JE

Tj measurement of bypass diode for PV modules

( J-TG 4 activities of QA Forum QA Task Force 4 Diode Shading amp Reverse Bias )

This work was performed in cooperation with Onamba SankenElectric Nihon Inter Electronics Kyocera and SHARP

Feb 24-25 2015　13 Denver Colorado USA Yasunori Uchida

JET (Japan Electrical Safety amp Environment Technology Laboratories)

In the bypass diode (BD) thermal test required by IEC61215 Cl1018 and IEC61646 Cl1018 it is necessary to measure the junction temperature (Tj) of theBD But it is not possible to measure it directly

Two methods are conceivable which are ldquoVf-Tj methodrdquo and ldquoTlead method (or Tcase method)rdquo

ldquoVf-Tj methodrdquo is based on the physical characteristics ofthe diode where the Vf (at certain forward current If) andthe Tj are related

Thus ldquoVf-Tj methodrdquo is considered as a primary method

1

In the bypass diode (BD) thermal test required by IEC61215 Cl1018 and IEC61646 Cl1018 it is necessary to measure the junction temperature (Tj) of theBD But it is not possible to measure it directly

Two methods are conceivable which are ldquoVf-Tj methodrdquo and ldquoTlead method (or Tcase method)rdquo

ldquoVf-Tj methodrdquo is based on the physical characteristics ofthe diode where the Vf (at certain forward current If) andthe Tj are related

Thus ldquoVf-Tj methodrdquo is considered as a primary method

1

ldquoTlead methodrdquo in comparison is considered as a secondary method Because it uses the parameter Rth (thermal resistance) to relate the lead temperature to the junction temperature

ldquoTlead methodrdquo is commonly used because of its simplicity But it may involve larger error

This paper deals with the analysis and the experiments about how much error ldquoTlead methodrdquo may have

2

In ldquoVf-Tj methodrdquo it is necessary to obtain first the Vf-Tj characteristicsrdquo which is practically linear as shown below The formula to show the characteristics will change by an individual diode and the forward current applied

An example of Vf-Tj characteristics

Tj = -88552 X Vf + 40795

3

Vf-Tj characteristic (at If=9A) of a BD

Vf V

Tem

p

4

The relation between Tj and Tlead is expressed as below using the parameter of thermal resistance (Rth) Tj = Tlead + ( Vf timesIftimesRth ) The value of Rth is usulally supplied by the diode manufacturer The problem is that the value supplied is not a real Rth but an apparent value of Rth which will vary according to the heat dissipating condition where the diode is installed (see next slide)

Axial type diode13

13

　　　　 Thermal source (Diode junction) 13 P = Vf X If Apparent Rth will vary according to the heat flow ratio which varies with the radiation condition of each route

Tj = Tlead + VftimesIf times Cc times Rth(real) rarr13 Rth(apparent)13

C13

B13

A13 Ambient13

Rc-113

Ra-113

Rb-113

Rc-213

Ra-213

Rb-213

A anode13

B body13

C cathode13

2-3 Heat flow and Rth13

Cc heat flow rate on the cathode side13

Ca heat flow rate on the anode side

Cb heat flow rate on the diode body13

presented at NREL PVMR Work-shop 2013 Thermal resistance varies by the difference of heat dissipating condition such as a J-box13

6

The purpose is to compare the Tj (Tj2) obtained by the Vf-Tj method and the Tj which is determined by the Tlead method from the Rth values supplied by the diode manufacturerldquo(Tj1) The procedure is as follows 13➊ After applying forward current(If=9A) to the diode for one hour 　　the forward voltage(Vf) and Tlead are measured

➋ By using Rth supplied by diode manufacturer the junction temperature (Tj1) is calculated by Tlead method Tj1 = Tlead + Rth-d x Vf x If

➌ By using ldquothe functional formula between Vf and Tjrdquo obtained from the 13 　13 Vf-Tj characteristic Tj2 is calculated Tj2 = atimesVf + b a and b are the characteristic constants 13

➍ Tj1 and Tj2ldquo are compared 13

7

Four different types of BD were incorporated in the J-boxes BD-1 BD-3 and BD-4 are axial type diodes BD-5 is a surface mount type diode (TO-220) All J-boxes are potted by Si resin Thermocouples were attached as indicated by the manufacturer for example 3mm from the diode body BD-13413

TO-220 diode13

BD-513

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

In ldquoVf-Tj methodrdquo it is necessary to obtain first the Vf-Tj characteristicsrdquo which is practically linear as shown below The formula to show the characteristics will change by an individual diode and the forward current applied

An example of Vf-Tj characteristics

Tj = -88552 X Vf + 40795

3

Vf-Tj characteristic (at If=9A) of a BD

Vf V

Tem

p

4

The relation between Tj and Tlead is expressed as below using the parameter of thermal resistance (Rth) Tj = Tlead + ( Vf timesIftimesRth ) The value of Rth is usulally supplied by the diode manufacturer The problem is that the value supplied is not a real Rth but an apparent value of Rth which will vary according to the heat dissipating condition where the diode is installed (see next slide)

Axial type diode13

13

　　　　 Thermal source (Diode junction) 13 P = Vf X If Apparent Rth will vary according to the heat flow ratio which varies with the radiation condition of each route

Tj = Tlead + VftimesIf times Cc times Rth(real) rarr13 Rth(apparent)13

C13

B13

A13 Ambient13

Rc-113

Ra-113

Rb-113

Rc-213

Ra-213

Rb-213

A anode13

B body13

C cathode13

2-3 Heat flow and Rth13

Cc heat flow rate on the cathode side13

Ca heat flow rate on the anode side

Cb heat flow rate on the diode body13

presented at NREL PVMR Work-shop 2013 Thermal resistance varies by the difference of heat dissipating condition such as a J-box13

6

The purpose is to compare the Tj (Tj2) obtained by the Vf-Tj method and the Tj which is determined by the Tlead method from the Rth values supplied by the diode manufacturerldquo(Tj1) The procedure is as follows 13➊ After applying forward current(If=9A) to the diode for one hour 　　the forward voltage(Vf) and Tlead are measured

➋ By using Rth supplied by diode manufacturer the junction temperature (Tj1) is calculated by Tlead method Tj1 = Tlead + Rth-d x Vf x If

➌ By using ldquothe functional formula between Vf and Tjrdquo obtained from the 13 　13 Vf-Tj characteristic Tj2 is calculated Tj2 = atimesVf + b a and b are the characteristic constants 13

➍ Tj1 and Tj2ldquo are compared 13

7

Four different types of BD were incorporated in the J-boxes BD-1 BD-3 and BD-4 are axial type diodes BD-5 is a surface mount type diode (TO-220) All J-boxes are potted by Si resin Thermocouples were attached as indicated by the manufacturer for example 3mm from the diode body BD-13413

TO-220 diode13

BD-513

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

4

The relation between Tj and Tlead is expressed as below using the parameter of thermal resistance (Rth) Tj = Tlead + ( Vf timesIftimesRth ) The value of Rth is usulally supplied by the diode manufacturer The problem is that the value supplied is not a real Rth but an apparent value of Rth which will vary according to the heat dissipating condition where the diode is installed (see next slide)

Axial type diode13

13

　　　　 Thermal source (Diode junction) 13 P = Vf X If Apparent Rth will vary according to the heat flow ratio which varies with the radiation condition of each route

Tj = Tlead + VftimesIf times Cc times Rth(real) rarr13 Rth(apparent)13

C13

B13

A13 Ambient13

Rc-113

Ra-113

Rb-113

Rc-213

Ra-213

Rb-213

A anode13

B body13

C cathode13

2-3 Heat flow and Rth13

Cc heat flow rate on the cathode side13

Ca heat flow rate on the anode side

Cb heat flow rate on the diode body13

presented at NREL PVMR Work-shop 2013 Thermal resistance varies by the difference of heat dissipating condition such as a J-box13

6

The purpose is to compare the Tj (Tj2) obtained by the Vf-Tj method and the Tj which is determined by the Tlead method from the Rth values supplied by the diode manufacturerldquo(Tj1) The procedure is as follows 13➊ After applying forward current(If=9A) to the diode for one hour 　　the forward voltage(Vf) and Tlead are measured

➋ By using Rth supplied by diode manufacturer the junction temperature (Tj1) is calculated by Tlead method Tj1 = Tlead + Rth-d x Vf x If

➌ By using ldquothe functional formula between Vf and Tjrdquo obtained from the 13 　13 Vf-Tj characteristic Tj2 is calculated Tj2 = atimesVf + b a and b are the characteristic constants 13

➍ Tj1 and Tj2ldquo are compared 13

7

Four different types of BD were incorporated in the J-boxes BD-1 BD-3 and BD-4 are axial type diodes BD-5 is a surface mount type diode (TO-220) All J-boxes are potted by Si resin Thermocouples were attached as indicated by the manufacturer for example 3mm from the diode body BD-13413

TO-220 diode13

BD-513

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

13

　　　　 Thermal source (Diode junction) 13 P = Vf X If Apparent Rth will vary according to the heat flow ratio which varies with the radiation condition of each route

Tj = Tlead + VftimesIf times Cc times Rth(real) rarr13 Rth(apparent)13

C13

B13

A13 Ambient13

Rc-113

Ra-113

Rb-113

Rc-213

Ra-213

Rb-213

A anode13

B body13

C cathode13

2-3 Heat flow and Rth13

Cc heat flow rate on the cathode side13

Ca heat flow rate on the anode side

Cb heat flow rate on the diode body13

presented at NREL PVMR Work-shop 2013 Thermal resistance varies by the difference of heat dissipating condition such as a J-box13

6

The purpose is to compare the Tj (Tj2) obtained by the Vf-Tj method and the Tj which is determined by the Tlead method from the Rth values supplied by the diode manufacturerldquo(Tj1) The procedure is as follows 13➊ After applying forward current(If=9A) to the diode for one hour 　　the forward voltage(Vf) and Tlead are measured

➋ By using Rth supplied by diode manufacturer the junction temperature (Tj1) is calculated by Tlead method Tj1 = Tlead + Rth-d x Vf x If

➌ By using ldquothe functional formula between Vf and Tjrdquo obtained from the 13 　13 Vf-Tj characteristic Tj2 is calculated Tj2 = atimesVf + b a and b are the characteristic constants 13

➍ Tj1 and Tj2ldquo are compared 13

7

Four different types of BD were incorporated in the J-boxes BD-1 BD-3 and BD-4 are axial type diodes BD-5 is a surface mount type diode (TO-220) All J-boxes are potted by Si resin Thermocouples were attached as indicated by the manufacturer for example 3mm from the diode body BD-13413

TO-220 diode13

BD-513

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

6

The purpose is to compare the Tj (Tj2) obtained by the Vf-Tj method and the Tj which is determined by the Tlead method from the Rth values supplied by the diode manufacturerldquo(Tj1) The procedure is as follows 13➊ After applying forward current(If=9A) to the diode for one hour 　　the forward voltage(Vf) and Tlead are measured

➋ By using Rth supplied by diode manufacturer the junction temperature (Tj1) is calculated by Tlead method Tj1 = Tlead + Rth-d x Vf x If

➌ By using ldquothe functional formula between Vf and Tjrdquo obtained from the 13 　13 Vf-Tj characteristic Tj2 is calculated Tj2 = atimesVf + b a and b are the characteristic constants 13

➍ Tj1 and Tj2ldquo are compared 13

7

Four different types of BD were incorporated in the J-boxes BD-1 BD-3 and BD-4 are axial type diodes BD-5 is a surface mount type diode (TO-220) All J-boxes are potted by Si resin Thermocouples were attached as indicated by the manufacturer for example 3mm from the diode body BD-13413

TO-220 diode13

BD-513

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

7

Four different types of BD were incorporated in the J-boxes BD-1 BD-3 and BD-4 are axial type diodes BD-5 is a surface mount type diode (TO-220) All J-boxes are potted by Si resin Thermocouples were attached as indicated by the manufacturer for example 3mm from the diode body BD-13413

TO-220 diode13

BD-513

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

8

Tj values indicated below show the measured results and the difference between ldquoTj1rdquo and ldquoTj2rdquo

Kind of BD13 Tj1 Tj2 Tj2 ndash Tj113

BD-1 axial13 151713 159813 8113 BD-3 axial13 150213 162113 11913

BD-4 axial13 151813 157713 5913

BD-5 TO-22013 100813 108513 7713

The test results showed the difference about 10

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

BD ID13 ➊ Presented by diode manufacturer13 ➋13 Single BD13 ➌ In J-box13

BD-113 2513 4513 5813

BD-313 3513 6313 9213

BD-413 2513 3913 4613

9

Actually Rths from the values obtained by the above measurement (②amp③) are different to the values supplied by the manufactures This indicates the risk of using ldquoRth values ①rdquo supplied by diode manufacturer

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

10

The measurements cooperatively made by other organizations (a diode manufacturer and a module manufacture) confirmed that the similar results were be obtained 13 13 Rth (W) JET vs Diode manufacturer A sample Axial diode V-1

13 13 Rth (W) JET vs PV module manufacturer A sample Axial diode V-2

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by diode

manufacturer A13

2513 5A13 2313 3213 9A13 3013 3513 11A13 3213 3413

➊ Rth supplied by diode manufacturer V13

at forward current (If)13 ➋ Rth by JET13 ➌ Rth by PVm

Manufacturer A13

2513 5A13 4713 3013 9A13 4913 3813 11A13 4913 3713

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests

11

diams The test results showed that about 1013 difference may exist between the calculated Tj by ldquoTlead methodrdquo and the real Tj (Tj measured by Vf-Tj method) diams This difference could not be overlooked It is considered appropriate to revise the pass criteria of the test to have 10 margin to the diode manufacturerrsquos maximum junction temperature rating in the case of the ldquoTlead methodrdquo is used diams It is recommended and considered desirable to apply the ldquoVf-Tj methodrdquo as far as possible as a better method of measurement diams It would be desirable if other organizations could perform the 　 similar tests