Solar cell testing system

At present, the laboratory efficiency of many perovskite cells has reached the same level as or even exceeded that of crystalline silicon. In terms of efficiency, perovskite cells can be commercially applied and have lower preparation costs than traditional crystalline silicon cells. However, the obstacle to the commercialization of perovskite cells is their long-term stability. Currently, the most direct way to solve this problem in the industry is to modify the perovskite material itself to improve its intrinsic stability. Another feasible approach is to isolate external unstable factors through processes and engineering methods, such as isolating environmental factors such as water and heat, in order to reduce or even avoid the impact of external unstable factors on materials and devices.

At present, there is no internationally unified standard for stability testing of perovskite solar cells. The common practice in the industry is to place the cell under 1-second standard light irradiation and conduct continuous maximum power point tracking (MPPT) for photo aging testing. The regular testing time is 1000 hours.

This system is a powerful and comprehensive multi-channel solar cell and module stability testing system tailored for researchers of perovskite solar cells. It uses 3A-levelLED solar simulator or white LED can be used as an aging light source to control the temperature of the battery and the environmental atmosphere in which the battery is located (N2, dry air, constant temperature and humidity, etc.) through various methods. It can simultaneously conduct long-term stability performance tests on multiple groups of batteries. In addition to the traditional MPPT mode, constant voltage (such as open circuit voltage) and constant current aging (such as short circuit current) modes are also added to increase the flexibility of stability research, and powerful data analysis software is integrated to view and compare various performance indicators of different samples in real time.

1Solar cell testing systemSystem Composition

1.1 Hardware System

1.1.1 Aging light source

This system can be optionally equipped with 3A-levelLED solar simulator and white LED monochromatic light source, the following introduces the two types of light sources respectively

●3A-levelLED solar simulator

The BG-LED-AAA series LED solar simulator is an ideal solar light source for scientific research, which is an upgraded product of the current xenon lamp solar simulator. Its excellent characteristics are more suitable for research on solar cells, semiconductor materials, and biological sciences

Product Features

● Complies with the A+requirements of IEC 60904-9, JIS 8904-9, and ASTM E927-10 regarding spectral matching A+, radiation spatial uniformity A, and temporal instability.

Using imported high-power LED chips and various wavelengths of LEDs for spectral fitting, the simulation of sunlight has been achieved

The lifespan of the light source is over 10000 hours, eliminating the need for regular replacement of expensive and dangerous light bulbs.

● Independent spectral control, within the spectral range of 350nm to 1150nm, divided into 6 spectral segments according to IEC 60904-9 standard, each spectral segment can be independently adjusted and controlled. Users can customize different spectra to meet different testing needs.

● Wide flash time control, capable of achieving a minimum continuous flash of 100ms until constant brightness

● Optional light intensity feedback system, real-time light intensity for rapid calibration

7-inch LCD touch screen control, graphical interface operation, quick and convenient operation.

Supports 5 preset flashing schemes and seamless switching, suitable for different testing needs.

Equipped with CAN bus, RS232 and RS485 interfaces, it can be interconnected with external testing equipment to achieve remote control and collaboration.

Multi channel solar cell stability testing systemTechnical Specifications

spectrogram

LED white light source

Light source characteristics

● Large area

① Lamp board area: 300 × 200mm ², effective illumination area: 270 × 180mm ²;

② Lamp board area: 360 × 360mm ², effective illumination area: 350 × 350mm ²;

Ultra large illumination area LED bead array light board, supporting multiple small batteries and small modules for simultaneous illumination testing.

● Long lifespan

Stability: 10000 hours;

This component uses imported lamp beads with high stability and long service life, customized high heat capacity aluminum alloy heat sinks, and two heat dissipation methods: infinite speed regulation matrix air cooling and compression refrigeration cycle water cooling, to ensure the service life of the light source under continuous illumination. On the premise of maintaining the intensity of the light source, it greatly delays the decline of the light source intensity.

● Material selection

Imported LED beads; High heat capacity 7075 aluminum alloy oxidation baking paint lamp body/high-strength 304 stainless steel frosted baking paint lamp body.

● Adjustable light intensity:

0.1-4 Sun equivalent light intensity adjustable; The adjustable power range of 20W-900W is about 180W, which enables the perovskite solar cell to generate a current output under a solar simulator.

● Wavelength range

Single wavelength 450nm

● Customizable:

The light intensity accepts non-standard customization, and the equivalent light intensity of the shipped light board can reach up to 7sun; The lamp board area accepts non-standard customization, and the maximum shipped lamp board area can reach 1000mm × 600mm, which can be even larger.

● Safe and reliable:

Leakage protection&overvoltage/overcurrent protection system.

Spectral diagram of light source

Comparison of Two Light Source Solutions

1.1.2 Testing System

This system can be configured with an independent single channel measurement system and a single channel polling measurement system, which will be introduced separately below

● Multi channel parallel testing system

Adopting low-power programmable DC electronic load cards, it has the characteristics of high precision, high reliability, full functionality (constant current, constant voltage, constant power, constant resistance), and easy integration. Equipped with OCP/OVP/OPP/OTP multi protection and high-speed LAN interface, it can replace low-power single electronic loads in most integrated applications and significantly save costs for users, especially suitable for applications in universities and research institutes.

Product Features:

Power range: 20W/25W/50W

Voltage range: 0~20V/0~60V/0~100V

● Single machine 10/19 channels, isolated between channels

● OCP/OVP/OPP/OTP multiple protection

● Current range: 0~1A/0~5A/0~10A

● Working modes: CC, CV, CP, CR, CCD

● Supports LAN communication and dual LAN interfaces

● Support functions such as simulating short circuits, carrying/unloading locks, etc

Specification Table for Solar Cell Testing System Parameters

Single channel polling measurement system

This system adopts the Jishili 24XX series source table+self-developed source table channel extender, which can expand a single channel Jishili 24XX series source table into 24 channels to achieve multi-channel polling measurement

24XX series source table

Source Table Channel Switcher

Comparison of two measurement schemes

1.1.3 Test fixtures

Our company can customize N2 sample chambers, which are sealed with sealing rings to prevent leakage. Electrical connections can be achieved by introducing wires into the chamber through airtight multi-core power cords. This method is easier to operate.

● Integrated multi-channel nitrogen sealed temperature control fixture

Nitrogen sealed semiconductor temperature control fixture

Power supply: DC12V

Power consumption: 150W

● Temperature control range: Cooling limit: 10 ℃ below room temperature, Heating limit: 85 ℃

Temperature stability: ± 0.3

Nitrogen control pressure: ＜ 2kpa

The nitrogen sealing fixture can be customized according to the user's time, battery size, and electrode distribution

● Multi channel split type nitrogen seal temperature control fixture

Temperature control in conventional environment: It is necessary to test the controllable packaged battery by passing it through a water-cooled plate and a heating plate for temperature control. The temperature control water-cooled test base is 5 ℃ -35 ℃, with an accuracy of ± 1 ℃; Temperature controlled heating test base RT-120 ℃, accuracy ± 0.5 ℃. Our company can customize water-cooled and heating plates of any size

Nitrogen sealing fixture body

Temperature controlled heating table

Temperature controlled cooling table

1.2 Software System

In addition to supporting MPPT testing mode, this software also adds constant voltage (such as open circuit voltage) and constant current aging (such as short-circuit current) measurement modes

● IV testing

This software supports setting the starting voltage, ending voltage, scanning step size, and positive and negative IV scanning functions

IV curve

pressure-volumecurve

MPPT tracking mode

P-T curve in MPPT scanning mode

Using perturbation algorithm, the maximum power point position of the solar cell is continuously feedback corrected during the testing process, so that the battery can remain in the maximum power discharge state for a long time. The output power is monitored in real time during the discharge process. The maximum power value and P-t curve are collected and recorded by setting the testing duration and scanning interval time. The time display unit can be selected as specific date/day/hour/minute. During MPPT tracking, regularly scan the positive and negative scan IV curves (e.g. every 10 hours) during the total testing time (e.g. 1000 hours), and record the changes in four key performance indicators of the battery, including VOC, ISC, FF, and PCE, over time (100 data points within 1000 hours). Note that it is meaningful to provide the P-t and PCE-t (positive and negative scans) of the battery at this point. The data points for P-t may reach hundreds of thousands (such as recording a P point every 10 seconds, which would result in a total of 360000 data points within 1000 hours), far more than the data points for PCE-t. In fact, due to the presence of hysteresis effect, PCE-t has certain errors in both forward and reverse scan results, while P-t more accurately reflects the true power changes of perovskite solar cells.

● Constant voltage mode

P-T curve in constant voltage measurement mode

Like MPPT, it is necessary to obtain the changes in four key performance indicators over time through regular IV scans, but the battery is in constant voltage mode between regular IV scans. By using a constant voltage mode through the source table, the load of the source table is controlled to be at a fixed V or dynamic Vmpp, and the changes in monitoring devices I-t and P-t are monitored. At this point, P-t may not be the maximum power, but it still has certain physical significance and research value, especially for the movement of perovskite ions under bias voltage. V can be set as any constant value between 0 and VOC, or as Vmpp obtained from the previous IV test's forward or reverse scan. If set to a constant V value, the battery remains constant under the constant bias voltage V throughout the entire testing time range. If set as the Vmpp for the previous IV test, dynamic adjustments will be made through IV scans within a fixed period, but between two IV tests, it will be fixed at Vmpp. Note that the Vmpp for forward and reverse scans is different. Controlled at dynamic Vmpp, this mode also has similarities to MPPT, but the subtle difference from MPPT is that Vmpp remains constant between two IV tests, while in MPPT mode, V changes in real-time at any time. Many literature adopt the initial Vmpp, which remains constant for 1000 hours. Compared with the variation Vmpp in this test, the deviation from the true maximum power is larger, and the variation Vmpp in this test has a slight deviation from the true maximum power compared to the previous MPPT.

● Constant current mode

P-T curve in constant current measurement mode

The constant current mode, like MPPT, requires periodic IV scans to obtain the changes in four key performance indicators over time. However, the battery remains in constant current mode between periodic IV scans. By adopting a constant current mode through the source table, the load of the source table is controlled to be at a fixed I or dynamic I (mpp), and the changes in the monitoring devices V-t and P-t are monitored. Among them, I can be set as any constant value between 0-I (SC), or it can be set as I (mpp) obtained from the previous IV test positive or negative scan. If set to a constant I value, the battery remains constant under the action of a constant current I throughout the entire testing time range. If set to the I (mpp) of the previous IV test, dynamic adjustments will be made through IV scans within a fixed period, but between two IV tests, it will be fixed at I (mpp). Note that the forward scan and reverse scan I (mpp) are different. Controlling in dynamic I (mpp) mode is similar to controlling in dynamic V (mpp) mode, and the data obtained has specific scientific value.

2、 Customer Case

Case 1: A university in Shanghai

LED white light source | Parallel measurement scheme | Split type nitrogen sealed temperature control fixture