Inputs
Example Data Table
This sample shows typical assumptions for a mid-size site installation.
| Input | Example value | Unit | Notes |
|---|---|---|---|
| System size | 50 | kWp | Rooftop or site office load support |
| Peak sun hours | 5.2 | kWh/m²/day | Representative annual average |
| Base performance ratio | 82 | % | Design quality and equipment selection |
| Inverter efficiency | 97.5 | % | Modern string inverter performance |
| Availability | 99 | % | Planned maintenance and faults |
| Average cell temperature | 45 | °C | Higher temperature reduces output |
| Shading loss | 3 | % | Temporary obstructions and structures |
| Soiling loss | 2 | % | Dust and cleaning frequency |
Formula Used
This calculator uses a practical yield model suitable for early design and construction planning:
- Equivalent PSH = Annual Irradiation ÷ Days, or directly entered as daily PSH.
- Temperature factor = 1 + (TempCoeff/100) × (CellTemp − 25).
- Loss factor = Π(1 − loss%/100) across selected losses.
- Total performance factor = (BasePR/100) × (InverterEff/100) × (Availability/100) × TemperatureFactor × LossFactor.
- Daily Energy (kWh) = kWp × PSH × TotalPerformanceFactor.
- Annual Energy (kWh) = DailyEnergy × DaysPerYear.
- Lifetime Energy uses compounded annual degradation.
For bankable studies, replace averages with hourly simulation and measured meteorological data.
How to Use This Calculator
- Enter the system size in kWp for the planned PV array.
- Select irradiation mode and provide either daily PSH or annual irradiation.
- Set base performance ratio, inverter efficiency, and expected availability.
- Adjust temperature coefficient and average cell temperature for your climate.
- Add loss percentages for shading, soiling, mismatch, and wiring as needed.
- Click Calculate to view results above the form.
- Use the CSV or PDF buttons to share results with stakeholders.
PV Energy Yield Planning Notes
1) Start with site solar resource
Use average peak sun hours (PSH) when you only have a quick resource estimate. Typical annual averages range from 3.0 to 7.0 kWh/m²/day depending on latitude, cloud cover, and dust. If you have annual plane-of-array irradiation, convert it to an equivalent PSH by dividing by 365. This keeps the yield model consistent across projects.
2) Apply a realistic performance ratio
For preliminary construction planning, a base performance ratio of 0.75–0.85 is common for well-designed systems. Inverter efficiency is often 96–99%, while availability is typically 98.5–99.5% if maintenance access is planned. Combine these with explicit losses (shading, soiling, wiring, mismatch) to avoid overestimating annual energy.
3) Temperature can shift output materially
Module power commonly drops as cell temperature rises above 25°C. Many crystalline modules have temperature coefficients between −0.30 and −0.45% per °C. On hot sites where average cell temperature can reach 45°C, this can reduce yield by roughly 6–9% before other losses. Use site ventilation and mounting strategy to manage heat.
4) Loss assumptions should match construction realities
Temporary shading from cranes, scaffolding, and adjacent works can add 1–5% losses, while persistent obstructions may exceed 10%. Soiling losses of 1–4% are common in dusty environments without frequent cleaning. Wiring and mismatch losses are often 0.5–2% each. Document every assumption so the team can revise it as layout and schedules change.
5) Use lifetime yield for long-term decisions
Degradation for modern modules is often 0.3–0.8% per year after initial stabilization. Over a 25-year horizon, compounding degradation can reduce cumulative energy by several percent compared with a constant-output assumption. Pair the lifetime kWh with tariff and emissions factors to compare options such as higher-quality modules, improved O&M access, or cleaning plans. Record chosen inputs and keep them aligned with commissioning tests, maintenance logs, and metered production.
FAQs
1) What is PV energy yield in this calculator?
It is the estimated electrical energy produced over time, calculated from system size, site irradiation, and a combined performance factor that represents temperature effects and operational losses.
2) Should I use daily PSH or annual irradiation?
Use daily PSH for quick planning. Use annual irradiation when you have verified plane-of-array data; the tool converts it into an equivalent daily value for consistent calculations.
3) Why does cell temperature matter more than ambient temperature?
Modules run hotter than air due to solar loading. The power rating is referenced to 25°C cell temperature, so hotter cells reduce output according to the temperature coefficient.
4) What losses are most important on construction sites?
Temporary shading, soiling from dust, and downtime for access restrictions are common. Wiring losses can increase when cable routes are long or repeatedly modified during staging.
5) How can I validate the results?
Compare the annual specific yield (kWh/kWp/year) against similar local projects, then refine inputs using measured irradiation, inverter logs, and meter readings after commissioning.
6) What does capacity factor mean here?
Capacity factor is annual energy divided by the energy the system would produce at full rated power all year. It helps compare sites and designs independent of system size.
7) How is lifetime energy computed?
The calculator applies an annual degradation rate to the first-year energy and sums the reduced output across the selected project horizon, providing a practical lifetime kWh estimate.