Live Demo — Solar Energy Yield Calculator
Enter installed capacity, peak sun hours and performance ratio to estimate the daily and annual energy your array will produce.
Solar Energy Yield Calculator
Free professional solar energy yield calculator for solar lighting systems. Input installed capacity in kWp, local peak sun hours and the system performance ratio (PR) to estimate daily, monthly and annual energy production, optionally compare it against a daily load to confirm the system can self-balance with battery storage.
Key Features
PV System Parameters
Set installed capacity in kWp (for example, 2 modules × 550W ≈ 1.1 kWp) and local peak sun hours.
Performance Ratio
Model all system losses - degradation, temperature, soiling, wiring and inverter/controller losses - with one PR value (typically 70-85%).
Daily Yield
Estimate the energy produced per day in kWh from installed capacity, PSH and PR.
Monthly & Annual Yield
Scale the daily figure to 30-day months and 365-day years for a full-year energy view.
Load Matching
Optionally enter a daily load in kWh to check the surplus (E_day - E_load) and confirm self-balancing.
Yield Quick Reference
Built-in table shows daily and annual yield for common installed capacities at PSH = 4.5h and PR = 75%.
Technical Specifications
| Platform | HTML5 Web App | Android (via WebView) |
| Core Calculation | E_day = P_rated × PSH × PR; E_year = E_day × 365 |
| Installed Capacity | 0.01 - 1000 kWp |
| Peak Sun Hours | 0.1 - 24 h/day |
| Performance Ratio | 30% - 100% (new system ~80%, aged ~75%) |
| Daily Load Energy | 0 - 1000 kWh/day (0 = yield only) |
| Calculation Period | Daily, monthly (30 days), annual (365 days) |
| Industry Standards | IEC 61724-1, IEC 61853-1 |
| Output | Daily / monthly / annual yield (kWh) + daily surplus against load |
Frequently Asked Questions
How is solar energy yield calculated?
Daily yield multiplies installed capacity by peak sun hours and performance ratio: E_day = P_rated × PSH × PR. Monthly yield is E_day × 30 and annual yield is E_day × 365. A 0.4 kWp array with PSH = 5h and PR = 0.75 produces 0.4 × 5 × 0.75 = 1.5 kWh/day and about 547 kWh/year.
What is the Performance Ratio (PR)?
PR is the overall system efficiency that accounts for temperature, wiring, inverter/controller and other losses; street-lighting systems typically run at 0.7-0.8. A new system is about 0.8, drops to about 0.75 after one year, and well-maintained systems hold 0.75-0.8. Module output falls roughly 4-5% for every 18°F (10°C) temperature rise.
Why is peak sun hours used instead of daylight hours?
Daylight lasts many hours, but irradiance is low in the morning and evening. PSH represents the number of hours of full 1000 W/m² irradiance equivalent, which is what actually drives generation. Using PSH in the yield formula gives accurate energy estimates without complex irradiance modeling.
What does the load matching surplus mean?
The daily surplus is E_surplus = E_day - E_load. A positive surplus means the array generates more than the daily load, so with battery storage the system can self-balance and recharge. A negative value means the array is too small for the load and the design needs more capacity.
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