Solar System Size (kW) Requirement Calculator 2026

Choosing the right solar system size is the most critical step in your transition to renewable energy. A system that is too small won't cover your bills, while one that is too large may result in a longer ROI period due to lower export rates.

Step 1: Inventory Your Load

The first step is to list all the appliances you intend to run on solar. For each appliance, you need to know:

• Wattage: The power it consumes (found on the sticker behind the appliance).
• Quantity: How many of these you have.
• Usage Hours: How many hours per day you run them.

Step 2: Calculate Daily Energy (kWh)

Multiply the wattage by quantity and hours for each appliance, then sum them up. Divide by 1000 to get the daily units (kWh) required.

Step 3: Account for Losses

Solar systems aren't 100% efficient. Inverters, wiring, and dust on panels can reduce efficiency by 15-25%. Our calculator uses an 80% efficiency factor by default.

Step 4: The Peak Sun Hours Rule

The energy produced depends on the intensity and duration of sunlight. In Pakistan, we are blessed with high irradiance, averaging 5.5 peak sun hours.

Formula: Required kW = Daily Units / (Peak Sun Hours × Efficiency)

Pro Tip for 2026

With the new fixed charges on net-metering in Pakistan, it is often better to size your system for 70-80% of your total load rather than 100%, especially if you don't have batteries. This maximizes self-consumption and avoids paying high fixed charges for a large connection.