array | 3.42 kW (7 × 550 W panels) |
How the Solar Panel Calculator – Load & System Size works
List your appliances with watts, quantity and daily hours. The calculator totals daily energy, divides by peak sun hours after losses to size the solar array, and sizes the inverter and battery.
Formula: Array kW = Daily kWh ÷ (Peak sun hours × (1 − losses))
What to know before you calculate
Pakistan receives about 5 to 6 peak sun hours a day in most regions, which is the figure behind the default. Heavy loads such as ACs and water pumps drive both panel and inverter size.
How the size of a solar system is worked out
A solar system has to replace the energy you use in a day. Add up every appliance as watts × quantity × hours of use, which gives watt-hours per day. Divide that by the usable sun your roof gets (peak sun hours) after allowing for losses in the panels, wiring and inverter. The answer is the size of the panel array in kilowatts.
Most of Pakistan receives roughly five to six peak sun hours on a clear day, but winter, fog, dust and cloud lower this. This calculator assumes 5 hours and 25% total losses, which is a cautious starting point. You can change both numbers.
Choosing the inverter
The inverter must carry everything that can run at the same time, so the calculator uses your connected load plus a 25% margin. Motors in air conditioners, refrigerators and water pumps draw several times their running power for a moment when they start. If you run a large AC or pump, ask the installer for an inverter rated for that surge, and check that a hybrid inverter can handle it.
Grid-tied, hybrid or off-grid
A grid-tied system has no battery and sends spare power to the grid under a net-metering agreement with your distribution company. A hybrid system adds batteries so you have power during load-shedding. An off-grid system works without the grid at all and needs the largest battery bank. The battery figure shown here is for the backup hours you enter, not for a whole night of full use. Net-metering rules and buy-back rates have changed over time, so confirm the current terms with your distribution company before you decide.
Roof and installation tips
Panels in Pakistan face south and are usually tilted at about the same angle as your latitude. Keep them out of shade from tanks and neighbouring buildings, because even partial shade cuts output sharply. Panels also lose output when dusty, so plan to clean them. Use this result to compare quotes: ask each installer for the panel brand and wattage, the inverter model, the battery type, the warranty and what is covered if the grid connection is delayed.
Tips for accurate results
The system-losses field already allows for wiring, heat and dust, so do not add another margin on top. Add only appliances you really plan to buy later, and ask installers to quote the same array size so you can compare offers.
Roman Urdu mein
Ghar ke appliances ke watts aur ghantay daalein to solar panels, inverter aur battery ka andazan size mil jata hai.
Frequently asked questions
Can solar run an AC all day?
Only with a large array and batteries or grid support. Size the system on the hours you actually need.
How many solar panels do I need?
Divide your array size in watts by the panel wattage, e.g. 5 kW ÷ 550 W ≈ 10 panels.
What inverter size do I need?
Pick an inverter with at least 125% of your maximum simultaneous load.
Can I use this result as a quotation?
No. It sizes a system from the figures you enter. A real quote also depends on roof space, shade, the panel and inverter brand and installation costs, so compare several installers.
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Disclaimer: results are estimates for general information. Confirm figures with the official authority, bank, institution or a qualified professional.