NBSIR 80-2060

Drafting Test Methods for

Photovoltaic Systems

W. F. Lankford and H. A. Schafft

Electron Devices Division

Center for Electronics and

Electrical Engineering

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

June 1980

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NBSIR 80-2060

DRAFTING TEST METHODS FOR

PHOTOVOLTAIC SYSTEMS

W. F. Lankford and H. A. Schafft

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Electron Devices Division

Center for Electronics and

Electrical Engineering

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

June 1980

Prepared for Solar Energy Research Institute

Golden, CO 80401

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity. Technology, and Innovation

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

Table of Contents

Page

Abstract 1

1. Introduction 1

2. Introduction of a Test Method Draft to a Standards-Writing

Committee — General Considerations . 4

3. Effectiveness Criteria for Test Method Standards • 5 3.1 Practicality and Economic Feasibility ....... 5 3.2 Lack of Impedance of New Development 5 3.3 Avoidance of Unfair Discrimination ... ... 5

4. Preparatory Work for Writing and Introducing a Test Method .... 6

4.1 Background Information Search . 6

4.2 Appropriateness of Method ...... 6

4.3 Principles and Assumptions 8

4.4 Experimental Error Analysis 8

4.5 Areas of Dispute 8

4.6 General Criteria ..... 9

4.7 Basic References .... 9

4.8 Intralaboratory Study 9

4.9 Inter laboratory Pilot Study 9

5. Procedure for the Preparation of A Preliminary Test Method Draft . 10

5.1 Title 10

5.2 Scope 10

5.3 Use 10

5.4 Significance 10

5.5 Summary of Method 11 5.6 Definition, Terminology, and Symbols 11 5.7 Apparatus and Materials 11 5.8 Safety 11 5.9 Statistical Sampling and Measurement 11 5.10 Procedure 12

5.10.1 Error .. ....... 12

5.10.2 Checks ..... .. 12

5.10.3 Illustrations .. 12

5.10.4 Experience 12

5.10.5 Statistical Requirements . ... 12

5.10.6 Repeated Measurements 12

5.10.7 Interferences 12

5.10.8 Alternatives 13

5.10.9 SI Units 13

5.11 Calculations and Reporting 13

5.12 List of References 13

5.13 Table of Contents 13

Acknowledgment 14

References 14

_iii
N

'
Drafting Test Methods for Photovoltaic Systems*

* William F. Lankford

and

Harry A. Schafft

Electron Devices Division

Center for Electronics and Electrical Engineering

National Bureau of Standards

Washington, DC 20234

Abstract

General guidance and a step-by-step procedure are provided as aids

in the development of initial drafts of test methods for photovoltaic energy components and systems. It is intended that these

drafts will be referred to the appropriate technical committees of

organizations writing voluntary consensus standards. This approach

is designed to facilitate the expeditious development of consensus test method standards for photovoltaic systems. The procedure is

therefore designed to be compatible with the requirements of existing standards organizations.

Key Words: Consensus standards; measurement technology; photovoltaic energy conversion; photovoltaics ; solar cells; test method

preparation.

1 . INTRODUCTION

The availability of photovoltaic (PV) energy conversion as a competitive

source of power has been brought closer by improvements in terrestrial solar

cell technology, significant reductions in the costs of PV systems and components, and an increasing awareness of the limitations and total costs of en- ergy sources now being used.

A critical element in promoting an early and practical commercialization

of PV energy conversion systems is a base of well-documented and widely ac- cepted standards that are responsive to marketplace requirements . It is

preferable that such a base of voluntary standards be developed by the con- sensus process to ensure acceptability. When the base is in place, it should

facilitate reliable and consistent measurements. A recent review [1] has re- vealed, however, that there are few standards in place that are directly applicable to PV energy conversion systems and that, in fact, much work needs

to be done to develop the standards base required for the full and effective

use of PV systems on the scale that will make the PV option a viable one for

the nation.

In the United States, the responsibility for developing standards for

materials and products is assumed by consensus standards-writing organiza-

*This report was prepared under contract to the Solar Energy Research

Institute (Subcontract No. XP-9-8028-1) in support of the Photovoltaic

Performance Criteria and Test Standards Project.

1
tions within professional societies, standards organizations, and trade asso- ciations. Such organizations typically form various technical committees

where the actual work of developing standards is carried out. The committees

may include interested industry, user, government, and consumer representatives who prepare, revise, and approve the drafts of standards. The products

of the technical committees are then subject to review through the ballot

process and, when approved by the parent organization, may be submitted to

the American National Standards Institute for adoption as American National

Standards. Institutions such as the Institute of Electrical and Electronics

Engineers (IEEE), the American Society for Testing and Materials (ASTM), and

the Semiconductor Equipment and Materials Institute, Incorporated (SEMI) are representative of those concerned with standards for photovoltaic solar ener- gy systems

.

The development of a voluntary consensus standard is achieved most ra- pidly when there already exist one or more we11-doclamented test methods com- monly used in the field and the problem is to codify at least one of these

methods and determine its precision in actual practice. It is often the case that little or no experimental development is required to achieve standardization of those methods. However, when significant research and evaluation

work is necessary before an adequate initial draft of a test method can be

prepared, the process of standards development by standards-writing organizations can be lengthened considerably. The Solar Energy Research Institute

(SERI), as part of its response to the Photovoltaic Research, Development,

and Demonstration Act of 1978 (PL-95-590), is managing a project to develop

performance criteria and test methods for photovoltaic materials, components,

subsystems, and systems. Promoting the expeditious development of test method standards is an important part of the project. SERI recognizes that significant preparatory work may indeed be needed to provide a foundation for

important PV test methods and that this situation can cause significant delays in the development of the needed standards base. SERI, therefore, is

interested in supporting, where appropriate, both the research and evaluation

needed for the development of test methods, and the detailed preparation of

initial drafts of such test methods in a form suitable for introduction to

appropriate standards-writing organizations at a point where the consensus process can most effectively take over.

This report is directed to those involved in the development of these

test methods and the preparation of initial test method drafts. These two

activities, for a given test method, are regarded here as one unified effort.

Sections 2 and 3 provide general considerations designed to facilitate con- sistency in the generation of the initial drafts. Section 4 provides a framework for the accelerated development of test methods and, in particular,

for the orderly introduction and transfer of the test method drafts to the

technical committees of standards-writing organizations. Finally, Section 5 gives the step-by-step procedure for preparing a test method. This procedure

necessarily cannot be too specific, as it is intended to reflect the requirements of most of those organizations that appear likely to be the most involved in PV standards development [2-6] . The specific provisions, level of

detail, and even the general approach varies considerably from one organization to another. The procedure has been carefully designed to conform with

the instructions of the individual standards-writing organizations.

2
Table 1 outlines the steps described in this report for preparing a test

method draft and developing it into a standard. These steps are ones that

the preparer of a test method will need to consider and follow, as appropriate and as SERI may direct.

It should be pointed out that while the focus of the report is on the

expeditious development of standards for PV systems, the guidelines and rec- ommendations given here serve equally for other technologies in a similar

stage of development.

Table 1 — steps for Preparer of Test Method Draft (with Sections Where These

Steps are Discussed)

3
2. INTRODUCTION OF A TEST METHOD DRAFT

TO A STANDARDS-WRITING COMMITTEE - GENERAL CONSIDERATIONS

The effectiveness of standards developed for PV systems depends on their

acceptance and employment in the marketplace. These in turn depend on how

well they satisfy perceived needs and to what degree all interested parties

feel they have had a chance to participate in their development. Although

the use of a standard is voluntary in principle, standards developed by the

voluntary consensus process are frequently cited by federal, state, and local

governments and they may find use in legally binding codes and regulations.

This eventuality makes it essential to document carefully the development of

the standard including the preparation of the initial drafts which will serve

as the base on which the completed standard is built.

The background work in developing the initial draft of a test method

should be designed to facilitate its eventual development into a standard

test method by a consensus standards-writing organization. A clear distinction must be drawn between the development of the initial draft of a test

method and the process by which the final standard is adopted by the

standards-writing organization. The former involves the careful translation

of a measurement technique into a precisely written description of a test

method and may involve significant experimental work at the laboratory level.

The latter involves the consensus process whereby all interested parties participate in the development of a standard test method. Thus, the work on the

initial draft should be considered as staff support work for the technical

committee to which the draft will be submitted.

It is important that adequate coordination be developed between the or- ganization preparing the initial draft and the technical committee. This

should be initiated as soon as possible by the preparing organization for two

reasons: (1) to insure an effective response by the technical committee as a result of their early involvement and (2) to avoid unfair discrimination

against any product or technology by allowing the opportunity for timely inputs from interested parties (as discussed in sec. 3.3). The coordination

with the technical committee may take different forms: for example, it may

only involve an initial introduction of the project and the submission of

subsequent progress reports to the committee, or it may involve having a representative become an active participant on the committee from the outset.

The latter approach will generally be far superior to the former. In any

event, after the draft is introduced, a representative should attend meetings

of the committee to assist in the process of developing the draft into a consensus standards document.

The selection of appropriate standards-writing organizations for proposed test method drafts and the identification of the target technical com- mittees of those organizations are expected to be made by mutual agreement of

the standards-writing organizations represented at meetings of the Subcommittee on Photovoltaics of the ANSI Steering Committee on Solar Energy Standards

Development.

4
3. EFFECTIVENESS CRITERIA FOR TEST METHOD STANDARDS

The organization preparing the initial test method draft should evaluate

the draft against the following three general criteria for effective voluntary consensus standards. This should be done both as the draft is being

planned and later after it is completed, prior to its introduction to the

standards committee. The draft must pass these tests if the standard is to

be expected to meet with acceptance by the FV community.

3.1

Practicality and Economic Feasibility

The first criterion is that the test method be practical and economically feasible to use. This requires that due consideration be given to the

cost of the necessary equipment and facilities, to the time to conduct the

test, and to the demands on the skills of the operator performing the test.

A related requirement is that the levels of precision and accuracy of the

test method be matched to the needs of the PV community. To exceed these

needs will needlessly raise the cost and complexity of the test; to fall

short of them will make the test method unacceptable as a means of deciding

marketplace questions.

3.2

Lack of Impedance to New Development

The second criterion is that the test method in no way impede technological development and marketing of new and innovative PV devices and systems.

This objective can be achieved in large part by using performance criteria

instead of relying on prescriptive specifications. For example, in specifying the apparatus required for a test, if its capability of making a given

measurement is the concern, the capability in question should be specified

without restrictions as to how the measurement is to be accomplished, unless

the way in which the measurement is made impacts the overall results to a significant degree. The specification of capability should thus include the

necessary range, precision, accuracy, etc. As a specific example, the use of

a temperature sensor with a specified accuracy or sensitivity over a specified temperature range should be required rather than the use of a given type

of thermocouple.

3.3

Avoidance of Unfair Discrimination

The third criterion is that the test method avoid unfair discrimination

against one product or technology in favor of another. This can be achieved

for the most part by carefully defining the applicability of the test method

and through the development of parallel options in the methods.

The problem of unfair discrimination of a test method against a particular product because of technical difficulties in applying the test largely

can be avoided by involving as many interested manufacturers as possible in

the test method review process. This procedure is, in fact, one of the principal functions of the standards-writing committee. The importance of avoiding this unfair discrimination is sufficiently important that it should be

considered in the first stages of test method development.

5
4. PREPARATORY WORK FOR WRITING AND INTRODUCING A TEST METHOD

As a useful framework for the preparation of a test method draft, and as

a way of testing and demonstrating the validity of the method itself, a num- ber of steps are proposed to the preparer of a draft and are described in

subsections 4.1 through 4.9. Following these steps will help ensure that the

test method and the draft rest on firm technical grounds and that the method

is practical and useful. It will also provide the supporting information

that should be used when the draft is introduced to the technical committee

of the standards-writing organization. This information should be documented

in a companion report to the draft which is to be prepared and submitted with

the draft to the technical committee, after review by SERI. The report will

serve, additionally, as a useful reference document for the technical committee as it proceeds in the consensus process to develop the initial draft into

a standard.

All of the steps listed below need not be followed to develop a satisfactory initial draft. Some may not even be appropriate to a given test

method. Nevertheless, it is emphasized that these steps are designed to

facilitate and accelerate the development of the initial test method draft to

a consensus standard. This is accomplished by providing the substantiation*

of the test method that can be used to answer the questions that would be ex- pected to be asked by the technical committee and others involved in the con- sensus process.

4. 1 Background Information Search

Collect sufficient background material on the measurement method to en- sure that any information relevant to its development into a test method

draft is at hand. This may be accomplished with the aid of personal contacts

with authorities in the field and by a search of the literature. The search

should seek all reports of background research directly applicable to the

method, as well as all reported experience in using the method. The scope of

the search should include both government reports and the open technical literature. A list of some available data bases that should be considered is

provided in table 2.

4.2 Appropriateness of Method

Prepare a background statement about the proposed test method describing

its appropriateness for making the required measurement. Describe any com- peting measurement methods and justify why those methods are less appropriate

for the desired measurement. Reference should be made to any closely related

test methods that have already been adopted as standards. Reference [7] may

be helpful in the search for such methods. As new test methods are developed

for photovoltaics, the ANSI Steering Committee on Solar Energy Standards Development should be consulted for an up-to-date list of test methods. If

such closely related standards do exist, the difference between the published

standard and the proposed test method should be discussed with emphasis on scope and applicability. The conditions under which the proposed method may

Some technical committees may refer to this substantiation as the

"rationale" for the candidate standard.

6
Table 2 — Data Bases and Availability for Computer Searches of PV Test Methods

Code

NTIS National Technical Information Service’*' includes access to almost all U.S.

Government reports (availability B,L,S).

RECON Department of Energy code which includes some reports not accessed through the

NTIS search (availability: E).

COMPENDEX Access to the worldwide engineering and technological literature (availability:

L,S).

CA/SEARCH Access to the worldwide literature in chemistry and chemical engineering (availability: B,L,S).

SEIDB Solar Energy Information Data Bank provides comprehensive access to the litera- ture including patents (availability: SERI).

STAR Scientific and Technical Aeroscope Reports: NASA sponsored reports (availability : NASA )

.

INSPEC Worldwide coverage of the literature in physics, electrotechnology, computer and

control engineering. A British data base (availability: B,L,S).

INSPEC A Physics abstracts.

INSPEC B Electrical and electronic abstracts.

INSPEC C Computer and control abstracts.

Availability :

B Bibliographic Retrieval Services, Inc. Building 702

Corporation Park

Scotia, NY 12302

(518) 374-5011 L Lockheed Information Systems

Code 5020/201

3251 Hanover Street

Palo Alto, CA 94304

(800) 227-1960

E Department of Energy

Director, Office of Technical Information

Washington, DC 20545

(301) 353-4357

S Systems Development Corporation Search Service

2500 Colorado Avenue Santa Monica, CA 90406

(213) 829-9463

N National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

(703) 557-4642

NASA National Aeronautics and Space Administration

Office of Technology Utilization

Scientific and Technical Information Division

600 Independence Avenue, S.W. Washington, DC 20546

(202) 755-2210

SERI Solar Energy Information Center

Computerized Databases

Solar Energy Research Institute

1536 Cole Boulevard

Golden, CO 80401

(303) 231-1960

National Technical Information Service, Springfield, VA 22161, Tel: (703) 557-4780.

Access to these sources is also provided by many large public libraries and universities.

7
be used instead of the published one should also be discussed. If the proposed test method complements an existing standard, the conditions for which

each applies and the benefit to be gained from the proposed method should be

identified.

4.3

Principles and Assumptions

Specify any fundamental scientific or engineering principles on which

the test method is based. State any fundamental assumptions on which the

method is based, and indicate how the validity of these assumptions can be

checked. Also, include any precautions in interpreting the results of the

test which relate to the assumptions made.

4.4

Experimental Error Analysis

Make an analysis of how various aspects of the measurement method may

introduce errors in the value of the quantity to be determined by the method?

aspects such as measurement procedure, condition and type of test specimen,

apparatus, and laboratory conditions should be considered. It is useful in

the formative stages of a measurement method to predict the anticipated precision and accuracy of the method, based on elementary laboratory error analysis. Such an analysis may be able to suggest timely modifications in the

procedure or other aspects of the method that will contribute to an improved

measurement.

The analysis should include an estimate, either from actual trials or by

a theoretical investigation, of the magnitude of error that might reasonably

be expected in the measurement of each parameter. It should also determine

how measurement results may be affected by variations in critical instrumentation, specimen type and preparation, ambient conditions, and operator performance. The effect of all these possible sources for measurement error on the quantity to be determined by the test method should be calculated by ac- cepted propagation of error techniques [8].

If the magnitude of the calculated error warrants, an investigation

should be conducted to find alternative procedures or approaches which will

make the method less sensitive to measurement variables. If other options

become evident, use error analyses to aid in the selection of the optimum

procedure

The results of error analyses and the conclusions derived therefrom

should be included in the companion report to the preliminary draft test

method.

4.5

Areas of Dispute

Identity any areas of likely dispute over the specifications or procedures of the test method. Describe the reasons for any dispute, indicating

the pros and cons of any likely alternatives.

8
4. 6 General Criteria

Demonstrate that the draft test method meets the general criteria in

section 3 by addressing the following issues where appropriate:

a. COST of the test,

b. TIME required to perform the test,

c. SKILL level required,

d. APPROPRIATENESS of precision and accuracy levels,

e. FLEXIBILITY of the test method to new technology, and

f. BREADTH of applicability to known and anticipated products.

4.7 Basic References

Prepare a list of those documents that form the basic references for the

test method and which should be of value to the reviewing standards committee

and to a potential user of the method. Each entry should be accompanied by a statement explaining why the paper should be of interest. The test method

draft should, however, be self-contained in that the user should not be re- quired to consult the references for a successful application of the test.

References are used to provide additional information such as the origin of a functional relationship expressed in an equation.

4.

8

Intralaboratory Study

Evaluate the instructions for performing the test method for completeness and clarity by observing an operator following these instructions who is

uninitiated in the method yet experienced in the general measurements re- quired. Where problems are apparent in following the instructions, the instructions must be appropriately modified. The adequacy of the instructions

and the method itself may be tested by having several operators perform the

test method on the same or similar test specimens and noting the variation in

test results.

4.9

Interlaboratory Pilot Study

When there exists little experience with the test method or when a high

degree of precision is required, it may be useful to conduct an interlaboratory pilot study after the initial draft has been prepared. Where a technical committee of a standards writing organization has been identified to have

an interest in the initial test method draft being written and a pilot study

is justified, the pilot study should be coordinated by that committee, if

practical. The pilot study should involve only two or three laboratories in

addition to the one developing the test. The interlaboratory pilot study is

intended to be a less formal and less rigorous interlaboratory experiment

than the committee may wish to conduct later as a final evaluation of the

test method. The purposes of a pilot study are usually threefold:

a. To assess the general technical feasibility of the test method.

b. To identify any major technical problems that arise in applying the

test.

c. To obtain a preliminary indication of the precision that might be

expected of the test method and to identify those measurement parameters which are the principal contributors to error in the method.

9
5. PROCEDURE FOR THE PREPARATION OF A PRELIMINARY TEST METHOD DRAFT

The steps listed below should be followed in the preparation of initial

test method drafts intended for introduction to standard s-writing organizations. The procedure is intended to standardize the preparation of such

drafts so that they will have an acceptable level of completeness and uniformity. The completion of each of the steps below will result in a part or

a section of the test method draft according to the headings indicated:

5.1 Title

Select a title that is fully descriptive of the particular test method.

Consult other related published standard test methods to determine that no ambiguity exists. It will be left to the technical committee to develop a title that may be more concise and readily indexable.

5.2 Scope

Specify the scope of the test method. Include a statement of the

purpose of the method and the range of application. Make sure the scope

statement provides the reader with enough information to determine whether or not the test method meets his or her measurement requirements. To avoid

possible misinterpretation, specify explicitly those conditions for which the

method does not apply as well as for those for which it does. For example,

specify clearly the solar cell types for which a cell test method is intended

as well as those for which it is not suitable.

The applicability of the test method to various devices or systems

should be as broad as possible to extend the benefits of standardization to as large a class of items as is feasible. Since the absence of a standard

test method for the performance of a given product can inhibit its commercial

viability, no product should be excluded except for sound technical reasons.

On the other hand, only that range of products for which the method can be

tested by interlaboratory comparison should be included.

5.

3

Use

State the context in which the test method being proposed may be used.

For example, is it appropriate for use in research and development, in quality control by the manufacturer, in specification checking by the consumer,

or in the satisfaction of regulation or code requirements? If there are any

reasons why the proposed test method would not be satisfactory in a given

context, identify these limitations.

5.4

Significance

State the technical importance of the test method and its overall significance to the industry or discipline involved.

10
5.5

Summary of Method

Describe the method briefly, including any names commonly used to refer

to it. Outline enough of the procedure that the reader can determine the

basic method without having to go through the detailed procedure.

5.6

Definition, Terminology, and Symbols

Collect definitions, terminology, and symbols used in the method. In

any field, technical terms and jargon inevitably become part of the working

vocabulary. Make sure that this collection is sufficiently complete (together with terminology from other documents which are referenced as being

essential for carrying out the method) that a technically trained person outside the field can understand all the terms used in the draft test method.

Use standard definitions, terminology, and symbols when available. Ensure

that all definitions are consistent with those already defined in published

standards.

5.7

Apparatus and Materials

Describe the test equipment and expendable supplies required by the test

method. Specify any levels of performance that are needed in the test equipment and supplies for a satisfactory execution of the test. For example, if

a current meter requires at least one-percent accuracy, it must be so specified rather than indicating simply that an accurate meter is needed. The

range of values over which an instrument must have a certain accuracy should

be specified. However, it is important not to require greater accuracy than

is actually needed. In general, one should avoid prescriptive specifications

that would tie the test to a particular piece of apparatus. Having provided

a generic description of the required capabilities, it may be useful, however, to indicate that a given kind of apparatus has proven to be satisfactory for the prescribed use. This guidance may facilitate the selection of

apparatus for the test. If such a statement is made, the policy of the or- ganization for whom the initial draft is intended should be consulted for its

endorsement disclaimer.

5.8

Safety

Describe any safety precautions that must be followed by personnel con- ducting the test.

5.9

Statistical Sampling and Measurement

Recommend any statistical sampling techniques required by the test

[9,10]. If, for example, the test method is used for quality control in a manufacturing process, suggest such important quantities as the percentage of

production units to be selected for testing and the manner of selection. It

is possible that such a sampling plan will depend on data from actual production experience which may not be available at this stage. When such data

become available, it may be necessary to modify the sampling techniques.

11
5.10 Procedure

Write out the detailed step-by-step procedure to be followed in logical

order in the conduct of the test method.

Consider the following points and include material responding to those

that are appropriate:

5.10.1 Error

Identify those parts of the procedure which are particularly likely to

introduce measurement error. (Provide in notes suggestions for avoiding

such errors.

)

5.10.2 Checks

Include any checks that can be made in the course of the measurement

which will help to verify the accuracy or precision of intermediate

steps

.

5.10.3 Illustrations

Provide illustrations (i.e., structural diagrams, etc.) when pictorial

representation will aid understanding. (Caution: use the same labels

in text and figures.)

5.10.4 Experience

As a result of experience with a given test method, it may be discovered

that special care must be exercised in certain steps. Include the benefit of this experience in the written procedure of the method whenever

possible, or incorporate suggestions (i.e., nonessential instructions)

in notes.

5.10.5 Statistical Requirements

Incorporate in the procedure any statistical requirements that are imposed by the test method itself. For example, where a measured parameter is subject to random fluctuations, it may be necessary to call for an average of several measurements to obtain the needed accuracy.

Specify in the procedure how many measurements are to be made and how

the data are to be recorded and tested.

5.10.6 Repeated Measurements

Include in the procedure, as required, instructions for repeated mea- surements on the same specimen over an extended period of time. Specify

an appropriate time interval between tests when such a need exists.

5.10.7 Interferences

Describe in notes (or, optionally, in a separate section) any potential

interferences with the test method that may be anticipated. Interfer12
ences are those factors which may affect the precision or reproducibility of the test in ways that are difficult or impractical to quantify.

An example of an interference is foreground surface reflection in outdoor PV device measurements.

5.10.8 Alternatives

There may be cases where there are several alternative procedures that

involve a balancing of factors, all of which are not attainable in one procedure. Where these alternatives are technically acceptable and the

test is to be used as part of a buyer-seller transaction, it may be desirable to allow this choice to be "subject to agreement by the parties

of the test." If this choice is allowed, describe the trade-offs of the

factors in each alternative so that buyer and seller may mutually be

able to select the best procedure for the situation at hand.

5.10.9 SI Units

Use SI units [11] throughout. One of the major near-term markets ex- pected for PV system is the export market. It is very important therefore that quantities in PV test methods be expressed in the international system of units even though customary engineering units are also indicated.

5.11. Calculations and Reporting

Specify how any calculations are to be made and how the test results

should be reported in a step-by-step procedure. For complex tests provide a standard report form as part of a draft.

5. 12 List of References

Prepare a list of those references referred to in the text of the initial test method draft.

5.13 Table of Contents

Include a table of contents for those drafts where length and complexity

warrant

.
Acknowledgment

The authors would like to acknowledge and thank those who provided helpful comments to earlier drafts which allowed us to make this a more complete

report. Special thanks go to J. Franklin Mayo-Wells for his particularly

knowledgeable and diligent reviews.

References

1. Schafft, H. A., Standards for Photovoltaic Energy Conversion Systems,

NBSIR 79-1743. [Available from the National Technical Information

Service, Springfield, VA 22161, using order number PB 296 274, Tel:

(703) 557-4780]

2. Form and Style for ASTM Standards, Fourth Edition (June 1976). [Available from ASTM, 1916 Race Street, Philadelphia, PA 19103, Tel: (215)

299-5400]

3. IEEE Standards Manual and Style for IEEE Standards (March 1978).

[Available from the IEEE Headquarters, 345 East 47th Street, New York,

NY 10017, Tel: (212) 644-7960]

4. Style Manual for Preparation of American National Standards (August

1972). [Available from the American National Standards Institute, 1430

Broadway, New York, NY 10018, Tel: (212) 354-3300]

5. Method of Development, Revision, and Implementation of Underwriters

Laboratories Standards for Safety (1978). [Available from Underwriters

Laboratories, Inc., 207 East Ohio Street, Chicago, IL 60611, Tel:

(312) 642-6969]

6. Style Manual for EIA Publications (March 1974). [Available from EIA,

2001 Eye Street, N.W., Washington, DC- 20006, Tel: (202) 457-4900]

7. An Index of U.S. Voluntary Engineering Standards, W. J. Slattery, Ed.,

NBS Special Publication 329 (March 1971). [Available from the National

Technical Information Service, U.S. Department of Commerce, Springfield,

VA 22161, using order number COM 71-50172, Tel: (703) 557-4780]

An Index of U.S. Voluntary Engineering Standards, W. J. Slattery, Ed.,

NBS Special Publication 329, Supplement 1 (December 1972). [Available

from the National Technical Information Service, U.S. Department of

Commerce, Springfield, VA 22161, using order number COM 73-50679, Tel:

(703) 557-4780, also available as updated microforms]

An Index of U.S. Voluntary Engineering Standards, W. J. Slattery, Ed.,

NBS Special Publication 329, Supplement 2 (May 1975). [Available from

the Superintendent of Documents, U.S. Government Printing Office,

Washington, DC 20402, using stock number 003-003-01362-5, Tel: (202)

783-3238]

N.B. These indexes are being consolidated into one updated document

which is expected to be available by fall 1980.

14
8. Beers, Y., Introduction to the Theory of Error ( Addis on-Wes ley Publishing Co., Reading, Massachusetts, 1957).

9. Precision Measurement and Calibration, Statistical Concepts and Procedures, H. H. Ku, Ed., Volume 1, NBS Special Publication 300 (February

1969). [Available from Superintendent of Documents, U. S. Government

Printing Office, Washington, DC 20402]

10. Mandel, J., The Statistical Analysis of Experimental Error (Interscience, Wiley, New York, 1964). [A basic reference volume for error

analysis]

11. ASTM/IEEE Standard Metric Practice, ASTM E380-75 or IEEE Std. 268-1979.

[Available from the Institute of Electrical and Electronics Engineers,

Inc., 345 East 47 Street, New York, NY 10017]

15

!
y
NBS-114A (REV. 9-78)

U.S. DEPT. OF COMM. 1. PUBLICATION OR REPORT NO. BIBLIOGRAPHIC DATA

SHEET NBSIR 80-2060

4. TITLE AND SUBTITLE

Drafting Test Methods for Photovoltaic Systems

3. Recent' Accession No. |

'

M

5. Publication Date June 1980

7. AUTHOR(S)

William F. Lankford and Harry A. Schafft

8. Performing Organ. Report No.

mm

T - v

11. Contract/Grant No. SERI subcontract XP-9-8028-1; DOE

Con. No. EG-77-C-1-4042

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fsrreot. City, state, ZIP)

Solar Energy Research Institute Dept, of Energy

Quality Assurance & Standards Branch Photovoltaic Systems

Golden, CO 80401 Branch

Washington, DC 20545

13. Type of Report & Period Covered

15. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200-word or leas factual aummary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.)

General guidance and a step-by-step procedure are provided as aids in the development

of initial drafts of test methods for photovoltaic energy components and systems. It

is intended that these drafts will be referred to the appropriate technical

committees of organizations writing voluntary consensus standards. This approach is

designed to facilitate the expeditious development of consensus test method standards

for photovoltaic systems. The procedure is therefore designed to be compatible with

the requirements of existing standards organizations.

17. KEY WORDS (six to twelve entries ; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons) _ _ Consensus standards; measurement technology; photovoltaic energy conversion;

photovoltaics; solar cells; test method preparation.

18. AVAILABILITY [xj Unlimited

I I For Official Distribution. Do Not Release to NTIS

I I Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003- TO Order From National Technical Information Service (NTIS), Springfield,

VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

18

22. Price

$5.00

USCOMM-DC
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