5101-254

Flat-Plate Solar Array Project

DOE/JPL-1012-100

Distribution Category UC-63b

FSA Field Test Annual Report August 1 981 - January 1 984

Robert W. Weaver Robert H. Lee John D. Meyer L. Daniel Runkle

August 15, 1984

Prepared for

U.S. Department of Energy

Through an Agreement with National Aeronautics and Space Administration

by

Jet Propulsion Laboratory California Institute of Technology Pasadena, California

JPL Publication 84-52

Prepared by the Jet Propulsion Laboratory, California Institute of Technology, for the U.S. Department of Energy through an agreement with the National Aeronautics and Space Administration.

The JPL Flat-Plate Solar Array Project is sponsored by the U.S. Department of Energy and is part of the Photovoltaic Energy Systems Program to initiate a major effort toward the development of cost-competitive solar arrays.

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, com­pleteness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This publication reports on work done under NASA Task RE-152, Amendment 66, DOE/NASA IAA No. DE-AIOl-76ET20356.

ABSTRACT

During this reporting period the restructuring plan presented in the previous annual report was modified in response to budgetary pressures. The latter part of the period was marked by further budget reductions, which required a further curtailment of the Flat-Plate Solar Array (FSA) Project's field testing activities.

The modified plan was implemented with the following accomplishments: (1) six arrays containing Block IV modules were completed at the Jet Propulsion Laboratory (JPL) site, (2) the portable array data logger was completed and used at both the JPL site and at several non-JPL installations, and (3) a representative sample of Block I, II, and III modules were redeployed to the Goldstone site for continued endurance testing.

Those portions of the plan that were modified include: (1) a reduction in the number of Block IV modules deployed, (2) a reduced data acquisition schedule, (3) abandonment of the Table Mountain and Point Vicente sites, and (4) only a sample of the modules from the 12 continental remote sites underwent the final test procedures.

Current endurance data are presented for the remaining Block I, II, and III modules. These data indicate that more of these modules have failed or decreased in power output during this period. None of the Block IV modules under test during this period have failed, but 11 of the 155 deployed modules show reduced power output.

iii

CONTENTS

I. INTRODUCTION • • • • • • • • • • • • • • • • • • • • • • • • • • • 1-1

II.

III.

IV.

RESTRUCTURING PLAN IMPLEMENTATION

A. RESTRUCTURING PLAN ACCOMPLISHMENTS

1. Continental Remote Sites . . . . . 2. Southern California Sites . . 3. FSEC Site . . . . . 4. JPL Site . . . . . . . s. Data Loggers . . . . .

B. EXCEPTIONS TO THE RESTRUCTURING PLAN ••

1.

2.

3.

4.

Continental Remote-Site Module Disposition

Table Mountain and Point Vicente Sites

Block IV Modules at Goldstone Site

JPL Site

ENDURANCE DATA FOR BLOCKS I, II, AND III MODULES.

A.

B.

c.

CONTINENTAL REMOTE-SITE MODULES

1.

2.

Returned Modules

Final Measurements at JPL ••

GOLDSTONE RESULTS

BLOCK I, II, AND III UPDATE

BLOCK IV MODULE DEPLOYMENT AND TESTING.

A. MODULE INSTALLATION

1.

2.

Individual Modules

Array Modules •••

V

. . .

. . .

. . . . . .

. . . .

. .

. .

. .

2-1

2-1

2-1

2-1

2-3

2-3

2-4

2-4

2-4

2-4

2-4

2-4

3-1

3-1

3-1

3-1

3-1

3-3

4-1

4-1

4-4

4-4

v.

B.

c.

3.

4.

Cell Temperature Modules

Pre-installation LAPSS Data.

DATA ACQUISITION

1.

2.

JPL Site

FSEC Site

FIELD TEST RESULTS

1.

2.

JPL Site

FSEC Site

. . .

NON-JPL TESTING

A.

B.

c.

D.

INFRARED SCANNER AND I-V TESTS AT MCCC

INFRARED SCANNER TESTS AT FSEC

MODULE I-V DATA LOGGER TESTS

ARRAY I-V DATA LOGGER TESTS.

. . . . . . .

. . . . . . . .

4-4

4-4

4-7

4-7

4-14

4-14

4-14

4-15

5-1

5-1

5-1

5-1

5-2

VI. FUTURE PLANS • • • • • • • • • • • • • • • • • • • • • • • • • • • 6-1

REFERENCES • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 7-1

Figures

Tables

2-1.

3-1.

4-1.

4-2.

4-3.

2-1.

3-1.

Test Stands at the Florida Solar Energy Center

Failure Rates per Year for Blocks I, II, and III Modules • • • • • • • • • •

Layout of Jet Propulsion Laboratory Site

. . . . . .

Florida Solar Energy Center Site Layout ••

General Electric Hex-Shingle Cell Discoloration.

Implementation Schedule - Restructuring of Fields

Percent of Modules Producing Power in Ranges Expressed as a Percentage of Original Power for Modules From Continental Sites •••••

vi

2-3

3-3

4-2

4-3

4-16

2-2

3-2

3-2. Distribution of Power Output of Modules for Blocks I 'nlrough II I as a Percentage of Original Power as of August 1983 3-2

4-1. Block IV Module Deployment Schedule . . . . . . . . . 4-1

4-2. Internal Configuration and Pre-installation Data. 4-5

4-3. Array Electrical Characteristics . . . . . 4-6

4-4A. LAPSS Data Statistics for ARCO Block IV Modules . 4-8

4-4B. LAPSS Data Statistics for ASEC Block IV Modules . 4-9

4-4C. LAPSS Data Statistics for Motorola Block IV Modules . 4-10

4-4D. LAPSS Data Statistics for Photowatt Block IV Modules. 4-11

4-4E. LAPSS Data Statistics for Solarex Block IV Modules. . 4-12

4-4F. LAPSS Data Statistics for Spire Block IV Modules. . . . . . 4-13

vii

SECTION I

INTRODUCTION

The Flat-Plate Solar Array (FSA) Project field test task comprised five major activities during the reporting period from August 1981 through January 1984. Those activities were:

(1) Modification of the plan for restructuring the field test activities defined in FSA Field Test Annual Report August 1980-August 1981 (Reference 1-1) and the implementation of the modified plan.

(2) Acquisition of endurance data for the modules purchased under the Block I, II, and III tasks of the project that were redeployed to the Goldstone site.

(3) Completion of the installation of the Block IV modules at the Jet Propulsion Laboratory (JPL) site in Pasadena, California, and at the Florida Solar Energy Center (FSEC) site in Cape Canaveral, Florida. The array wiring scheme was completed and data acquisition was initiated.

(4) Completion of the portable array data logger by JPL instrumenta­tion personnel (Section 351) and a field checkout by field test personnel. The logger was used to obtain data at five non-JPL sites as well as data on the arrays at the JPL site.

(5) Changes in the operation of the JPL site.

This report covers the above major activities in detail and also discusses special test activities and the future plans for the FSA Field Test operations.

1-1

SECTION II

RESTRUCTURING PLAN IMPLEMENTATION

The restructuring plan, which was defined in FSA Field Test Annual Report for August 1980-August 1981, was modified to conform to the overall FSA Project objectives and to remain within the fiscal guidelines of the project. 'nle implementation schedule, shown in Table 2-1, was modified because of changes in module delivery schedules and technical problems in the data acquisition and array circuit control systems at the JPL field test site.

A. RESTRUCTURING PLAN ACCOMPLISHMENTS

1. Continental Remote Sites

All twelve continental remote sites were decommissioned as planned. All of the modules remaining at the sites were removed and returned to JPL with the exception of modules at the Albuquerque, New Mexico site. However, only a representative sample of the modules returned were remeasured in the large­area pulsed solar simulator (LAPSS). At the request of the United States Forest Service, the Mines Peak site was restored to its original condition in August 1983, thus eliminating the visual environmental impact of the test site.

2. Southern California Sites

All of the Block I, II, and III modules were removed from the Table Mountain site. 'nle performance data acquired for these modules during August 1981 were analyzed, and 38 of the original 82 modules were selected for redeployment to the Goldstone site: 20 from Block I, 10 from Block II, and 8 from Block III. nie criterion for redeployment was for the module to have degraded less than 1% from the original installed power output value. 'llle remaining modules were retired from the field test program and were placed in storage at JPL.

At the Goldstone site 40 of the original 80 Block I, II, and III modules deployed were selected for retention in the field environmental exposure program. The 40 modules were selected using the redeployment criterion mentioned above. 'nle remaining modules were placed in storage at JPL.

Of the 263 Block I, II, and III modules originally deployed at the JPL site, 73 were relocated to the Goldstone site, 33 were retained at JPL, and the remaining modules were placed in storage. Again, the redeployment criterion was used to select the modules for continued testing.

Therefore, there are 151 modules at the Goldstone test site, which represents a continuation of the Block I, II, and III endurance test program initiated in 1976. Data were obtained for these modules during August 1983, and the results are presented in Section III of this report.

2-1

N I

N

Table 2-1 Implementation Schedule - Restructuring of Fields

1981 1982

J F M A M J J A s 0 N D J F M A M J J A s 0 N D J

FORMULATE RESTRUCTURING Pl.AN .., DECOMMISSION CONTINENT AL REMOTE SITES

CONTRACT TO DECOMMISSION SITES ... --· •• .. SHIP MODULES ANO RECEIVE AT JPL ,~. •• .,, OBTAIN FINAL 1-V ILAPSSI DATA ~•- "

REORGANIZE SOUTHERN CALIFORNIA SITES

OBTAIN LAST SET OF IN-SITU 1-V DATA ,,. INST ALL NEW ST ANOS AT GOLDSTONE y

RELOCATE OLD MODULES AT GOLDSTONE y

MODIFY EXISTING ST ANOS FOR NEW MODULES .., ESTABLISH SITE AT FLORIDA SOLAR ENERGY CENTER y

TEST STANDS ERECTED .. MODULES INSTALLED y

REWIRE JPL SITE

REMOVE OLD WIRING T WIRE IN NEW MULTIPLEXER AND DORIC ST A TIONS y

CONNECT DORIC DEVICES • •• . .. , CONNECT MODULES TO MULTIPLEXERS • -•• ·- --1 •• ·- 1rli -I -· ·-~ FABRICATE/INSTALL ARRAY-SWITCHING CONTROLS • -..

FABRICATE ARRAY DATA LOGGER

DEFINE REQUIREMENTS ,,. COMPLETE DESIGN y

-CONSTRUCT ANO TEST --- •• li\ll --· •• ·--

DEPLOY NEW MODULES

RECEIVE MODULES FROM VENDORS -... -- .... •• --1 •• •• --1 •• •• __ , . ., DEPLOY MODULES AT ALL SITES .. i... •• •• _1_

• • •• --UPDATE JPL SITE SOFTWARE

MODIFY INSOL T AND SUMMARY TASKS • ·--.. REVISE DATA BASE FOR NEW MODULES • -· •• ·--•• •• ·--• CODE AND TEST ARRAY 1 AND SU MARS ~,

ST ART ROUTINE TESTING OF NEW MODULES y

1983

F M A M J J A s 0 N D

3. FSEC Site

Tne construction of the test stands at the Florida Solar Energy Center (FSEC) site in Cape Canveral, Florida, was completed in April 1982 . Six Block IV module s from each of the manufacturers (ARCO, ASEC, Motorola, Photowatt, Solarex, and Spire) were installed and subjected to performance measurements in October 1982. The performance of these modules was measured again in October 1983; results are presented in Section IV of this report. An overall view of t he s ite is shown in Figure 2-1.

4. JPL Site

The reorganization of the JPL test site was completed as planned. The site has been rewired to accommodate five intermediate-load arrays and one residential array. The installation of the modules was completed in November 1982; instrumentation and control circuits required to obtain module I-V data and to control the array configurations were completed in December 1982. Daily data acquisition began in January 1983. Test results from the JPL site are presented in Section IV of this report.

Figure 2-1. Test Stands at the Florida Solar Energy Center

2- 3

5. Data Loggers

Construction of the array data logger was completed in April 1982, and the laboratory test and checkout was conducted in May. Subsequent actual field use revealed an operational mode that caused the instrument to fail. 'Ibis defect was eliminated by altering the control circuits and revising the operating procedure. Tite logger was returned to service in August 1982 and has been used to obtain array-level data at six non-JPL installations as well as at the JPL site.

Tite module data logger, which has only module-level, data-acquisition capabilities, was also used during this period to obtain data for the United States Coast Guard at their test sites in Fort Lauderdale, Florida, and at Groton, Connecticut.

'lbe scope of the tests performed, using the loggers at non-JPL installa­tions, and the disposition of the data acquired during these tests are dis­cussed in Section V.

B. EXCEPTIONS TO THE RESTRUCTURING PLAN

1. Continental Remote-Site Module Disposition

'nte modules that were returned from the 12 continental remote sites after the sites were decommissioned were not all tested in the LAPSS facility at JPL. 'lhere were 145 modules at these sites prior to the sites being deconnnissioned and, in consideration of the work load scheduled for the LAPSS facility at that time, the decision was made to test only 35 of the returned modules instead of the entire set.

2. Table Mountain and Point Vicente Sites

'!he revised 1982 fiscal year budget for field testing led to the decision not to deploy any Block IV modules at these sites. 'lberefore, in effect, these sites were decommissioned.

3. Block IV Modules at the Goldstone Site

No Block IV modules were deployed at the Goldstone site because of budgetary considerations in FY 1982.

4. JPL Site

'lbe ARCO Solar residential array was not installed because the modules for this array were not purchased. 'lbe General Electric residential array was reduced to 80 modules because the allotted mounting area was not large enough to accommodate the 84 modules in the original plan.

2-4

SECTION III

ENDURANCE DATA FOR BLOCK I, II, AND III MODULES

Restructuring and program cutbacks reduced the number of modules retained in the endurance test site from 489 to 151. 'nlus, the data base for the evaluation of the endurance of Block I, II, and III modules has been significantly reduced. All the modules retained in the endurance test program are now mounted at the Goldstone site. The criterion for module failure is that it produce less than 75% of the original power.

A. CONTINENTAL REMOTE-SITE MODULES

1. Returned Modules

When the remote-site program was first initiated by NASA's Lewis Research Center., 180 modules were deployed at 12 sites. A description of these sites can be found in LSA Field Test Annual Report August 1978-August 1979, (Reference 3-1). Prior to the decommissioning of these sites, 26 modules were stolen, and four had been damaged by vandals. This left 150 modules, which were subject to evaluation for the effects of exposure. At the time of their return, two were known to have failed in an open-circuit condi­tion; and seven were producing less than 75% of the original power, which is the criterion for module failure.

2. Final Measurements at JPL

At the time these modules were returned to JPL, the measurements facility was overloaded with work, and a sample of only 35 of the 150 modules was measured in the LAPSS. The open-circuited and known low-power modules were not included, so the measurement of the 35 modules was considered representative of the remaining 141 modules. Assuming that this is the case, Table 3-1 shows the number of modules projected to be producing in a range of power output as a percentage of original pre-installation power.

During the 2.75 years of active exposure, it seems that 17 of the 150 modules would have failed. Therefore, 11% failed in a 2.75-year period, which results in a failure rate of 4.3% per year if uniform failure rate per-year is assumed.

B. GOLDSTONE RESULTS

From August 1981 to August 1983 a total of 22 modules installed at the Goldstone endurance site failed. Tile installed modules were Block I, II, and III, and they also showed varying amounts of power degradation. 'nle results for this two-year period are shown in Table 3-2. It is difficult to establish a trend from this data. However, it seems that at the end of the two-year period, the average Block I module had fallen the most in output power while the Block III module bad fallen the least, with the Block II module somewhere between. On the other hand, the percentage of failures in Block I and Block III were about equal and significantly higher than for Block II.

3-1

Table 3-1. Percent of Modules Producing Power in Ranges Expressed as a Percentage of Original Power for Modules from Continental Sites

Power Output as a Percent of Percent of Original Power Modules

90 to 100 51

85 to 90 27

80 to 85 8

75 to 80 3

Under 75 11

Table 3-2. Distribution of Power Output of Modules for Blocks I through III as a Percentage of Original Power as of August 1983

Power Output Block I Block II Block as a % of No. of No. of No. of

Original Power Modules % Modules % Modules

90 to 100 11 13 15 35 21

85 to 90 33 42 14 34 2

80 to 85 14 18 10 24 2

75 to 80 7 9 0 0 0

Under 75 14 18 3 7 5

Total 79 100 42 100 30

3-2

III

%

69

7

7

0

17

100

C. BLOCK I , II, AND II I UPDATE

The data obtained for the Block I, II and III modules at the Goldstone site in August 1983 have been combined with previous data for the modules to determine the endurance status as of August 1983. Figure 3-1 is a plot of the failure rates per year versus years in the field. 'lllese results are based on the number of unfailed modules in the field at the beginning of each year. The "R" symbols on the plot denote the time at which modules from the JPL and Table Mountain sites were redeployed to the Goldstone site. Note should be taken of the fact that at the time of redeployment all the modules in the field were producing a peak-power output within 1% of their original installed value. This means that the results since redeployment could be optimistic.

If the cumulative failures are used, unadjusted for failures, the results are as follows:

Block I: 33.2% failures in 6.75 years

Block II: 19.4% failures in 6.5 years

Block III: 17.0% failures in 5 years

BLOCK I 10

8

6

4

2

NOTES: 1. RA TES ARE BASED ON NUMBER OF UNFAILED MODULES IN THE FIELD AT THE BEG INN ING OF THE YEAR.

2. R1

II Ill DESIGNATES REDEPLOYMENT , , TIME TO GOLDSTONE SITE.

BLOCK Ill

I /

I I

/ /

/

r-­/

2

" / I V I '\

I I\ I I \

I I \ I l

I Rllv I

3 4

YEARS IN FIELD

5

BLOCK II

6

Figure 3-1. Failure Rates per Year for Blocks I, II, and II Modules

3-3

7

SECTION IV

BLOCK IV MODULE DEPLOYMENT AND TESTING

A. MODULE INSTALLATION

A total of 161 Block IV intermediate-load modules were deployed at the JPL and FSEC test sites on a schedule described in Table 4-1. At the JPL site 83 of these modules were installed in arrays, 36 were installed as individual modules, and 6 were installed for the purpose of obtaining cell-operating temperature data. 'nle layout of the JPL site is shown in Figure 4-1.

The FSEC site contains six modules from each of the Block IV manufacturers. 'llle layout of this site is shown in Figure 4-2.

Table 4-1. Block IV Module Deployment Schedule

1981 1982

i--~------~---~--~--+-J-hF:-+-M--+-A--1-~M~J JASON DJ FM AM J JASON D RECEIVE MODULES J i, ,c, , , •tr , r

OBTAIN LAPSS AND LASER-SCAN DAT A

OBTAIN LAPSS DATA FOR SANDSTROM CONSTANTS

RECEIVE SANDSTROM CONST ANTS

DEPLOY MODULES AT JPL

CONNECT MODULES TO MULTIPLEXERS

a y

I

C b d ,, ,r U'

a C b .... y

a C b ••• a C b . ,, ,,

a C

TY

I

e f y y

d e f ,, ,, y I

d e f y T ,Y

d I , y I ,,

d e f 1 Y a-ni ---ii

OBTAIN NEW REFERENCE CELLS I t-_______ ___:.::..:._ __ . ___ -+-+-4---1---1---J---+--+--l--l-~-l-,l.:··-+--+--+--!--+--+-+-+ 11 --4---+-__._~

START ROUTINE TESTING AT JPL

DEPLOY MODULES AT REMOTE SITES

t----GO_L_D_S_T_ON_E_~--~--~--~-...&..- DELETED

TABLE MOUNTAIN FROM

POINT VICENTE , , P~A~

CAPE CANAVERAL -FSEC

a· MOTOROLA ILA

b · G.E. RES

c · ARCO SOLAR/LA AUTOMA TEO ASSEMBLY

ARCO· SOLAR ILA d · SPIRE ILA

SOLAREX ILA

e · PHOTOWATT ILA

f . ARCO SOLAR RES ASECILA

4-1

a C , ~ _d_ _!_ -~ -- ---'-'.la--····~ y

SOLAREX ARRAY 22. MODULES, 1170 WATTS

3

SOLAREX ARRAY [CONT'D)

4 M-4 S-2 M-5

5

6 M-7 S-4 M-8

MOTOROLA ARRAY 2(? MODULES, 690WATTS

27

SPECIAL TESTS

r.E. RES1DENTIA1

ARRAY 84MODULES 1210WATTS

31

MATERIALS AND

MINIMODIJLES

INDIVIDUAL MODULES

ARRAY MODULES

TEMPERATURE·ONL Y MODULES

CONTROL MODULES

OLD MODULES

MULTIPLEXERS

ARRAY SWITCHES

N

TRACKER JUNCTION BOX

PYRANOMETER JUNCTION BOX

RESIDENTIAL· ARRAY JUNCTION SOX

SPECIAL JUNCTION BOX

CEU TEMPERATURE JUNCTION BOX

•ARCO SOLAR ARRAY USES AUTOMATED ASSEMBLY MODULES

Figure 4-1. Layout of Jet Propulsion Laboratory Site

4-2

ARCO SOLAR

SOLAREX I MOTOROLA I SPIRE II ___ A_s_E_c _______ J __ o_P_E_N_.J PHOTOWA TT I OPEN

N

Figure 4-2. Florida Solar Energy Center Site-Layout

1. Individual Modules

The individual modules at the JPL site were wired in an open-circuit condition so that they could be used as control modules that would not be subjected to the effects of a load. 'nlis means that these modules were not stressed during the test period and that any change in their performance would be due to an internal module problem, not to a load-related or operating-point condition.

'nle modules at the FSEC site are wired to fixed loads to simulate operation while being subjected to a hot-humid environment.

'lbe internal configuration of each module is described in Table 4-2. Also shown in the table are the pre-installation values for the short-circuit current (Isc), the open-circuit voltage (Voe), the peak power and the fill factor for each module. These values were determined from data taken in the LAPSS facility for a representative sample of each type of module at two module temperatures, 28° and 60°c, and 100 mW/cm2. Both sets of data are presented.

2. Array Modules

Five intermediate-load arrays and one residential array were installed at the JPL site. The number of modules, how they were wired, the array characteristics, and the fixed-load resistance are shown in Table 4-3. nie electrical characteristics in Table 4-3 were determined from the data taken in the LAPSS facility and the number of modules and the wiring configuration of each array.

3. Cell Temperature Modules

One module of each type was instrumented with at least three thermocouples on the backside of the module. When the modules were installed, there was one thermocouple behind a cell in the uppermost row of cells, one behind a cell in the middle of the module, and one behind a cell in the lowest row of cells. These modules were left in the open-circuit condition and were not wired to the I-V data acquisition system. 'nle three temperatures for each module type were sampled every time an I-V trace was taken for that particular type of module.

4. Pre-installation LAPSS Data

Prior to installation in the field, all modules are flashed in the LAPSS to give a baseline power measurement. In addition to this normal pro­cedure, a set of eight modules, selected at random from the modules provided by each vendor, was measured at both 28° and 6o0 c. The 28°c is the standard reference condition temperature for Block IV modules whereas the 60°C temperature represents a value more closely related to the actual

4-4

Table 4-2. Internal Configuration and Pre-installation Data

Characteristics

Nominal Outputa Nominal Output8

Configuration at 100 mW/cm2, 28°C at 100 mW/cm2, 60°c

No. of Diodes Cells Cells in Substrings Peak Peak

Modules per Series per in Parallel Blocks lsc• Voe• Power Fill NOCT, Isc• Voe• Power, Fill Type Module Substring per Block per Module STR Blk Hod A V w Factor oc A V w Factor

Intermediate

ARCO (Blk IV) 35 35 l 1 - - 1 2.4 19.3 33.2 0.701 ---------Not Tested----------

AMCO (Auto Assem.) 33 33 1 1 - - 1 2.4 18.2 30.6 0.700 53 2.5 17.0 28.4 0.681

ASEC 136 5 4 2 - - 1 55 5.5 17.9 71.0 o. 723 6 4 4 5.4 20.2 82.3 0.753

6 in series

Motorola 33 33 l 1 - - - 2,7 19,2 39.9 o. 771 56 2.7 17,0 34.3 0,740 _p,.. I

V, Photowatt 72 12 0 1 - - l 7.7 7.1 39.4 o. 725 54 7.8 6.2 33,5 0.694

Solarex 72 1 2 36 - 1 36 4,5 19.8 62.0 0.698 56 4.6 17.3 53.1 0.662

Spire 108 3 3 12 - - 2 3.8 26.3 58.7 0.757 56

Residential

GEb 19 19 1 l - - - 2.4 9.3 14.4 0.645 68 ---------Not Tested----------

Legend: 0 Cells aAverage of at least six samples.

D Blocks

Pl m bHanufacturer supplied data.

s ¢ ~ 2'""9 ~¢~

Note: All data, except for GE modules, taken in the LAPSS facility.

Table 4-3. Array Electrical Characteristics

Array Electrical Characteristics

Modules Array Fixed in Wiring Voe, Isc, Max. Power, Vmp, Imp, Load

Array Type Array Configuration V A w V A Resistor,

ARCO-Solar 18 All in series 306 2.s 510 236 2.2 107 (Auto. Assembly)

ASEC 12 All in series 215 5.5 850 167 5.1 33

Motorola 20 All in series 340 2.7 690 270 2.5 106

Photowatt 11 All in series 68 7.8 370 53 7.0 8 ::,. I

Solarex 22 All in series 380 4.6 1170 291 4.0 72 °'

General Electric 4 in parallel 186 9.6 1150 145 8.4 17

Resident ia 1 20 in series

8 At 100 mW/cm2 and 60°c base on module averages from Table 4-1.

operating temperature of the module. The nominal operating cell temperature (NOCT) is given in Table 4-2. The data for these tests are displayed in Table 4-4A through F, which also shows the data taken at 28°c for each of the six additional modules each that were provided to the Florida Solar Energy Center test site. These data, which comprise short-circuit current (Isc>, open-circuit voltage (V0 c), peak power (Wp), voltage at peak power (V2p), and fill factor, have been used to compute the mean value and standard devia­tion for each set. These results are included in Table 4-4.

Some observations can be made from these data. First of all, it seems that the module manufacturing processes used by all of the module suppliers produce uniform modules. Witness to this are the low standard deviations. Another observation is that the reduction in peak power and open-circuit voltage and the slight increase in short-circuit current resulting from operating at higher temperatures observed in earlier module designs and predicted by theory are clearly in evidence when the 2ao and 60°c cases are compared. No specific module from any of those tested is any better or worse than any of the others tested.

B. DATA ACQUISITION

Three distinct data acquisition systems were used to obtain the required performance data for the Block IV modules. The computer controlled system, as described in FSA Field Test Annual Report August 1980-August 1981 (Reference 4-1) was used to take module data at the JPL site. The array data logger was used to take the array-level data at the JPL site, and the module data logger was used at the FSEC site. The array data logger is described in the August 1980-August 1981 annual report, and the module data logger is described in the August 1979-August 1980 annual report.

1. JPL Site

a. Automated Module Data Acquisition. The data for the modules at the JPL site were acquired every day at solar noon by the computer­controlled, data-acquisition system. For each module programmed for test, an I-V scan was taken, the irradiance level was recorded as sensed by a reference cell made from the same cell material as the module's cells, and the three temperatures on the module of the same type were also recorded. Additionally, the irradiance level measured by an Eppley PSP, the air temperature, and the temperature of the specific reference cell being sampled were recorded.

These data were stored on a magnetic disk as they were obtained. After the sampling process was completed for all of the modules scheduled, the data system read the data from the disk, adjusted the I-V data to 100 mW/cm2, 28°c reference, and stored both the raw data and the adjusted data on the disk for printout at a later time. Periodically, the data were transferred to magnetic tape for permanent storage.

4-7

Table 4-4A. LAPSS Data Statistics for ARCO Block IV Modules

JPL Field Modules

28 deg C Tests

lsc Voe PK Pwr Vpp Fi 1 1 (Amps) <Volts) <Watts) <Volts) Factor

2.469 19.25 33.03 15.41 0.694 2.424 19.25 32.24 15. 15 0.690 2.394 19.01 32.96 15.09 0.724 2.456 19 .15 32.20 15.07 0.684 2.441 19.46 34.20 15.51 0.719 2.449 19.59 34.37 15.76 0.716 2.372 19.23 33.48 15.33 0.733 2.417 19 .13 33.11 14.99 0.716

MEAN 2.428 19.26 33.20 15.29 0.710 SIGMA .0327 0 .186 0.799 0.263 .0178

60 deg C Tests

I SC Voe Pk Pwr Vpp Fi 1 1 <Amps) <Volts> <Watts) (Volts) Factor

2.401 16.99 28.43 13. 18 0.696 2.489 17. 05 28.08 13. 10 0.661 2.446 1 7. 10 27.61 12.99 0.660 2.423 16.83 27.91 12.75 0.684 2,476 16.85 27.35 12.98 0.655 2.460 17. 19 29.09 13.38 0.687 2.466 1 7. 19 30.45 13.73 0.718 2.439 16.89 28.03 12.72 0.680

MEAN 2.450 17.01 28.37 13. 10 0.680 SIGMA • 0288 0 .145 0.991 0.333 .0212

FSEC Modules

I SC Voe Pk Pwr Vpp Fi 1 1 <Amps) (Volts) <Watts) (Volts) Factor

2.339 18.99 31.85 14.98 0.717 2.347 19.37 31 . 51 15.32 0.693 2.312 19. 12 32.43 15 .12 0.733 2.389 19.35 32.36 15.46 0.700 2.375 19.40 33 .15 15.48 0.719 2.364 19.42 33.24 15.44 0.724

MEAN 2.354 19.28 32.42 15.30 0.714 SIGMA .0276 0 .177 0.687 0.206 .0150

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Table 4-4B. LAPSS Data Statistics for ASEC Block IV Modules

JPL Field Modules

28 deg C Tests

I SC Voe Pl< Pwr Vpp Fi 1 1 <Amps> <Volts) (Watts) <Volts) Factor

5.200 20.22 80.47 16.22 0.765 5.300 20 .18 80.87 16.07 0.756 5.000 20.27 85.54 16.82 0.844 5.845 20.20 84 .15 16.67 0.712 5.209 20. 1 7 80.53 16.40 0.766 5.530 20.47 88.40 16.37 0.780

MEAN 5.347 20.25 83.33 16.43 0.771 SIGMA .2982 0. 113 3.266 0.278 .0428

60 deg C Tests

I SC Voe PK Pwr· Vpp Fi 11 (Amps) (Volts) (Watts) (Volts) Factor

5.261 17.72 67.36 13. 91 0.722 5.620 17.90 72.66 14.04 0.722 5.572 18.00 72.48 14.09 0.722 5.630 18.05 75.20 14.24 0.740 5.400 17.80 69.02 13.64 0.718 5.390 17.90 68.96 13.50 0.714

MEAN 5.479 17.90 70.95 13.90 0.723 SIGMA .1503 0 .122 2.963 0.282 .0089

FSEC Modules

I SC Voe PK Pwr Vpp Fi 11 <Amps) <Volts> <Watts> (Vol ts) Factor

5.342 20.46 83.97 16.68 0.768 5.318 20.53 84.68 16.65 0.775 5.256 20.45 83.34 16.68 0.775 5.307 20.56 83.57 16.64 0.765 5.364 20.56 83.97 16.99 0. 761 5.398 20.62 85.39 16.94 0.767

MEAN 5.331 20.53 84.15 16.76 0.769 SIGMA .0491 0.065 0.758 0 .158 .0056

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Table 4-4C. LAPSS Data Statistics for Motorola Block IV Modules

JPL Field Modules

28 deg C Tests

I SC Voe Pl< Pwr Vpp Fi 1 1 <Amps) (Volts) <Watts) (Volts) Factor

2.621 19.23 38.85 16. 16 0.770 2.662 18.86 39.00 15.52 0.776 2.764 19. 12 40.96 15.93 0.775 2.695 19.30 39.73 16 .16 0.763 2.754 19.20 40.43 15.91 0.764 2.760 18.87 39.59 15.36 0.760 2.683 19.56 40.70 16.34 0.775 2.675 19.55 40.84 16.29 0.780 2.744 19.41 40.86 16.36 0.767

MEAN 2.706 19.23 40.11 16.00 0.770 SIGMA .0510 0.257 0.829 0.359 .0069

60 deg C Tests

I SC Voe Pl< Pwr Vpp Fi 1 1 <Amps) (Volts) (Watts) (Volts> Factor

2.622 16.56 32.32 13 .1 7 0.744 2.691 16.75 33.35 13. 18 0.739 2.790 16. 91 34.84 13.62 0.738 2.776 17.05 34.65 13.62 0.732 2.779 16.68 33.68 13. 12 0.726 2.706 17.55 35.50 14. 13 0.747 2.710 17.42 35.42 13.96 0.750 2.753 17.09 34.76 13.72 0.738

MEAN 2.728 17.00 34.32 13.57 0.739 SIGMA .0571 0.350 1 .104 0.379 .0078

FSEC Modules

I SC Voe PK Pwr Vpp Fi 1 1 (Amps) <Volts) (Watts) <Volts) Factor

2.552 19. 15 37.85 16.27 0.774 2.511 18.77 37 .17 15.58 0.788 2.416 18.61 34.87 15.45 0.775 2.405 18.51 34.48 15.30 0.774 2.471 18.58 35.25 15.45 0.767 2.486 18.87 36.73 15.65 0.782

MEAN 2.474 18.75 36.06 15.62 0.777 SIGMA .0561 0.237 1. 375 0.342 .0073

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Table 4-4D. LAPSS Data Statistics for Photowatt Block IV Modules

JPL Field Modules

28 deg C Tests

I SC Voe Pl< Pwr Vpp Fi 11 <Amps) (Volts) <Watts) (Volts) Factor

7.670 7 .06 38.91 5.71 0.718 7.726 6.96 39.61 5.65 0.736 7.530 7 .08 38.71 5.68 0.726 7.818 7 .10 40.43 5.66 0.728 7.640 7 .07 39.33 5.78 0.728 7.774 6.97 39.28 5.55 0.724 7.821 7 .10 40.33 5.74 0.726 7.637 7 .08 38.45 5.66 0.711

MEAN 7.702 7. 05 39.38 5.68 0.725 SIGMA • 1015 0.056 0.718 0.069 .0074

60 deg C Tests

I SC Voe Pl< Pwr Vpp Fi 11 (Amps) (Volts> <Watts) <Volts) Factor

7.719 6.23 33.40 4.86 0.694 7.862 6 .18 33.46 4.84 0.688 7.847 6.25 34.04 4.88 0.694 7.710 6.23 32.71 4.84 0.680 7.892 6.25 34.35 4.83 0.696 7.826 6.25 34 .14 4.85 0.697 7.841 6 .17 34.01 4.83 0.702 7.495 6.23 32 .17 4.82 0.688

MEAN 7.774 6.22 33.54 4.84 0.692 SIGMA .1305 0.032 0.763 0.019 .0068

FSEC Modules

I SC Voe Pl< Pwr Vpp Fi 11 (Amps) <Volts) <Watts) (Volts) Factor

7.050 7.25 37.48 5.77 0.733 7.540 7.03 39.84 5.75 0.751 7.441 7 .17 39.95 5.87 0.748 7.503 7.08 38.85 5.70 0.731 7.466 7 .16 38.26 5.68 0.715 7.676 6.96 38.71 5.61 0.724

MEAN 7.446 7. 11 38.85 5.73 0.734 SIGMA .2108 0 .105 0.942 0.089 .0138

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Table 4-4E. LAPSS Data Statistics for Solarex Block IV Modules

JPL Field Modules

28 deg C Tests

Isc Voe Pl< Pwr Vpp Fi 1 1 (Amps) <Volts) <Watts) <Volts) Factor

4.534 20 .13 63.55 15.42 0.696 4.346 19.40 58.64 15.51 0.695 4.589 19.93 62.67 15.84 0.685 4.408 19.90 61.93 15.81 0.706 4.598 19.84 62.79 15.85 0.688 4.454 20 .02 63 .12 15.85 0.707 4.467 19.59 62.38 15.32 0.712 4.504 19.54 60.73 15.90 0.690

MEAN 4.488 19.79 61.98 15.69 0.697 SIGMA .0869 0.256 l. 594 0. 231 .0099

60 deg C Tests

Isc Voe Pl< Pwr Vpp Fi 1 1 <Amps) <Volts) <Watts) <Volts) Factor

4.671 17.58 54.53 13.55 0.664 4.528 16.83 50.37 12.80 0.660 4.711 17.38 53.23 13.37 0.650 4.591 17.34 52.89 13.44 0.664 4.762 17.29 53.54 13.44 0.650 4.597 17.49 53.81 13.49 0.669 4.610 17.24 53.41 12.95 0.672 4.665 17. 14 52.22 12.95 0.653

MEAN 4.642 17.29 53.00 13.25 0.660 SIGMA .0748 0.230 1.256 0.297 .0085

FSEC Modules

Isc Voe Pl< Pwr Vpp Fi 11 <Amps) (Volts> <Watts) (Volts> Factor

4.427 19. 71 62.18 15.79 0.712 4.242 19.51 58.33 15.67 0.704 4.470 19.84 63.03 15.74 0.710 4.264 19.79 60.43 15.67 0.716 4.437 19.88 62.89 15.79 0.712 4.341 19.80 62.11 16.29 0.722

MEAN 4.364 19.76 61.50 15.83 0.713 SIGMA .0959 0 .133 1. 806 0.234 .0060

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Table 4-4F. LAPSS Data Statistics for Spire Block IV Modules

JPL Field Modules

28 deg C Tests

I SC Voe Pk Pwr Vpp Fi l l (Amps) <Volts) <Watts) <Volts> Factor

3.802 20.26 58.68 16.05 0.761 3.809 20.36 59.07 15.84 0.761 3.770 20.26 59.23 16.05 0.775 3.881 20. 41 58.72 16.21 0. 741 3.837 19.99 57.93 15.40 0.755 3.835 20.38 59.20 15. 91 0.757 3.804 20.33 57.99 16.06 0.749 3.821 20.39 58.16 15.98 0.746

MEAN 3.820 20. 30 58.62 15.94 0.756 SIGMA .0326 0 .136 0.536 0.244 .0106

60 deg C Tests

I SC Voe Pk Pwr Vpp Fi l l <Amps) (Vol ts> <Watts) (Volts) Factor

3.838 17.79 47.87 13. 19 0.701 3.868 17.85 48.85 13.09 0.707 3.888 17.55 48 .10 12.65 0.704 3.922 17.93 48.59 13.22 0.690 3.825 17.89 49.46 13.71 0.722 3.843 17.94 49.20 13 .17 0.713 3.849 17.93 48.52 13 .12 0. 703 3.854 17.97 47.96 13. 12 0.692

MEAN 3.861 17.86 48.57 13. 16 0.704 SIGMA .0313 0 .136 0.580 0.287 .0104

FSEC Modules

Isc Voe Pk Pwr Vpp Fi l 1 (Amps) (Volts) <Watts> (Volts) Factor

3.594 20.38 57.97 16.33 0.791 3.647 20.32 57.67 16 .10 0.778 3.666 20.35 56.71 16.21 0.760 3.674 20. 41 58.56 16.24 0.780 3.765 20.30 57.68 15.81 0.754 3.763 20.29 57 .10 16. 21 0.747

MEAN 3.685 20.34 57.62 16 .15 0.768 SIGMA .0674 0.047 0.650 0 .182 .0172

4-13

b. Array-Data Acquisition. 'nle automated-data acquisition system cannot be used to acquire array-level data because of the high voltages and currents generated by the arrays. 'lllerefore, the array data logger, which was completed during this reporting period, was used to record the performance data for the arrays. 'lbese data were transferred to the computer for adjust­ment to the 100 mW/cm2, 28°c reference condition and were subsequently stored on a magnetic disk.

2. FSEC Site

a. Data Acquisition. 'Ihe module data logger was used to acquire the I-V data for the modules at the FSEC site on two separate occasions: at installation in October 1982 and in October 1983. 'Illese data were subsequently transferred to the computer, adjusted to the reference conditions mentioned above, and stored on a magnetic disk.

b. Weekly Inspection. FSEC and JPL have entered into a contract whereby a weekly inspection is performed by a trained person of the modules at their site. The inspection consists of a visual observation of the modules and making note of any changes from previous inspections. Additionally, the resistors that act as the load for each module are touched to determine if they are at an elevated temperature, which is an indication that the module is still functioning. 'lllese data are used in conjunction with the data obtained using the logger to determine the endurance characteristics of the modules.

C. FIELD TEST RESULTS

The Block IV modules have been in the field between 12 and 16 months as of this report. No failures have been observed, but some modules are not producing the same level of power they produced at the time they were installed. '!be results are presented below by site and wiring configuration. A variation in power output of 2% or less should not be considered a reduction in output because this level of change falls within the repeatability range of the instrumentation used to obtain the data. 1berefore, in the results discussed below no mention is made if the output level changed 2% or less.

1. JPL Site

a. Array Modules. None of the modules that were wired in the arrays failed. There are, however, three of these modules that show a reduc­tion in output during the test period. Two of the 22 Solarex modules are down 4% in output while one of the 11 Photowatt modules is down 6%. This means that 3.6% of the modules in the arrays are down in power output between 4 and 6%.

b. Arrays. None of the arrays has failed during the test period. In fact, none of the arrays show a loss in power output with the exception of the General Electric hex-shingle array. The GE array is down 4% in power output since it was installed. 'llle GE array was first operative in July 1982, five months before the other arrays. In October 1982 the collector

4-14

grids on the cells started to discolor. The discoloration became more pro­nounced for a period of about 5 weeks and then seemed to stabilize. It is not known if the discoloring is occurring on the grid itself or in the encapsulant that is in contact with the grid. Figure 4-3 shows what the cells looked like at installation and what they looked like in November 1982.

c. Individual Modules. There were no failures among the 36 unloaded, individually mounted Block IV modules. However, three of the modules were not producing as much power at the end of the test period as they were at the beginning. One Solarex module had a 4% reduction in output while two Spire modules were down by 5%.

d. Cell Temperature Modules. These modules are not used to determine performance changes in the modules; they are used to determine the cell-operating temperatures that are used to adjust the data to the standard conditions. The thermocouples were attached to the backside of the module substrate, not to the cells. As mentioned previously, there are three thermo­couples on each module, one near the top, one in the middle, and one at the bottom.

During the test period the ambient air temperature ranged between 14° and 36°c. The temperature data were used to make the following observations:

(1) nte top of any module was, with few exceptions, warmer than the middle or bottom. 'nle maximum difference recorded was 6°c, the minimum ooc, and the average was 2.7°c.

(2) The maximum difference between a recorded temperature and the air temperature was 37°c, the minimum was 21°c, and the average was 31.1°c.

(3) If only the highest module temperatures (the top of the module readings) are used, the maximum difference was 37°c, the minimum was 29°c, and the average was 32.8°c.

(4) If only the bottom-of-the-module readings are used, the maximum difference was 32°c, the minimum was 21°c, and the average was 29.5°c.

(5) Using the data recorded at the two extremes of air temperature (22°c), it was observed that the average difference between the module temperatures measured at the two extremes was 3.6°c. 'lllis indicates that the difference between the module temperature and the air temperature is not a strong function of the air temperature.

2. FSEC Site

a. Performance Data. There were no failures among the 36 modules at the site during the one-year test period. However, five of the

4-15

a) At Installation

-· b) November 1982

Figure 4-3. General Electric Hex- Shingle Cell Discoloration

4-1 6

modules are producing power at a lower level than at the start of the testing period. One Solarex module is down 6% in output, and four out of the six Spire modules are producing 8% less power.

b. Inspection Results. 'nle weekly inspections of the modules ·indicated that there is a minor amount of delamination occurring in the ASEC modules and some yellowing of the substrate material (this is also present in the modules at the JPL site).

4-17

SECTION V

NON-JPL TESTING

1be portable instrumentation equipment, 1-V loggers and IR (infrared) scanner, were used to conduct tests at eight non-JPL installations during this reporting period. Five tests were conducted using the array I-V logger, two using the module I-V logger, and two using the IR scanner.

A. INFRARED SCANNER AND 1-V TESTS AT MCCC

Tests using the IR scanner and the portable array logger were conducted at the Mississippi County Community College (MCCC) in Blytheville, Arkansas.

'llle installation at MCCC was a concentrating photovoltaic system using single-axis-tracking and parabolic-trough reflectors. The system had not been producing power at the expected level, and the tests were requested to deter­mine the cause. Results indicated that there were thermal gradients causing structural distortion, which in turn caused non-uniform illumination of the receiver. The result was t~at the system would act like a string of severely mismatched cells and thus produce a lower-than-expected power output. This was verified by using the portable array data logger to acquire I-V curves under the same conditions that the IR data were acquired. 1be I-V data revealed that, as the illumination on the receiver changed, the power output varied by as much as 60%. In many cases the curves indicated that some of the cells were actually going into a back-biased condition. The cell strings were protected by diodes; when the problem became severe enough, the diodes did function. 1bis was verified by using the IR scanner to monitor the temperature of the diodes when a back-biased condition was thought to exist.

The data from these tests were compiled and, along with a preliminary analysis, were given to the operations group at MCCC.

B. INFRARED SCANNER TESTS AT FSEC

1be IR scanner was used at the Florida Solar Energy Center to determine if the experimental residential system had changed characteristics relative to the cell operating temperatures recorded during the tests that were performed in early 1981. The results indicated that there were only minor differences in the two sets of results. The results of the tests were reported to FSEC.

C. MODULE I-V DATA LOGGER TESTS

Tile module I-V data logger was used to conduct tests for the United States Coast Guard at two of their module-testing stations, one in Groton, Connecticut, and the other in Fort Lauderdale, Florida. 1-V curves were recorded for over 280 modules at the two sites. These data were returned to JPL for reduction, tabulation, and plotting. In the reduction process the data were adjusted to two different irradiance levels, 100 and 80 mW/cm2 , at 28°c. All of the results were furnished to the Coast Guard for their further analysis.

5-1

D. ARRAY I-V DATA LOGGER TESTS

'llle array I-V data logger was used to conduct five tests of non-JPL arrays. 'llle testing done for MCCC was described above. 1lte other four were conducted for the San Diego Gas and Electric Company (SCGE); AMOCO Oil Company in Naperville, Illinois; San Diego State University (SDSU); and at Acurex Corporation in support of the SMUD project.

The SDGE and SDSU installations are both residential applications of a flat-plate solar photovoltaics system. Both systems use ARCO modules with a design output of 2 kW.

The SDGE system is a retrofit installation on a house owned by SDGE and is being used as a test-bed system to determine the overall feasibility of integrating residential systems into their grid system. The testing was conducted to (1) determine if the array was operating properly and (2) to acquire data that could be compared to the data that was being recorded by SDGE for their studies. SDGE was furnished with the raw data in both plotted and tabulated form on site.

The SDSU system is an integrated installation on a model home in the Scripps Ranch Development near San Diego, California. 1lte purpose of the tests was to furnish SDSU with data that would verify their data acquisition system accuracy. 'lbe data were presented in raw form, both plotted and tabulated.

AMOCO Oil Company has installed a 5-kW system at one of their service stations near Naperville, Illinois. 'nley have a data system that takes array output data and irradiance data and performs an energy accounting function that keeps track of the energy produced by the array and the amount of energy that the system gets from the utility grid. The tests were conducted to determine if the array was performing properly and if there was any degrada­tion in the array. I-V data were taken for each of five subarrays and for the whole system. The results indicated that one of the subarrays was performing at a level 28% below the other four. 'llle data were plotted and tabulated for AMOCO.

The tests conducted at Acurex Corporation were in support of JPL's Technical Assistance Team which was, in turn, supporting SMUD in technical matters in connection with their multi-megawatt project. The data acquired were compared to the data acquired by an on-site data system to determine the accuracy of that data system. When the data were compared, it was discovered that there were some differences in the peak-power voltage values. An analysis of the different data acquisition processes was conducted, and it was determined that the differences in the data were due to the data acquisition rates and sequence. The results and subsequent analysis of these tests indicated that, if accuracy is to be maintained, the voltage and current values must be recorded simultaneously when a system that scans across the ranges of current and voltage is used.

5-2

SECTION VI

FUTURE PLANS

The field test activities have been reduced because of a change in scope and purpose of these activities within the FSA Project. 'lbe key changes are:

(1) 'lbe daily acquisition of 1-V data for all modules in the JPL field test site will no longer be performed. 'nlese data will be acquired on an as-required basis but at least once per month.

(2) Weather and irradiance data will not be acquired except on demand and during the 1-V data acquisition process.

(3) Array data at the JPL site will only be taken on demand.

'Ille acquisition of data for the Block IV modules at the FSEC site; for the Blocks I, II, and III modules at the Goldstone site; and for the Block II modules at Albuquerque will continue on a six-month basis.

6-1

REFERENCES

1-1. Jaffe, P., Weaver, R.W., and Lee, R.E., FSA Field Test Annual Report August 1980-August 1981, JPL Publication 81-99, (5101-197), DOE/JPL-1012-59, Jet Propulsion Laboratory, Pasadena, California, December 15, 1981.

3-1. Jaffe, P., LSA Field Test Annual Report August 1978-August 1979, JPL Publication 80-5, (5101-141), DOE/JPL-1012-38, Jet Propulsion Laboratory, Pasadena, California, December 15, 1979.

4-1. Jaffe, P., Field Test Annual Report August 1979-August 1980, JPL Publication 81-12, (5101-166), DOE/JPL-1012-52, Jet Propulsion Laboratory, Pasadena, California, December 30, 1980.

7-1