Example Contract Exhibit

PROCEDURE – CAPACITY TEST

I. General#

a. Introduction#

The Capacity Test shall be used to determine that the Facility is performing as designed and shall be performed as a condition to Substantial Completion of the Facility and as otherwise required pursuant to the Agreement.

b. Reference Standards#

The reference standards for the Capacity Test include:

1. ASTM E2848-13 (2018), “Standard Test Method for Reporting Photovoltaic Non-Concentrator System Performance” as modified to use module temperature in place of ambient temperature and wind velocity readings.
2. ASTM E2939-13 (2018) “Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator Systems” as modified to use module temperature in place of ambient temperature and wind velocity readings.
3. IEC 61724-2 (2016) “Photovoltaic system performance-Part 2: Capacity evaluation method”
4. IEC 61724-1 (2021) “Photovoltaic system monitoring”
5. ISO/IEC 17025 (2017), “General requirements for the competence of testing and calibration laboratories.”

These standards and their reference documents shall be used to perform the Capacity Test, as defined in Section IV. Allowed modifications from these standards are listed in Section II.

c. Final Results#

The Final Results of the Capacity Test procedure shall be reported in an unambiguous format per the selected Test Method, Test Boundary, Allowances, Reference Conditions, and Acceptance Criteria. Additionally, constrained test results shall be utilized if indicated in Section IV, as conditions allow.

II. Test Guidelines#

a. Definitions#

The following terms are herein defined for this Capacity Test. The purpose of defining these key terms is to remove the ambiguity of terminology between the various reference standards.

1. Constrained Operation. Operation of the Facility when the power injected into the grid is limited by the output of all the inverters either due to their per their AC rating (i.e. inverter clipping), Facility rating (i.e. POI clipping), or other grid requirements (i.e. curtailment, power factor response, etc.).
2. Unconstrained Operation. Operation of the Facility when all inverters are freely following the DC power response to irradiance and output is otherwise not limited.
3. Test Model. The simulation model of record or proxy model used to calculate the predicted or expected PV power generation based on the Test Model Parameters
4. Expected Power. Power generation of the Facility that is expected for actual weather data collected at the site based on the Test Model Parameters of the system.
5. Predicted Power. Power generation of the Facility that is calculated with a specific performance model, using historical weather data that is considered to be representative for the site.
6. Measured Power. Power that is measured by the Facility meter and injected into the grid or storage elements.
7. Test Ratio. The ratio of Measured Power to Expected Power, whether by regression fit comparison (ASTM E2848) or corrected power comparison at target reference conditions (IEC 61724-2).
8. Reporting Conditions (ASTM E2848/E2939), or Target Reference Conditions (IEC 61724-2). The allowed range of conditions that may be included in this test, as defined in Table 3.
9. Allowable Records. Valid test records per the reference standards, including ranges and filters as defined in Table 4.
10. Test Uncertainty. Expanded Test Uncertainty (K=2) As defined in the reference standard using the Guide to the expression of uncertainty of measurement (GUM).
11. Test Model Parameters. Electrical design parameters that influence Expected Power, including but not limited to: DCstc capacity, AC system max output, DC static losses, DC and AC ohmic losses, module temperature coefficient, and inverter CEC efficiency rating.

b. Test Model#

1. The Test Model shall be agreed upon in advance of the Capacity Test and used as the basis for calculating Expected or Predicted Power. The Test Model shall include a report of all Test Model Parameters and, if required by Section IV, a .csv hourly output file.
2. If required in Section IV, the Predicted 8760 .csv file shall contain the following parameters:

Parameter	PVsyst Field	Units	Purpose
Date and Time	Date and Time	MM/DD/YYYY hh:mm	Final Results
Global Horizontal Irradiance	GlobHor	W/m²	Optional Analysis
Global Incident Irradiance	GlobInc	W/m²	Final Results (flat spectrum pyranometer)
Shade Ratio	FShdGl		Final Results (filter)
Direct Shade	ShdBLss	W/m²	Final Results (filter)
Diffuse Shade	ShdDLss	W/m²	Final Results (filter)
Albedo Shade	ShdALss	W/m²	Final Results (filter)
Electrical Shade	ShdElec	W/m²	Final Results (filter)
Effective Irradiance (POA)	GlobEff	W/m²	Final Results (similar spectrum pyranometer or reference cell)
Effective Irradiance (reverse POA)	GlobBak	W/m²	Final Results (for bifacial modules)
Cell Temperature	TArray	°C	Final Results
Ambient Temperature	TAmb	°C	Optional Analysis
Wind Speed	WindVel	m/s	Optional Analysis
Power Injected into the Grid	E_Grid	kWh	Final Results

c. Proxy Model#

1. If the Test Model is not API-based, a proxy model shall be generated and used if required in Section IV. The Proxy Model shall utilize the Test Model Parameters using a Single Diode model and best practices as documented by the Photovoltaic Performance Modelling Collaborative (PVPMC). The Predicted Energy difference between the simulated model of record and the proxy model shall be documented in the Capacity Test report.

d. Data Collection#

1. Benchmarking and reporting for this test shall follow the requirements of IEC 61724-1 (2021). Measurement devices shall be consistent with the Test Boundary selection, including:

   1. Plane of Array (POA) and Rear Plane of Array (rPOA) irradiance measurements may include spectrally flat thermopile pyranometers, similar spectrum fast response photodiode pyranometers, or matched reference cells as required by the Test Boundary selection. If similar or matched spectrum sensors are used, the Test Report must clearly indicate whether Global Incident or Effective Irradiance is used in the Capacity Test analysis. Pyranometers shall have a Calibration Uncertainty (K=2) < 2% and be calibrated within 1 year by an ISO/IEC 17025 Accredited Calibration Laboratory.

   2. Cell Temperature (Tcell) calculation shall be derived from Back of Module temperature (Tbom) measurements and applying the NREL Open Back conversion to Calculated Cell Temperature based on the Irradiance:

      Tcell = Tbom x (1+.003* POA Irradiance)

      Back of Module temperature sensors shall have validated temperature readings consistent with manufacturer specifications.

   3. Power generation shall be measured using an ANSI C12.20 Class .2 or higher meter. Meter accuracy shall be documented in a certified statement of conformity by the manufacturer. Meter measurement shall be validated against inverter power measurements prior to the start of the Capacity Test to identify potential human error during set-up.

e. Reference Standards and Allowed Modifications#

The Test Ratio shall be computed per methods defined in their respective standards. Where variations in methodology exist between standards, and to reduce Test Uncertainty, specific modifications are allowed, including:

1. Use of module cell temperature to replace derived calculations from ambient temperature and wind speed, as suggested by IEC 61724-2 (2016) Clause 5 to provide better reproducibility and lower test uncertainty. This modification shall replace ASTM E2848 (2018) Equation (1) with the following:

   P=E*(a1+E*a2+T*a3)

   where,

   • P is the Test Model Predicted Power
   • E is irradiance as defined by the Test Boundary
   • T is cell temperature
   • a1, a2, and a3 are regression coefficients described by ASTM E2848 (2018)

f. Test Period and Special Conditions#

1. The Test Period shall include a minimum of 3 days and maximum 30 days, unless the Parties agree to an extension.
2. For tracking systems that cannot produce adequate unconstrained Allowable Records due to system clipping, the tracker may be stowed in the horizontal position until the minimum allowed unconstrained records and test uncertainty are attained.

III. Test Report#

The Test Report shall include all required information as outlined in the reference standards per the selected Test Methodology of Section IV, including the associated data file in .csv format:

1. ASTM E2848E Section 10
2. IEC 61724-2 Section 7
3. ISO/IEC 17025 Section 7

IV. Test Options and Parameters#

a. Test Methodology#

(choose the test standard to report the Final Results)

[__] ASTM E2848-13 (2018) Regression test using Expected Target Capacity derived from the hourly predicted Test Model data

-or-

[__] IEC 61724-2 (2016) Non-regression test of unconstrained power using an API-based or Proxy Test Model (Constrained results shall be provided, if available)

b. Test Boundary#

(choose the scope of the test)

[__] PV System and Site Conditions (Spectral, reflection, and shade losses are inside the test boundary)

• Utilize Flat Spectrum Pyranometers (ISO 9060 Class A) to measure broad spectrum irradiance (front) and similar spectrum Fast Response Pyranometers [Deno sensors] to measure effective irradiance (back)
• Utilize Back of Module Temperature Sensor measurements
• Treat POA as full-spectrum incident irradiance in Test Model

-or-

[__] PV System Only (Spectral, reflection, and shade losses are outside the test boundary)

• Utilize similar spectrum Fast Response Pyranometers [Deno sensors] to measure effective irradiance (front and back)
• Utilize Back of Module Temperature Sensor measurements
• Treat POA as effective irradiance in Test Model (front and back)

c. Allowances#

The Final Results of the Capacity Test shall include the following Allowances:

Table 1. Allowances for Unconstrained Operation.

Allowance	Value	Explanation
Soiling	[ 0.5% ], or As Measured and agreed by parties to this Agreement	An assumed soiling level during the capacity test that is not included in the Test Model. Irradiance measurement sensors shall be clean during the Test Period.

d. Reporting Conditions and Data Filters#

The Final Results of the Capacity Test shall be derived from the following Reporting Conditions and Filters for Unconstrained Operation:

Table 2. Reporting Conditions and Filters for Unconstrained Operation.

Reporting Conditions

• Excluded Points: Outage, Snow, Shade
• Minimum POA Irradiance is 400 W/m² (350 W/m² may be used if testing cannot be completed within 2 weeks due solely to irradiance)
• Maximum POA Irradiance is 1000(DC:AC) W/m²
• Irradiance RC is 60th percentile of remaining data
• Temperature RC is the average of remaining data

Allowed Points Filters

Measurement	Stability Validation	Minimum Filter	Maximum Filter
POA/Effective Irradiance (W/m²)	Standard deviation < 10 % of the average of raw interval	0.8 of RC (minimum 300 W/m²)	1.2 of RC
Cell Temperature (°C)	N/A	-10 °C	70 °C
Measured Power (kW)	N/A	0 x AC Max Output	0.95x AC Max Output

Note: For Constrained tests, Expected Power values are defined by the Test Model maximum power output.

e. Acceptance Criteria#

The Final Results of the Capacity Test shall be derived from the following minimum criteria and other Test Parameters defined herein:

Table 3. Acceptance Criteria

Mode	Minimum Test Ratio	Minimum Allowed Records	Record Interval	Maximum Test Uncertainty (K=2)
Unconstrained	[.98]	[50/150]	15/5 Minutes	[5%]