Solar Panel System
15 panels (585 W each) · 8.78 kW installed · PKR 675,675
Panels Needed
15 panels
585 W each · 8,775 W installed · 8.78 kW
Daily Gen
37.3 kWh
Monthly Gen
1,135 kWh
Annual Gen
13,622 kWh
System Cost
PKR 675,675
Monthly Savings
PKR 56,761
Annual Savings
PKR 681,077
Payback Period
1.0 years
Oversized for losses: 8,235 W of panels installed for your 7,000 W target (system type Grid-tied — ~85% efficiency).
Payback Timeline
Cumulative savings (green) crosses system cost (red dashed) at the payback point. Everything above the red line after that is pure profit.
Monthly Generation (seasonal)
Estimated monthly output accounting for seasonal sun variation in Pakistan. Summer months generate ~20% more than winter.
Cost Breakdown
10-Year Value
Most quality panels are warrantied for 25 years of output. After payback, everything is profit. Rising electricity tariffs make real savings even higher.
Step-by-step calculation
Formula
Panels = Ceil(System W ÷ Efficiency ÷ Panel W). Daily Gen = Installed kW × Sun Hours × Efficiency. Payback = Total Cost ÷ Annual Savings.
- 1Target system size: 7 kW = 7,000 W AC output
- 2System type: Grid-tied (no battery) → overall efficiency 85%
- 3Required panel capacity = 7,000 ÷ 0.85 = 8,235 W DC
- 4Chosen panel: 585 W each
- 5Panels needed = ⌈8,235 ÷ 585⌉ = 15 panels
- 6Total installed = 15 × 585 = 8,775 W (8.78 kW)
- 7━ Generation ━
- 8Daily kWh = 8.78 × 5 hrs × 0.85 = 37.29 kWh
- 9Monthly ≈ 37.29 × 30.44 = 1,135 kWh
- 10Annual ≈ 37.29 × 365.25 = 13,622 kWh
- 11━ Cost ━
- 12Panel cost = 8,775 W × PKR 55 = PKR 482,625
- 13Installation overhead (40%) = PKR 193,050
- 14Total system cost = PKR 675,675
- 15━ Savings & Payback ━
- 16Monthly savings = 1,135 kWh × PKR 50/kWh = PKR 56,761
- 17Annual savings = PKR 681,077
- 18Payback period = PKR 675,675 ÷ PKR 681,077/yr = 1.0 years