Indoor PV

Ozcan Bazkir, Seval Meric

Introduction

Emerging Photovoltaic (PV) devices, such as dye sensitized solar cell (DSSC), perovskite solar cell (PSC), organic photovoltaic (OPV) which are also called third generation PV devices has attracted great attention recently. They have been used to meet the energy needs of the devices in applications such as smart homes, smart roads, the internet of things etc. These applications have become popular in recent years and seem to take place more and more in our lives in the near future. The energy needs of these devices are vital for the uninterrupted operation of devices which are in communication with each other. Most importantly, such devices must become independent of electric grid and wired power as they will integrate with wireless communication systems. Therefore, it requires a self-sustainable power source and it is also crucial to find an energy source that operates under low light indoor conditions. To supply energy to these devices various works have been done to find a new energy sources other than nonrenewable energy sources. Efforts to produce energy from solar radiation using PV devices have been widely carried out. In these applications, mostly first (Single c-Si, Multi c-Si) and second generation (a-Si, CIGS, CdTe) PV devices have been used, which are more efficient at outdoor applications as their spectral responsivities match well with the spectra of sunlight in the ultraviolet, visible and near infrared regions (Figure 1). For this reason they are also called outdoor PV devices. However, the efficiencies of these outdoor PV devices are low under artificial indoor light sources having radiation only in the visible region. Since the responsivities of emerging PV devices match well with the spectra of artificial light sources (Fluorescent, Incandescent, LED), they have been used to supply energy to the devices used indoor applications (Figure 2) and they are called as indoor PV devices.

Figure1. Spectral distribution of AM.1.5 and spectral responsivity of c-Si based WVPS

The use of indoor PV devices and therefore their market volume has been increased rapidly. The financial equivalent of this high level market volume reaches billions of dollars. For this reason, the needs for the metrology of these devices have been increasing in parallel with the market volume. These needs can easily be seen in the studies carried out in metrology institutes and the projects supported by EURAMET in recent years.

Figure 2. Spectral distribution of indoor light sources and spectral responsivities of indoor PV devices

Measurement of Indoor PV devices

The methods developed for the measurements of outdoor PV devices are well defined in the series of IEC 60904 standards. The content of these standards can briefly be explained as:

Measurement of photovoltaic current-voltage characteristics (IEC 60904-1),
Requirements for reference solar devices (IEC 60904-2),
Reference spectral irradiance data (IEC 60904-3),
Procedures for establishing calibration traceability (IEC 60904-4),
Determination of the equivalent cell temperature (IEC 60904-5),
Computation of the spectral mismatch correction (IEC 60904-7),
Measurements of responsivity (IEC 60904-8),
Classifications of solar simulators (IEC 60904-9),
Measurements of non-linearity (IEC 60904-10).

Moreover, there is also another series of IEC 61215-1-(1-4) standards have been used prior to the I-V measurements in order to eliminate the electrical instabilities and therefore to improve the measurement accuracy. Besides these, the standard test conditions (AM1.5, temperature: 25 °C, irradiance 1000 W×m^-2) are defined in the IEC TS 61836 so as to perform all the measurements at the same conditions.

On the other hand, since the behavior of indoor PV devices varies greatly compared to outdoor PV devices, some of the above standards cannot be used for the measurements of these devices. Especially standards related to measurement of photovoltaic current-voltage characteristics (IEC 60904-1), requirements for reference solar devices (IEC 60904-2), reference spectral irradiance data (IEC 60904-3), procedures for establishing calibration traceability (IEC 60904-4) and classifications of solar simulators (IEC 60904-9) need to be modified or replaced with new standards according to the requirements of indoor PV devices.

As the indoor PV devices are mostly used in indoor applications where they will be illuminated with fluorescent, incandescent, LED, etc light sources with different spectral distributions. In the measurements, for the calibrations of lighting simulators the irradiances of the reference light sources can be adjusted to produce a known short-circuit current with a calibrated reference cell. If the spectral responsivities of indoor PV devices are different than the reference cell, then either a further adjustment of the intensity of light sources, or a spectral mismatch correction to the measured result is needed. Adjustment of the intensity of light sources is easier and contribute less uncertainty compared to spectral mismatch correction which involves several device parameters. For the adjustment of the intensity of light sources, for each indoor PV devices a reference cell having the same technology as the test cell is needed. The suggested standards which describes the reference cells for the indoor PV devices are IEC TS 62607-7-2, IEC TR 63228, SEMI-PV57-1214 and JIS C 8904 -2.

Another requirement for the modification or replacement of new standards for the indoor PV devices is that, since more than one illuminated light sources with different spectral distributions are used in measurements, a single standard test condition cannot be defined for the measurements of indoor PV devices. For the measurements of these devices new requirements for the lighting simulators and new conditions for the I-V measurements need to be determined. To specify indoor lighting simulator requirements; the SEMI PV80-0622 and IEC 62607-7-2 standards and to specify the I-V measurements of indoor PV devices the SEMI PV89-0622 and SEMI PV57-1214 standards have been developed.

Besides these, one of the most important differences compared to outdoor PV devices is the stabilization of electrical performance parameters. Contrary to outdoor PV devices, there is no existing standards describing the processes and no defined requirements for the electrical stabilization of indoor PV devices. To meet these needs, techniques that are recommended in IEC TS 62607-7-2, IEC TR 63228 and in the literature widely have been used.

For reliable measurements of indoor PV devices, prior to measurements, using the above specified standards and recommended techniques, the classifications of lighting simulators, optical characterizations and electrical stabilizations are recommended to be done. These measurements and characterizations are briefly explained in the related sections given below.

Optical Characterization of Lighting Simulators

The indoor PV devices as their names imply are in general used in indoor applications to convert the artificial light sources into electrical energy. Therefore, the simulators used for the measurements of electrical performance parameters of the indoor PV devices must have similar light sources. As the reference spectra for these kinds of light sources, the spectra defined by IEC 60904-3 and CIE 015: 2018; for the classification of lighting simulators in terms of spectral match/coincidence, spatial homogeneity and instability etc., the methods defined in the IEC TS 62607-7-2 and SEMI PV80 - 622 standards can be used. The accuracy of the measurements of electrical performance parameters of indoor PV devices varies depending on the class of the lighting simulator used. In order to accurately determine the electrical performance parameters of the indoor PV devices, the initial step is to make the optical characterizations of the lighting simulator in terms of match/coincidence, spatial non uniformity and instability of lights source.

Spectral Match/Coincidence Measurements

The measurement of spectral distribution of lighting simulator is need to be done so as to check how closely the spectral distribution of lighting simulator’s light sources spectrally matches or spectrally coincides with that of reference spectrum of light sources defined by CIE 015: 2018. The SEMI PV80-0622 standard separates the spectral irradiance measurements of indoor light sources into three band intervals as shown in Table 1. By comparing the ratio of lighting simulator spectra with the CIE 015: 2018 reference spectra, the spectral match for each band intervals can be determined.

Contrary to SEMI PV80-0622 standard, the IEC TS 62607-7-2 standard addresses the evaluation of spectral coincidence so as to determine how closely the spectral distribution of lighting simulator’s light sources matches with that of reference light sources. According to IEC TS 62607-7-2 standard, the spectral coincidence of the illumination sources can be calculated using the Eqn.1 (Figures 3-5).

[math]\displaystyle{ \text {indoor spectral coincidence = } \frac { \int E_{mes(\lambda)} S_{mes(\lambda)} d (\lambda) } { E_{ref(\lambda)} S_{mes(\lambda)} d (\lambda) } \text { (1)} }[/math]

where E_ref(λ) is the spectral irradiance of standard indoor light sources with standard indoor illuminance; S_mes(λ) is the relative spectral responsivity of the indoor cell.

Figure 3. Spectral Match/Coincidence measurements of LED simulator

Figure 4. Spectral Match/Coincidence measurements of warm white LED

Figure 5. Spectral Match/Coincidence measurements of fluorescent

Table 1. The spectral coincide of lighting simulator with respect to reference spectra

Band No	Bandwidth (nm)	Spectral Match 1			Spectral Match 2			Spectral Match 3
Band No	Bandwidth (nm)	AM1.5*	LS	R1	F**	LS	R2	L***	LS	R3
1	300-450	15.82			14.58			9.00
2	450-650	44.01			79.39			78.66
3	650-900	40.18			6.03			12.34
Classification
A+		A			B			C
0.99 < R₁,R₂,R₃ < 1.01		0.97 < R₁,R₂,R₃ < 1.03			0.90 < R₁,R₂,R₃ < 1.10			0.75 < R₁,R₂,R₃ < 1.25
* AM1.5 IEC 60904-3 low light 1000lx Fluorescent FL11 CIE015-2018 1000lx * LED B3 CIE015-2018 1000lx					R1: Ratio AM1.5/LS R2: Ratio F/LS R3: Ratio L**/LS

Illuminance Non-uniformity Measurements

The surface of the indoor PV devices and the illuminance non uniformity, affect the accuracy of the measurements of the electrical performance parameters. Since the surface of indoor PV devices have almost equivalent efficiencies, the accuracy of measurements depends strongly on the spatial distribution of the illuminance over the area of indoor PV devices. In order to measure the illuminance non-uniformity of the lighting simulator, the procedures described in the IEC TS 62607-7-2 and SEMI PV80-0622 standards can be used. According to these standards, the illuminance non-uniformity required to be done over the illuminated area and its value be evaluated using the equation as given in Eqn2.

[math]\displaystyle{ \text {Illuminance non uniformity = } \frac { (l_{max}-l_{min}) } { (l_{max}+l_{min}) } \times 100 \text { (2)} }[/math]

where I_max and I_min are the maximum and minimum values of currents generated within the area irradiated by the illumination source.

Comparing the evaluated values (Figure 6) with the reference values given in the Table 2, the lighting simulator’s classification can be done.

Figure 6. Illuminance non uniformity at different active areas

Table 2. Reference values for the classification of lighting simulators in terms of illuminance non-uniformity

Reference values for the non-uniformity	0.5 %	2 %	3 %	10 %
Classification of lighting simulator	A+	A	B	C

Temporal Instabilities of Illuminance

The instabilities of the lighting simulator’s illuminances can be measured according to procedures described in the IEC TS 62607-7-2, SEMI PV80-0622 and IEC 60904-9 standards. The temporal instability is related to the change of measured illuminance data sets during the time of data acquisition. There are two types of instabilities; short term instability (STI) and long term instability (LTI). The STI relates to the data sampling time of a data set (illuminance, current, voltage) during an I-V measurement and it was determined from the worst case data sets on the I-V curve. On the other hand LTI related to the time period for taking the entire I-V curve (Figures 7-9). Both STI and LTI can be evaluated using the maximum and minimum illuminance values and the Eqn3. Then the classification can be done according to the values given in Table 3.

[math]\displaystyle{ \text {Illuminance temporal instability = } \frac { (l_{max}-l_{min}) } { (l_{max}+l_{min}) } \times 100 \text { (3)} }[/math]

Figure 7. Instability of the AM1.5 lighting simulator

Figure 8. Instability of the F lighting simulator

Figure 9. Instability of the LEDB lighting simulator

Table 3. Reference values for the classification of lighting simulator in terms of temporal instability.

Reference values for the temporal instability	0.5 %	1.0 %	3.0 %	10.0 %
Classification of lighting simulator	A+	A	B	C

Optical characterizations of indoor PV devices

The optical characterizations of indoor PV devices cover the measurements and evaluations of linearity, temperature dependency, angular responsitivity, flickering etc. parameters which have effect on the electrical performance parameters.

The measurements of non-linearity of indoor PV devices

The PV devices at indoor applications mostly are subjected to artificial light sources like florescent, incandescent, LED, etc. with various illuminance levels varying from few lx to about 2000 lx (few irradiance to 10 W∙m^-2 irradiance). These indoor PV devices are in general calibrated at a specific irradiance value and their performances within the mentioned irradiance range can be predicted via knowledge of linearity. There are many different methods exists for the measurements and determinations of linearity of PV devices. Among them, the fastest and simplest one will be the I-V measurements of indoor PV devices (DSSC, PSC and OPV) by varying the incident irradiance. Then from the I-V curves, the variation of the current and voltage as a function of incident irradiance can be derived and any linearity or non-linearity can be observed

The non-linearity measurement results of PSC device

Current – voltage (I-V) measurement results of PSC as a function of irradiance (W×m^-2) or lux (lx) values is shown in Figure 10 a. The current (A) – lux (lx) and voltage (V) – lux (lx) relations derived from these measurements are shown in Figure 10 b -10 c.

Figure 10. (a) Current – Voltage measurements of PSC as a function of irradiance, (b) Current generated from PSC as a function of irradiance and (c) Voltage generated from PSC as a function of irradiance

The non-linearity measurement results of DSSC device

Current – voltage (I-V) measurement results of DSSC as a function of irradiance (W×m^-2) or lux (lx) values is shown in Figure 11 a. The current – lux and voltage – lux derived from these measurements are shown in Figures 11 b -11 c

Figure 11 (a) Current – Voltage measurements of DSSC as a function of irradiance, (b) Current generated from DSSC as a function of irradiance and (c) Voltage generated from DSSC as a function of irradiance

The non-linearity measurement results of OPV device

Current – voltage (I-V) measurement results of OPV as a function of irradiance (W×m^-2) or lux (lx) values is shown in Figure 12 a. The current – lux and voltage– lux relations derived from these measurements are shown in Figures 12 b -11 c.

Figure 12. (a) Current – Voltage measurements of OPV as a function of irradiance, (b) Current generated from OPV as a function of irradiance and (c) Voltage generated from OPV as a function of irradiance

The measurements of temperature coefficients of indoor PV devices

The electrical performance parameters of indoor PV devices can be determined under the light sources (fluorescent, incandescent, LED) having different spectral distributions with illuminance levels varying from few lx up to 2000 lx (few irradiance to 10 W∙m^-2) and at a fixed temperature. Hence, there are more than one measurement conditions presents for the indoor PV devices. Moreover, depending on the seasons, indoor climatic conditions, etc., the indoor PV devices may be exposed to temperatures, typically from 10 ^ºC to 40 ^ºC which are different than the measurement temperature. This temperature difference can results in variations in the electrical performance parameters. Therefore, the measurements and determination of the effects of temperature variation on the electrical parameters of indoor PV devices is necessary in order to accurately make their performance analysis. For the temperature dependent measurements, the temperatures of indoor PV devices should be adjusted by a suitable method (i.e. thermal cabinet, thermoelectric, etc.). At each set temperatures, by illuminating indoor PV devices with any of indoor light sources (fluorescent, incandescent, LED) the temperature dependent electrical performance parameters can be realized. Applying one of the method suggested in IEC 61853 standard, the temperature coefficients for the short circuit current α(%ºC^-1), the open circuit voltage β(%ºC^-1) and the maximum power d(%ºC^-1) can be obtained.

The temperature dependent measurement results of PSC device

Current – voltage (I-V) and power – voltage (P-V) measurement results of PSC as a function of temperature values are shown in Figures 13. The current– temperature, voltage – temperature and power – temperature relations derived from these measurements are shown in Figures 14a – 14c.

Figure 13. Temperature dependent I-V and P -V measurements of PSC

Figure 14. (a) Current generated from PSC as a function of temperature, (b) Voltage generated from PSC as a function of temperature and (c) Power generated from PSC as a function of temperature

The temperature dependent measurement results of DSSC device

Current – voltage (I-V) and power – voltage (P-V) measurement results of DSSC as a function of temperature values are shown in Figures 15. The current – temperature, voltage – temperature and power – temperature relations derived from these measurements are shown in Figures 16a - 16c.

Figure 15. Temperature dependent I-V and P -V measurements of DSSC

Figure 16. (a) Current generated from DSSC as a function of temperature, (b) Voltage generated from DSSC as a function of temperature and (c) Power generated from DSSC as a function of temperature

The temperature dependent measurement results of OPV device

Current – voltage (I-V) and power – voltage (P-V) measurement results of OPV as a function of temperature values are shown in Figures 17. The current – temperature, voltage – temperature and power – temperature relations derived from these measurements are shown in Figures 18a -18c.

Figure 17. Temperature dependent I-V and P -V measurements of OPV

Figure 18. (a) Current generated from OPV as a function of temperature, (b) Voltage generated from OPV as a function of temperature and (c) Power generated from OPV as a function of temperature

The measurements of angular responsivity of indoor PV devices

Current – voltage (I-V) measurements of indoor PV devices depending on the irradiance level can be realized using a suitable method described in IEC60904-1, SEMI PV89-0622 and SEMI PV57-1214 standards. All these standards define the measurements of indoor PV devices placed directly under light sources. However, in reality at various indoor applications, these devices may not be located directly under the light sources, they may receive light from various angles. Therefore, it is obvious that their performance at various angles will differ a lot compared to the performances obtained under normal incident light. In order to determine the indoor PV devices performances corresponding to actual conditions, it is very important to measure their electrical performances parameters as a function of incident angle using the method described in the SEMI PV69-0622 and IEC 61853-2 standards.

The angular dependent measurement results of PSC device

Current – voltage (I-V) measurement results of PSC as a function of rotation angle are shown in Figures 19. The current and voltage generated as a function of rotation angle is shown in Figures 20.

Figure 19. I-V measurements of PSC between -85° and +85°

Figure 20. Generated current and voltage from PSC between -85° and +85°

The angular dependent measurement results of DSSC device

Current – voltage (I-V) measurement results of DSSC as a function of rotation angle are shown in Figures 21. The current and voltage generated as a function of rotation angle is shown in Figures 22.

Figure 21. I-V measurements of DSSC between -85° and +85°

Figure 22. Generated current and voltage from DSSC between -85° and +85°

The angular dependent measurement results of OPV device

Current – voltage (I-V) measurement results of OPV as a function of rotation angle are shown in Figures 23. The current and voltage generated as a function of rotation angle is shown in Figures 24.

Figure 23. I-V measurements of OPV between -85° and +85°

Figure 24. Generated current and voltage from OPV between -85° and +85°

The measurements of spectral responsivity of indoor PV devices

The electrical performance parameters (current, voltage, power) of indoor PV devices can be measured using the lighting simulators that meet the SEMI PV80-0622 standard requirements. The lighting simulators have any of fluorescent, incandescent, LED light sources with different spectral distributions. Since the sensitive wavelength regions of indoor PV devices may not coincide with all the spectral distributions of lighting simulator’s light sources, it is necessary to apply some spectral corrections so as to accurately determine their performances. Therefore, in order to evaluate spectral mismatch and apply correction to the irradiances of different light sources, the spectral responsivities of indoor PV devices are needed. There are different methods for the measurements of spectral responsivities of PV devices. For the measurements of spectral responsivity of outdoor PV devices in general the method defined in the IEC 60904-8 standard is used. The same method can also be applied to indoor PV devices provided certain precautions like; device nonlinearity, response time non uniformity and stability are taken into account. Besides IEC 60904-8, the method described in the SEMI PV69-0622 standard can also be used. According to these standards the spectral responsivity of indoor PV devices can be obtained by irradiating them by means of a narrow-band light source and measuring their short circuit currents (Figure 25).

Figure 25. Spectral responsivity of indoor PV devices

Effects of Modulated Light Sources

Outdoor PV devices are used outdoors under sunlight. Since sunlight radiates continuously over time, light falls on outdoor PV devices has continuous radiation over time. However, indoor PV devices are used under LED, fluorescent, incandescent like indoor light sources. Recently, indoor lighting technology has undergone a significant shift from traditional incandescent and fluorescent lamps towards solid-state lighting devices featuring light-emitting diodes. LEDs offer not only high power efficiency but also rapid response capabilities, allowing precise control of illumination levels through pulse-width modulation (PWM) of the current source. Despite the advantages of PWM in achieving desired illumination levels, it introduces a challenge related to the inherent characteristics of LEDs. The transition from off to on states of an LED under PWM driving results in an instantaneous change in light intensity, leading to perceptible lighting flicker. Therefore, modulated light falls on indoor PV devices. The modulation frequency falling on Indoor PV devices can vary between a few Hz and kHz depending on the light source. For this reason, in order to accurately determine the performance of indoor PV devices, it is necessary to measure the I-V measurements of these devices between a few Hz and kHz and to examine the effects of the modulation frequency (Figures 26 - 28).

Figure 26. Effects of modulation frequency on I-V measurements of indoor PSC

Figure 27. Effects of modulation frequency on I-V measurements of indoor DSSC

Figure 28. Effects of modulation frequency on I-V measurements of indoor OPV

Electrical Stabilization of Indoor PV Devices

For the reliable measurements of PV devices, one of the important parameter is the electrical stabilization of their electrical performance parameters. For the outdoor PV devices, there are well defined series of IEC 61215-1-(1-4) standards which describe the stabilization procedures and the conditions to evaluate the stabilization levels. On the other hand, for the indoor PV devices there is no existing standards describing the stabilization procedures and the conditions for the evaluation of their stabilization levels. Therefore, prior to current- voltage (I-V) measurements of indoor PV devices in order to eliminate their electrical instabilities the stabilization techniques recommended in IEC TS 62607-7-2, IEC TR 63228 and in the literature are widely used. These stabilization techniques briefly are as follows:

1. Long terms stabilization, which is done by light soaking systems. In this stabilization process, the indoor PV devices are kept under light sources and their electrical performances (current) will be observed until the stable condition is reached (Figure 29).

Figure 29. Long term stabilizations of PSC, DSSC and OPV

2. Pre-conditioning, which is used to hold the indoor PV devices under a certain set of conditions, again irradiance, temperature and voltage bias, for some period immediately prior to making a current-voltage (I-V) measurements. The aim is to create short-term stability in the device, so that a subsequent I-V measurement reflects or approximates the steady-state device performance in a relatively rapid voltage sweeps (Figure 30).

Figure 30. Preconditioning of PSC, DSSC and OPV

3. Steady-state process which is required to create a condition, on which the voltage sweep rate kept slow enough to allow each current measurement to stabilize. For this, initially perform the measurements by varying voltage step lengths until the forward and reverse I-V curves match well. After determining the voltage step length, in the next stage with perform the measurements by varying the time length and observe until the forward and reverse I-V curves match well again. In this way both voltage step length and time required to make measurement at this voltage step length can be obtained for each indoor PV devices. In the Figure 41 determination of voltage step length and time required for this step length for PS, DSSC and OPV indoor PV devices are shown.

Figure 31. Voltage step length and time required for this step length for PS indoor PV device

I-V Measurements of Indoor PV devices

Current – voltage (I-V) measurements of the indoor PV devices depends on both the lighting simulators and measurement conditions. The lighting simulators should meet the SEMI PV80-0622 and IEC 60904-9 standards requirements and their calibration should be done in accordance with IEC 60904-2 standard. The reference PV device used in the calibration shall be linear in short-circuit current as defined in IEC 60904-10 over the illuminance range of interest.

The indoor PV devices depending on the technology they made, show different behaviors from each other and hence their measurement conditions can be quite different. I-V measurements of indoor PV devices, which have fast current response to an applied voltage under illumination can be done according to the standard procedure described in IEC 60904-1 standard. However, most of the indoor PV devices have slow current response to an applied voltage under illumination and also their I-V measurements can be influenced by the voltage sweep rate and the sweep direction. For these kinds of indoor PV devices, to avoid measurement errors arising from the device response time, the appropriate voltage step length and voltage swept time should be selected.

For the measurements of these devices, the measurement techniques that are recommended in IEC TS 62607-7-2, SEMI-PV57-1214, SEMI PV89-0622 and IEC TR 63228 standards have been used. The main stages of the compiled version of the measurement methods of these standards are briefly as follows:

Lighting simulator should be characterized and calibrated according to IEC 60904-9, SEMI PV80-0622 and IEC 60904-2 standards.
Irradiance/illuminance of lighting simulators should be adjust the using a calibrated reference cell (S. Winter et al.,2021)
Indoor PV device should be stabilized according to TS 62607-7-2 and IEC TR 63228 with following steps :
- Preconditioning should be done to limit degradation and create short-term stability
- Suitable voltage step length and voltage swept time should be determined such that to allow current be stabilized at each voltage level.
- Stability should be monitored and the steady-state conditions of I_sc and V_oc should be determined.
- The steady-state current should be measured at voltages near P_max
I-V measurements should be done with forward and reverse scans at various scan rates (varying voltage sweep times)
P_max should be evaluated for both forward and reverse scans to check their consistencies.
The metric used to check the consistency of these measurements is the agreement between P_max values from the forward and reverse I-V measurements, given as in Eqn.4.

[math]\displaystyle{ \mid ( P_{max}^{f} P_{max}^{r} ) \mid / P_{max}^{f} P_{max}^{r} \lt x \text { (4)} }[/math]

where x is taken as a value of around 2 %.

If the consistency condition is not reached, then the stabilization procedures in the third stage should be revised and changed until consistency is achieved.

By applying these methods to the PS, DSSC and OPV indoor devices, the I-V measurement results of indoor PV devices can be realized as shown in the Figure 32 - 34.

Figure 32. I-V measurements of PSC under AM 1.5, LED B and illuminant A light.

Figure 33. I-V measurements of DSSC under AM 1.5, LED B and illuminant A light.

Figure 34. I-V measurements of OPV AM 1.5, LED B and illuminant A light

References

IEC 60904-1:2020, Photovoltaic devices - Part 1: Measurement of photovoltaic current-voltage characteristics.
IEC 60904-2:2007, Photovoltaic devices - Part 2: Requirements for reference solar devices.
IEC 60904-3:2019, Photovoltaic devices - Part 3: Measurement principles for terrestrial photovoltaic (PV) solar devices with reference spectral irradiance data.
IEC 60904-4:2019, Photovoltaic devices - Part 4: Reference solar devices - Procedures for establishing calibration traceability.
IEC 60904-5:2011,Photovoltaic devices - Part 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage method
IEC 60904-7:2019, Photovoltaic devices - Part 7: Computation of the spectral mismatch correction for measurements of photovoltaic devices.
IEC 60904-8:2017, Photovoltaic devices - Part 8-1: Measurement of spectral responsivity of multi-junction photovoltaic (PV) devices.
IEC 60904-9:2020, Photovoltaic devices - Part 9: Classification of solar simulator characteristics.
IEC 60904-10:2020, Photovoltaic devices - Part 10: Methods of linear dependence and linearity measurements.
IEC 61215-1-1:2021, Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-1: Special requirements for testing of crystalline silicon photovoltaic (PV) modules.
IEC 61215-1-2:2021, Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-2: Special requirements for testing of thin film Cadmium Telluride (CdTe) based photovoltaic (PV) modules.
IEC 61215-1-3:2021, Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-3: Special requirements for testing of thin film amorphous silicon based photovoltaic (PV) modules.
IEC 61215-1-4:2021,Terrestrial photovoltaic (PV) modules - Design qualification and type approval - Part 1-4: Special requirements for testing of thin film Cu(In,GA)(S,Se)2 based photovoltaic (PV) modules ()
IEC TR 63228:2019, Measurement protocols for photovoltaic devices based on organic, dye-sensitized or perovskite materials.
SEMI PV57-1214, Test Method For Current-Voltage (I-V) Performance Measurement of Organic Photovoltaic (OPV) and Dye-Sensitized Solar Cell (DSSC) and Perovskite Solar Cell (PSC)
SEMI PV69-0622, Test method for spectrum response (SR) measurement of organic photovoltaic (OPV) and dye-sensitized solar cell (DSSC) and perovskite solar cell(PSC)
SEMI PV80-622, Specification of Indoor Lighting Simulator Requirements for Emerging Photovoltaic and Perovskite Solar Cell (PSC)
SEMI PV89-622, Test Method of Current-Voltage (I-V) Measurement in Indoor Lighting for Dye-Sensitized Solar Cell and Organic Photovoltaic and Perovskite Solar Cell (PSC)
JIS C 8904 -2, Photovoltaic devices – Part 2: Requirements for reference solar devices, (original in Japanese).: Japanese Standards Association, 2011
IEC 62607-7-2, Nanomanufacturing - Key Control Characteristics - Part 7-2: Nano-enabled photovoltaics - Device evaluation method for indoor light
IEC 61853-2:2016,Photovoltaic (PV) module performance testing and energy rating - Part 2: Spectral responsivity, incidence angle and module operating temperature measurements
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