☀️ Solar System Size Calculator
Select only the appliances you actually use — day load on solar panels, night load on battery — get instant solar panel size, battery AH, inverter rating and cost estimate
✓ Lightweight ✓ Safe ✓ Fast charge
✓ Maintenance-free ✓ Common
✓ Available everywhere in Pakistan
✗ Requires monthly maintenance
Solar System Size Calculator Pakistan — Day Load vs Night Load Explained
When I visited a solar dealer for a quote, every vendor asked the same question: how much load do you have? I said two fans, ten LED lights, a refrigerator and no AC. They immediately quoted a 5kW system. The problem was that my refrigerator runs all night on battery, my fans run eight hours a day on solar, and the lights split between day and evening. These are completely different sizing calculations. No generic calculator was separating them. This tool does exactly that — daytime load determines your solar panel size, nighttime load determines your battery size. They are independent calculations and must be treated separately.
Why Day and Night Load Must Be Calculated Separately
A solar system has two energy sources: solar panels during daylight and battery storage at night. When you run an air conditioner only during the day, it draws energy directly from the solar panels and has no impact on battery sizing whatsoever. If you add that AC load to a single combined calculation, the calculator will dramatically oversize your battery bank. Conversely, appliances running through the night determine how large your battery bank must be but have minimal effect on panel sizing since the panels simply need to generate enough to charge the battery during the day. This calculator separates both sections so each is sized correctly for its actual energy source.
How Solar Panel Size Is Calculated
Solar panel capacity is based on total daily energy consumption including both day and night loads, because your panels must generate enough electricity to power daytime appliances directly and also recharge the batteries for nighttime use. The formula is: Solar kW = Total Daily Wh divided by (Peak Sun Hours x System Efficiency x 1000). For Pakistan with 5 peak sun hours and 80% system efficiency, a home consuming 10,000 Wh per day needs 10,000 divided by (5 x 0.80 x 1000) = 2.5 kW of solar panels. Adding a 20% safety buffer gives 3 kW, which is 8 panels of 380W each.
How Battery AH Is Calculated
Battery sizing is based exclusively on your nighttime load and the number of backup hours you require. The formula is: AH = Night Load in Wh divided by (Battery Voltage x Depth of Discharge). For a lithium battery with 80% DoD, a 48V system powering 2000 Wh of nighttime load over 8 hours total (250W average): AH = 2000 divided by (48 x 0.80) = 52 AH. This calculator applies this correctly using only the night section, not the combined load.
Lithium vs Dry Battery vs Lead Acid — Pakistan 2026 Comparison
Lithium iron phosphate (LiFePO4) batteries are now widely available in Pakistan and represent the best long-term value. With 80% depth of discharge, a 200AH lithium battery delivers 160AH of usable capacity. Lifecycle of 3,000 to 6,000 charge cycles translates to 10 to 15 years of service. A 48V 200AH lithium bank costs approximately Rs 280,000 to Rs 350,000.
AGM and gel dry batteries offer a middle ground at 60% DoD and 5 to 7 years of life. They are fully sealed and maintenance-free. A comparable 48V 200AH AGM bank costs approximately Rs 120,000 to Rs 180,000.
Tubular lead acid batteries are the cheapest upfront at Rs 60,000 to Rs 90,000 for a comparable bank, but allow only 50% DoD and require monthly distilled water top-ups. With 3 to 5 year lifespan, replacing lead acid twice over ten years typically costs more than buying lithium once.
Hybrid Solar System — The Best Choice for Pakistan 2026
A hybrid solar system connects solar panels, a battery bank and the WAPDA grid to a single hybrid inverter. During daylight the inverter prioritizes solar power for your load and simultaneously charges the batteries. At night it draws from the batteries. If batteries run low, it seamlessly switches to grid power. NEPRA's net metering policy allows hybrid systems to export excess solar generation to the grid, which DISCOs credit against future bills. For most urban homes in Pakistan, hybrid delivers the best combination of load shedding protection, bill reduction and investment return.
Inverter Sizing
Your inverter should be sized at 1.25 to 1.5 times your peak simultaneous load. Air conditioners and water pumps draw two to three times their rated power during startup, which the inverter must handle without tripping. For a home with a 1.5 ton AC (1500W) and 500W of other simultaneous load, peak can reach 4500W during AC startup. A 5kVA inverter handles this safely. Popular hybrid inverter brands in Pakistan include Growatt, Deye, Solis, Luxpower and Inverex.
Solar Panel Selection
Pakistan's solar market in 2026 is dominated by monocrystalline panels ranging from 380W to 550W per panel. A 380W panel is the most widely available and priced at approximately Rs 10,000 to Rs 13,000 per panel. Half-cut 450W panels improve shade tolerance and are worth the small premium. Bifacial 550W panels generate additional power from rear-side reflected light and suit open rooftop installations in Sindh and Balochistan where ground reflectance is high. All panel prices have dropped significantly over the past three years, making larger systems increasingly cost-effective.
Select your daytime appliances above, then separately select your nighttime appliances. Adjust quantity and daily usage hours for each. Choose your battery type and system settings, then calculate your complete solar system plan in one click.
