How to Calculate the Perfect Solar System Size for Your Home

How to Size a Solar System Correctly

Under-sizing your solar system leads to reliance on expensive grid power, while over-sizing leads to unnecessary capital expenditure. Calculating the exact kilowatt (kW) requirement of your residence is a structured engineering process.

Step 1: Analyze Your Monthly Consumption

Look at your electricity bills for the last 12 months. Find the billing month with the highest electricity consumption in kilowatt-hours (kWh or units). For most Pakistani homes, this is June, July, or August due to air conditioning load.

Step 2: Calculate Daily Average Units

Divide your peak monthly units by 30. For example, if your peak monthly consumption is 1,200 units:

1200 units / 30 days = 40 units per day

Step 3: Factor in Solar Generation Hours

On average, Pakistan receives about 4.5 to 5 hours of effective peak sunlight per day. To generate 40 units per day, divide the daily average units by solar generation hours:

40 units / 4.5 hours = 8.88 kW system size

In this case, a 10 kW solar system would be the most suitable recommendation, providing comfortable headroom for cloudy days and transmission line losses.

Connecting to the Load Calculator

If you do not have your billing history, you can estimate your load based on current appliances. Compile your list of air conditioners, water pumps, refrigerators, and fans, and use the TechnoKraft Load Calculator to run a simulation instantly.