Explicit checks passed
3 explicit checks passed for the entered values. This does not replace independent verification where the decision is safety-critical, contractual, statutory, financial or medical.
3 pass1 info
📊
Performance Ratio (PR)
Measured plant PR and specific yield per IEC 61724-1.
PerformanceCore inputs only — quick sizing with engineering defaults.
Inputs (SI units)
Signed — can be below 0 °C in cold climates.
Signed, typically negative — never enter as a positive number.
Results
✓ PASS — PR is below the 90% level typically associated with metering error.
✓ PASS — Measurement period ≥ 30 days gives a reasonably representative PR.
✓ PASS — Ground-based irradiance sensor used — good data quality basis.
Solar PV decision support
PV design decision summary
This section organises the existing calculator output into design checks, governing criteria and comparison cases. Core solar formulas and the calculator's original results are unchanged.
Governing criterion
Measured AC yield ÷ reference irradiation yield
83.3 %
PR compares measured AC specific yield with the plane-of-array reference yield over the same measurement interval.
Design checks
Solar engineering check 1
pass✓ PASS — PR is below the 90% level typically associated with metering error.
Structured directly from this solar calculator's own runtime alert.
Solar engineering check 2
pass✓ PASS — Measurement period ≥ 30 days gives a reasonably representative PR.
Structured directly from this solar calculator's own runtime alert.
Solar engineering check 3
pass✓ PASS — Ground-based irradiance sensor used — good data quality basis.
Structured directly from this solar calculator's own runtime alert.
Measured PR review
info83.3%
Use consistent AC energy and plane-of-array irradiation measurement intervals when trending PR.
Next design actions
Engine recommendation 1
POA-based PR is the IEC 61724-1-correct basis for this result.
Engine recommendation 2
Report PR alongside the measurement period and sensor type for auditability.
Engine recommendation 3
Engineering-grade preliminary calculation. Final design must be verified against project-specific site conditions, manufacturer datasheets, applicable standards and utility requirements.
Primary design output
83.3 %
Excellent
Measurement-quality check
Use synchronized AC energy and calibrated POA irradiation data
PR is only meaningful when energy and irradiation cover the same interval and the sensor/meter chain is reliable.
Scenario comparison
Lower and higher cases are recalculated by the same solar calculator engine. They are comparison cases, not weather forecasts or guaranteed production values.
Lower measured AC energy
measured AC energy = 1000
- Performance ratio
- 66.7 %
- Temperature-corrected PR
- 71.7 %
- Final (specific) yield Yf
- 100 kWh/kWp
- Reference yield Yr
- 150 h
Current inputs
measured AC energy = 1250
- Performance ratio
- 83.3 %
- Temperature-corrected PR
- 89.6 %
- Final (specific) yield Yf
- 125 kWh/kWp
- Reference yield Yr
- 150 h
Higher measured AC energy
measured AC energy = 1500
- Performance ratio
- 100 %
- Temperature-corrected PR
- 107.5 %
- Final (specific) yield Yf
- 150 kWh/kWp
- Reference yield Yr
- 150 h
Decision sensitivity
measured AC energy · up
For the same calculator engine, the lower case changes Performance ratio by -19.9% and the higher case by +20.0%.
This is a deterministic input sensitivity check, not a statistical uncertainty or weather forecast.
Methodology & limit
Decision support is structured from the existing solar calculator engine and the current user inputs. PASS/FAIL is shown only where the engine or entered project criteria support an explicit check. Final PV design still requires site survey, exact module/inverter datasheets, structural/electrical design and applicable statutory approval.
Engineering Recommendations
- →POA-based PR is the IEC 61724-1-correct basis for this result.
- →Report PR alongside the measurement period and sensor type for auditability.
- →Engineering-grade preliminary calculation. Final design must be verified against project-specific site conditions, manufacturer datasheets, applicable standards and utility requirements.
Detailed Calculation Log
Interpretation band: Excellent.
Save & Load Project
Designs are stored privately in this browser — nothing is uploaded.
Engineering Formula
- Yf = E_AC / P_DC (final/specific yield, kWh/kWp)
- Yr = H_POA / 1 kW/m² (reference yield, h)
- PR = Yf / Yr
- PR_temp-corrected (IEC 61724-1) = PR / [1 + γ(Tcell − 25)] (γ signed)
PR compares the plant's actual specific yield with the yield it would deliver at STC efficiency under the measured irradiation. It isolates losses (soiling, thermal, wiring, inverter, downtime) from weather variation, so PR is comparable across sites and seasons. Temperature correction removes the thermal component so that only controllable losses remain.
Step-by-step Calculation
- 1.Final (specific) yield Yf
E_AC/P_DC125 kWh/kWp - 2.Reference yield Yr
H/1kW/m²150 h - 3.Performance ratio
Yf/Yr83.33 % - 4.Temperature correction factor
1+γ(Tcell−25)0.93 - 5.Temperature-corrected PR (IEC 61724-1)
PR/[1+γ(Tcell−25)]89.61 %
How to use this calculator: Performance Ratio (PR)
Measured plant PR and specific yield per IEC 61724-1. The example below is calculated by this page's real engine from the displayed inputs.
- 1Confirm that the Performance Ratio (PR) matches the quantity or design check you need.
- 2Enter Installed DC capacity, Plane-of-array irradiation, and Measured AC energy using the units printed beside each field.
- 3Select the applicable Irradiation measurement type and Irradiance sensor type options; these choices change the calculation method or factors.
- 4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
- 5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.
Input guide and example values
Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.
| Input | Example value | Why it matters |
|---|---|---|
| Installed DC capacity | 10 kWp | Measured or known installed dc capacity used by the calculation engine. |
| Plane-of-array irradiation | 150 kWh/m² | Measured or known plane-of-array irradiation used by the calculation engine. |
| Irradiation measurement type | POA (plane-of-array) — correct basis | Select the option that matches the real installation or scenario. |
| Measured AC energy | 1250 kWh | Measured or known measured ac energy used by the calculation engine. |
| Average cell temperature | 45 °C | Signed — can be below 0 °C in cold climates. |
| Power temperature coefficient γ | -0.35 %/°C | Signed, typically negative — never enter as a positive number. |
| Measurement period | 30 days | Measured or known measurement period used by the calculation engine. |
| Irradiance sensor type | Calibrated pyranometer | Select the option that matches the real installation or scenario. |
Formula inputs & variables for Performance Ratio (PR)
These are the named quantities used by this calculator. When the source formula does not define a mathematical symbol, OneCalcApp keeps the real input label instead of inventing one.
| Variable / input | Unit | Meaning in this calculation |
|---|---|---|
| Installed DC capacity | kWp | Measured or known installed dc capacity used by the calculation engine. |
| Plane-of-array irradiation | kWh/m² | Measured or known plane-of-array irradiation used by the calculation engine. |
| Irradiation measurement type | — | Select the option that matches the real installation or scenario. |
| Measured AC energy | kWh | Measured or known measured ac energy used by the calculation engine. |
| Average cell temperature | °C | Signed — can be below 0 °C in cold climates. |
| Power temperature coefficient γ | %/°C | Signed, typically negative — never enter as a positive number. |
| Measurement period | days | Measured or known measurement period used by the calculation engine. |
| Irradiance sensor type | — | Select the option that matches the real installation or scenario. |
How the Performance Ratio (PR) works
The Performance Ratio (PR) uses Installed DC capacity, Plane-of-array irradiation, Irradiation measurement type, Measured AC energy, Average cell temperature, Power temperature coefficient γ, Measurement period, and Irradiance sensor type to calculate Performance ratio, Temperature-corrected PR, Final (specific) yield Yf, Reference yield Yr, and Irradiation basis. Its engine applies Yf = E_AC / P_DC (final/specific yield, kWh/kWp); the worked values below come from that same live calculation rather than a separately typed example.
With Installed DC capacity 10 kWp, Plane-of-array irradiation 150 kWh/m², Irradiation measurement type POA (plane-of-array) — correct basis, Measured AC energy 1250 kWh, Average cell temperature 45 °C, Power temperature coefficient γ -0.35 %/°C, Measurement period 30 days, and Irradiance sensor type Calibrated pyranometer, the main worked-example result is Performance ratio = 83.3 %.
How each Performance Ratio (PR) input is used
Installed DC capacity
The Performance Ratio (PR) worked example uses Installed DC capacity = 10 kWp. This value is passed directly into the calculation, with an allowed minimum 0.1.
Plane-of-array irradiation
The Performance Ratio (PR) worked example uses Plane-of-array irradiation = 150 kWh/m². This value is passed directly into the calculation, with an allowed minimum 0.1.
Irradiation measurement type
The Performance Ratio (PR) worked example selects “POA (plane-of-array) — correct basis”. Available choices include POA (plane-of-array) — correct basis and GHI (global horizontal) — limitation applies. This selection may change the method or factor used by the engine, so choose the option that matches the real case.
Measured AC energy
The Performance Ratio (PR) worked example uses Measured AC energy = 1250 kWh. This value is passed directly into the calculation, with an allowed minimum 0.1.
Average cell temperature
The Performance Ratio (PR) worked example uses Average cell temperature = 45 °C. This value is passed directly into the calculation, with an allowed minimum -20 and maximum 90. Signed — can be below 0 °C in cold climates.
Power temperature coefficient γ
The Performance Ratio (PR) worked example uses Power temperature coefficient γ = -0.35 %/°C. This value is passed directly into the calculation, with an allowed minimum -0.6 and maximum 0. Signed, typically negative — never enter as a positive number.
Measurement period
The Performance Ratio (PR) worked example uses Measurement period = 30 days. This value is passed directly into the calculation, with an allowed minimum 1 and maximum 366.
Irradiance sensor type
The Performance Ratio (PR) worked example selects “Calibrated pyranometer”. Available choices include Calibrated pyranometer, Reference cell, and Satellite-derived. This selection may change the method or factor used by the engine, so choose the option that matches the real case.
Performance Ratio (PR) formulas and result interpretation
Formula 1: relationship used
In the Performance Ratio (PR), Yf = E_AC / P_DC (final/specific yield, kWh/kWp). The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.
Formula 2: relationship used
In the Performance Ratio (PR), Yr = H_POA / 1 kW/m² (reference yield, h). The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.
Formula 3: relationship used
In the Performance Ratio (PR), PR = Yf / Yr. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.
Formula 4: relationship used
In the Performance Ratio (PR), PR_temp-corrected (IEC 61724-1) = PR / [1 + γ(Tcell − 25)] (γ signed). The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.
Performance ratio
For the displayed Performance Ratio (PR) worked example, Performance ratio is 83.3 %. Excellent Verify Installed DC capacity, Plane-of-array irradiation, and Irradiation measurement type and their units before relying on this output.
Temperature-corrected PR
For the displayed Performance Ratio (PR) worked example, Temperature-corrected PR is 89.6 %. Verify Installed DC capacity, Plane-of-array irradiation, and Irradiation measurement type and their units before relying on this output.
Final (specific) yield Yf
For the displayed Performance Ratio (PR) worked example, Final (specific) yield Yf is 125 kWh/kWp. Verify Installed DC capacity, Plane-of-array irradiation, and Irradiation measurement type and their units before relying on this output.
Reference yield Yr
For the displayed Performance Ratio (PR) worked example, Reference yield Yr is 150 h. Verify Installed DC capacity, Plane-of-array irradiation, and Irradiation measurement type and their units before relying on this output.
Irradiation basis
For the displayed Performance Ratio (PR) worked example, Irradiation basis is POA — correct basis. Verify Installed DC capacity, Plane-of-array irradiation, and Irradiation measurement type and their units before relying on this output.
Performance Ratio (PR) accuracy, checks and limitations
- Performance Ratio (PR) units check: confirm Installed DC capacity (kWp), Plane-of-array irradiation (kWh/m²), Irradiation measurement type, Measured AC energy (kWh), Average cell temperature (°C), Power temperature coefficient γ (%/°C), Measurement period (days), and Irradiance sensor type before calculating.
- Performance Ratio (PR) result check: compare Performance ratio, Temperature-corrected PR, Final (specific) yield Yf, Reference yield Yr, and Irradiation basis with the substituted formula steps and the displayed rounding precision.
- Performance Ratio (PR): Use this result for preliminary design and cross-checking. Confirm the applicable code edition, manufacturer data, site conditions and qualified-engineer approval before final design or installation.
Understanding the result
Read the main result together with supporting checks, assumptions, limits and intermediate values.
For a manual check, repeat the first equation, confirm the units and change one input at a time.
Common mistakes when using Performance Ratio (PR)
- Do not mix units for Installed DC capacity (kWp), Plane-of-array irradiation (kWh/m²), Measured AC energy (kWh). A unit mismatch changes the input magnitude even when the typed number looks reasonable.
- Do not leave Irradiation measurement type on the default choice unless that choice matches the real scenario; the selected option can change the calculation path or factor.
- Do not replace the displayed Yf = E_AC / P_DC (final/specific yield, kWh/kWp) relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
- Do not treat Performance ratio = 83.3 % from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.
When the Performance Ratio (PR) is useful
Performance Ratio (PR) is designed for cases where Installed DC capacity, Plane-of-array irradiation, Irradiation measurement type, Measured AC energy are known and you need Performance ratio, Temperature-corrected PR, Final (specific) yield Yf. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.
Use the calculator for the scope described by its inputs and notes. The displayed method is Yf = E_AC / P_DC (final/specific yield, kWh/kWp). If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.
Installed DC capacity and Plane-of-array irradiation: what changes the answer
The worked example uses Installed DC capacity = 10 kWp, Plane-of-array irradiation = 150 kWh/m², Irradiation measurement type = POA (plane-of-array) — correct basis, Measured AC energy = 1250 kWh. With those values, Performance ratio is 83.3 %. Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.
For this calculator, the main input roles are: Installed DC capacity (kWp): Measured or known installed dc capacity used by the calculation engine. Plane-of-array irradiation (kWh/m²): Measured or known plane-of-array irradiation used by the calculation engine. Irradiation measurement type: Select the option that matches the real installation or scenario. Available choices include POA (plane-of-array) — correct basis, GHI (global horizontal) — limitation applies. Measured AC energy (kWh): Measured or known measured ac energy used by the calculation engine.
How to sanity-check a Performance Ratio (PR) result
Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Performance ratio, because it is the first worked-example output shown by the live engine.
Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.
Next logical calculator
Continue with Solar Generation Calculator
Solar Generation Calculator covers the same practical workflow from a related calculation angle, making it a useful cross-check after Performance Ratio (PR).
Open Solar Generation CalculatorStandards, source trail and limitations
References show the method used. Check the current local edition, amendments and project specification before a regulated decision.
Design Assumptions
- • Irradiation measured in the plane of array with a calibrated pyranometer or reference cell.
- • Energy meter at the AC point of delivery over the same interval.
- • No curtailment or grid outages during the measurement window.
Engineering Tips
- ◆Healthy rooftop plants run PR 0.75–0.82; well-kept ground-mount reaches 0.80–0.85.
- ◆Track PR monthly — a steady decline usually means soiling or string failure.
- ◆Temperature-corrected PR is the fair metric for comparing summer against winter.
Warnings
- ▲PR above 0.90 usually indicates a sensor calibration or metering error.
- ▲A short measurement window (< 1 week) gives statistically unreliable PR.
Standards & References
IEC 61724-1 (PV system performance)IEC 61724-2 (capacity evaluation)IS 14286
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