Solar Yield Estimation Calculator | P50/P90 Energy Production

P50 is the expected (median) annual production: in a typical weather year your solar system should produce around this amount. It is simulated from one reference year's hourly weather profile adjusted toward the five-year historical monthly average, a climate-adjusted reference-year simulation.

P90 is a conservative planning figure you can expect to be reached or exceeded in about 9 out of 10 weather years. It is derived from the inter-annual variability of solar radiation plus a system uncertainty (for example 5%), combined by root-sum-square and applied at 1.282 standard deviations. It is a statistical planning figure, not a lender-certified bankability assessment.

Multiply the installed capacity by the location's specific yield. A typical 10 kWp equator-facing system in most of Pakistan produces about 13,000 to 17,000 kWh per year (a specific yield of about 1,300 to 1,700 kWh per kWp per year, higher in the tropics and the south). The simulation returns the exact figure for your location, direction and tilt.

Face panels toward the equator for maximum annual output: south in the northern hemisphere and north in the southern hemisphere. A tilt close to your latitude is usually best, and the calculator recommends the angle automatically. East- or west-facing panels produce less annual energy but shift more generation into the morning or evening.

Typical system losses cover cables, inverter conversion, mismatch and availability, about 8% for a modern, well-built system (for example DC wiring 1.5%, AC wiring 1.0%, inverter 2.0%, mismatch 1.5%, availability 1.0%, other 1.0%). On top of that, the simulation adds an estimated temperature effect and your soiling assumption, all combined multiplicatively.

Soiling is the average annual production lost to dust, bird droppings or snow cover. The calculator defaults to moderate (2%), which suits most sites; in dry, dusty climates choose a high soiling level or enter an exact percentage. Washing the panels periodically reduces this loss.

The temperature coefficient (Pmax) is the percentage of power a panel loses for every degree Celsius above 25 degrees, for example -0.35%/C means 0.35% loss per degree. NOCT is the Nominal Operating Cell Temperature, the module's operating temperature under standard conditions, typically about 42 to 45 degrees C for modern panels. The simulation estimates module temperature hour by hour as ambient plus (POA/800) x (NOCT - 20).

Specific yield tells you how many kWh each 1 kWp of installed capacity produces per year at a location, for example 1,400 kWh/kWp. Multiplying it by the installed capacity gives the annual generation, which is why the same panels can perform differently in different cities.

This is a planning-grade estimate, not a guarantee. It uses five years of historical solar radiation and temperature data from Open-Meteo, runs one reference-year hourly tilted simulation, then corrects the result to the long-term monthly average. Five to six annual weather observations is a small sample for a financial-grade estimate, and the model does not simulate module failure, inverter outage or shading.