Why Load Calculation Matters Before Buying Solar

How a Customer Can Decide Which Solar System Is Suitable

The easiest way to understand which solar system is suitable for you is to evaluate three things:
your monthly electricity bill, your appliance load, and whether you need battery backup.
A family using only fans, lights, LED TV, and a refrigerator usually needs a smaller setup than a household running one or two air conditioners,
water pump, washing machine, and kitchen appliances.

In Pakistan, many customers ask, “Should I install a 5kW solar system or 8kW solar system?”
The answer depends on both daytime usage and future expansion. If you are planning to add more ACs, shift more load to solar,
or install a battery later, it is usually better to keep a safety margin.

Step 1: Make a List of All Appliances

Start by listing every appliance you want to run on the solar system. This includes lights, fans, refrigerator, television, washing machine,
computer, air conditioner, water pump, microwave, and any other electrical equipment. For each appliance, note the wattage,
quantity, and daily usage hours.

Step 2: Calculate Daily Energy Consumption

Use this formula for each appliance:

After calculating each item separately, add all values together to get total daily consumption.
This number shows how much energy your solar system needs to produce every day.

Step 3: Estimate the Required Solar System Size

Once total daily energy consumption is known, divide it by average peak sunlight hours.
In most cities of Pakistan, practical solar design usually considers around 5 to 5.5 peak sun hours.
Also include efficiency losses due to dust, heat, wiring, inverter losses, and weather conditions.

Example:

This means the minimum calculated requirement is around 2.5kW. However, in real-life installations,
customers should keep margin for cloudy weather, load fluctuation, panel degradation, and future expansion.
That is why the practical recommendation for this example becomes:

Step 4: Decide If You Need On-Grid, Hybrid, or Off-Grid Solar

Step 5: Battery Backup Calculation

If you want backup at night or during load shedding, battery selection becomes very important.
The required battery capacity depends on how many appliances you want to run and for how long.

Example:

Since batteries should not be fully discharged, a margin should always be added.
Lithium batteries are more efficient, offer better depth of discharge, charge faster, and last longer than lead-acid batteries.
However, lead-acid or dry batteries may still be considered for lower-budget systems.

Step 6: Inverter Sizing

Inverter capacity should be based on the total running load and startup surge of heavy appliances.
Air conditioners, refrigerators, and water pumps require special attention because their starting current may be much higher than normal running watts.

• Example Running Load: AC (1,200W) + Fridge (200W) + Fans (320W) = 1,720W
• Surge Margin: Startup of compressor-based appliances can be significantly higher
• Recommended Inverter: 5kW Hybrid Inverter for better flexibility and future expansion

Step 7: Number of Solar Panels Required

If you use modern high-wattage panels such as 550W modules, the approximate number of panels can be estimated like this:

Quick Load Scenarios for Pakistani Customers

Which Solar System Is Best for You?

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Important Tips Before Finalizing Your Solar System

• Always keep 15% to 25% extra margin for system losses and future expansion.
• If load shedding is common in your area, choose a hybrid solar system with lithium battery.
• If your goal is bill reduction only, on-grid solar with net metering may be the best solution.
• Use quality solar panels, reliable inverter brands, and professional installation for long-term results.
• Check available roof space before deciding between 3kW, 5kW, 8kW, or 10kW systems.