SEMI International Standards
Standards New Activity Report Form (SNARF)
Date Prepared: 09/06/2016Revised (if Applicable):

Document Number: 6112
SNARF for: New Standard: Specification for Voltage Sweep Time and Direction in Transient Mode I-V Measurement of Silicon Solar Cells

Originating Global Technical Committee: Photovoltaic
Originating TC Chapter: China
Task Force (TF) in which work is to be carried out: Crystalline Silicon Solar Cell Task Force
Note: If a new task force is needed, also submit a task force organization form (TFOF)

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1. Rationale:
a. Describe the need or problem addressed by this activity.
(Indicate the customer, what benefits they will receive, and if possible, quantify the impact on the return on investment [ROI] if the Document is implemented.)
In recent years, the photovoltaics solar energy industry continues to develops at a high speed, and the market share of PV energy is increasing year by year. This motivates a fast development and improvement of PV related science and techniques. As a relatively new research field, research in PV related area is changing from product based research to new technique research and scientific study. It is now the start of a golden age for PV study, with support from both research institutes and manufacturers.
As silicon solar cell structures become more complicated, there is a compelling requirement for more accurate measurement techniques. Solar cell measurement standards in early days focus on details such as light source, measurement temperature, and calibration methods. A good example is the IEC60904-1 series, which was formalized in 2006. However, as more new cell designs appear in the market within this decade, higher technical standards for measurement methods are required. This is the main motivation for this proposal to standardize the exposure time and voltage sweep direction for solar cell performance measurement. These two factors are not included in any previous standards. However, some studies on solar module measurements have shown that the exposure time difference may lead to obvious power output variations. N- and p-type modules have shown different parameters when the sweep direction is different. Further investigation also reveals that solar cell measurement results are affected by the exposure time parameter, and the output difference is more significant than the module products.
An example can be found from a typical p-type PERC cell. When the cell is swept from Isc to Voc,, the fill factor (FF) measured at 150 ms exposure time can become higher by up to 0.4% (absolute value) than the one measured at 40 ms. Contrarily, when the cell is swept from Voc to Isc, FF at150 ms exposure time can be smaller than the FF at 40 ms by up to 0.5%.
The fluctuation in FF is closely related to the length of exposure time. This phenomenon is called “capacitance effect” in the literature. The capacitance effect is not very significant on traditional screen printed multi-crystalline cells with aluminum back surface fields. However, most of the high efficiency cells developed in recent years is found to show this capacitance effect. N-type passivated emitter rear totally diffused (PERT) cells show a FF difference between forward and reverse voltage sweep. When the exposure time is set at 40 ms, the difference can be as high as 1.5% (absolute value). As the exposure time increases, the FF difference reduces until it reaches almost zero or becomes saturated. However, the critical exposure time value to reach saturation depends on cell structure. For example, the exposure times for n-PERT and HIT cell saturation are 130 ms and 200 ms respectively.
In summary, to accurately measure crystalline silicon solar cells in transient mode IV testing, a standard for exposure time and sweep direction setting is necessary. This standard is important when we compare the performance of similar cells from different manufacturers, where a uniform measurement method is urgently required.


b. Estimate effect on industry.
1: Major effect on entire industry or on multiple important industry sectors - identify the relevant sectors
Sector or Company Information: Wafers slicing, solar cell manufacture, Module manufacture, PV System manufacture

c. Estimate technical difficulty of the activity.
II: Some Difficulty - Disagreements on known requirements exist but developing consensus is possible

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2. Scope:
a: Describe the technical areas to be covered or addressed by this Document development activity. For Subordinate Standards, list common concepts or criteria that the Subordinate Standard inherits from the Primary Standard, as well as differences from the Primary Standard:
This standard applies to IV performance measurements of p- and n-type crystalline solar cells where the transient mode illumination is used.
This standard mainly includes the following technical contents:
1. For p-type and n-type cells, the voltage sweep direction (forward or reverse) is provided respectively.
2. For different cell structures, the required exposure time setting is provided.
3. For measurement equipment which cannot fulfill the exposure time requirements due to technical reasons, this standard provides suggested empirical algorithms.

b: Expected result of activity
New Standard or Safety Guideline (including replacement of an existing Standard or Safety Guideline)

For a new Subordinate Standard, identify the Primary Standard here:




For Standards, identify the Standard Subtype below:
Specification

Miscellaneous (describe below):

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3. Projected Timetable for Completion:

a: General Milestones
a. Activity Start: 11/01/2016b. 1st Draft by: 04/01/2017
c. (Optional) Informational Ballot by: 06/01/2017d. Letter Ballot by: 12/01/2017
e. TC Chapter Approval By:03/01/2018

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4. Liaisons with other Global Technical Committees/TC Chapters/Subcommittees/TFs:
a. List SEMI global technical committees, TC Chapters, subcommittees, or task forces in your or other Regions/Locales that should be kept informed regarding the progress of this activity. (Refer to SEMI Standards organization charts and global technical committee charters and scopes as needed.)
Photovoltaic (PV) - Material, PV module task force

b. List any planned Type I Liaisons with external nonprofit organizations (e.g., SDO) that should receive Draft Documents from Standards staff for feedback during this activity and be notified when the Letter Ballot is issued (refer to Procedure Manual § 7):


c. Intercommittee Ballots:
will not be issued

Identify the recipient global technical committee(s):
Photovoltaic
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5. Safety Considerations:
The resulting document is expected:
NOT to be a Safety Guideline

NOTE FOR "to be a Safety Guideline": When all safety-related information is removed from the Document, the Document is NOT technically sound and complete - Refer to Section 15.1 of the Regulations for special procedures to be followed.

NOTE FOR "NOT to be a Safety Guideline": When all safety-related information is removed from the Document, the Document is still technically sound and complete.

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6. Intellectual Property Considerations:
Note: Both a: and b: below should be checked for Revision of existing Standard(s) and Safety Guideline(s).

a. For a new Standard or Safety Guideline and for any part to be modified or added in a Revision of published Standards and Safety Guidelines:
the use of patented technology is NOT required.

If "patented technology is intended to be included in the proposed Standard(s) or Safety Guideline(s) " is selected above, then also check one:


b. For Revision, Reapproval, Reinstatement, or Withdrawal of existing Standard(s) and Safety Guideline(s):
there is no known material patented technology necessary to use or implement the Standard(s) and Safety Guideline(s)

c. The body of the Document and any Appendices, Complementary Files, Related Information sections, or Various Materials that may or may not be a part of the Document by reference:
will NOT include reproduced copyrighted material



NOTE FOR ‘the use of patented technology or the incorporation of Copyrighted Item(s) is NOT required’: If in the course of developing the Document, it is determined that the use of patented technology or Copyrighted Item(s) is necessary for the Document, the provisions of Regulations § 16 must be followed.

NOTE FOR ’will incorporate Copyrighted Item’: A copyright release letter must be obtained from the copyright owner prior to publication.

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7. Comments, Special Circumstances:
None.

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8. TC Member Review:
took place between (put dates below ) before approval at the TC Chapter Meeting, or

Member Review Start Date; 10/28/2016
Member Review End Date: 11/10/2016

NOTE FOR ‘TC Member Review’ is required by the Regulations for a period of at least two weeks
before approval of a new, or a major revision of an existing, Standard or Safety Guideline. (Refer to Regulations ¶ 8.2.1)
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9. SNARF Approval Dates:
TC Chapter or GCS11/25/2016
Recorded in TC Minutes12/09/2016

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10. SNARF Extension Dates:
TC Chapter Extension Granted on
Extension Expires on