Need for standardization of bifacial measurements

1. Need for standardization of
IV-measurements of
bifacial cells and modules
Dr. Axel Metz
Managing Director
h.a.l.m. elektronik GmbH, Frankfurt, Germany
bifi PV workshop, 2014
Chambery, France, May 26th & 27th 2014

2. Company profile
 30 years of measurement experience in industrial environment
 Headquarter in Frankfurt, Germany + local office in Suzhou, China
 Expertise in various industrial areas
 Active in PV industry since more than 15 years
 More than 900 systems sold worldwide, equivalent > 30 GWp/a
 References: Yingli, Trina, Solarworld, FhG ISE, PTB, TÜV, VDE, ...
www.halm.de © h.a.l.m. elektronik gmbh

3. Product portfolio
IV measurement and sun simulating systems for:
 Solar cells (production and research)
- High speed inline testers up to 5100 cells/hour
- EL and IR imaging
- Highly flexible lab systems
 PV-Modules (production and research)
- High throughput sun simulators up to 240 modules/hour
- Optional EL integration
- Lab system with high precision temperature control unit
 PV-Systems
- High precision portable outdoor measurement system
www.halm.de © h.a.l.m. elektronik gmbh

4. Why do we need standards?
 To make things comparable world wide
 To ensure quality and reduce risks
 To save money at all levels of the value chain
 As manufacturer
 As equipment or material supplier
 As testing institute
 As system integrator
 As end customer
© h.a.l.m. elektronik gmbh

5. Outline
 Applications for bifacial solar cells and modules
 Important design parameters of bifacial systems
 Requirements for reproducible IV-measurement of bifacial PV devices
 Considerations for different levels of the value chain
 Conclusions
© h.a.l.m. elektronik gmbh

6. Applications for bifacial cells and modules
Bifacial solar cells
 Assembly in modules with opaque back cover
 Monofacial module
 back side performance
almost independent
from mounting conditions
 Assembly in modules with transparent back cover
 Bifacial module
 back side performance
strongly dependent
on mounting conditions
© h.a.l.m. elektronik gmbh

7. Applications for bifacial cells and modules
Bifacial PV modules
 Sound barrier
 Mounted vertically (preferrably east/west orientation)
 Roof mounted
 on a flat roof
 on a tilted roof
 Solar park
 ground mounted at fixed angle
 mounted on tracking system
 Building integrated
 facade integrated
 as shadowing element
 roof integrated
© h.a.l.m. elektronik gmbh

8. Important parameters for bifacial systems
Relevant for system performance
 Module position
 tilt angle
 module direction
 module orientation (portrait or landscape)
 Albedo
 System geometry
 distance from reflector
 geometry of opaque, transparent and open area
© h.a.l.m. elektronik gmbh

9. Requirements for reproducible measurements
Front side
 STC: 1000 W/m2, AM1.5G, 25°C
Back side
 Intensity
 Spectrum
 Non uniformity
 Temporal stability
Timing
 Simultaneous front and back illumination or
 Sequential front and back illumination
© h.a.l.m. elektronik gmbh

10. Considerations for different levels of the value chain
Cell
 classification for optimum matching in module (inline 100%)
 cell power at bifacial STC (inline, 100%)
Module
 module power at bifacial STC (inline, 100%)
 energy rating (offline, per module type)
System
 energy yield modelling for specific applications, mounting
and climate conditions
© h.a.l.m. elektronik gmbh

11. Conclusions
 Short term need for standards for IV-measurement
of bifacial devices
 To reduce complexity, two standards are required:
 bifacial STC for 100% inline inspection
 offline energy rating of bifacial modules
 New standards for bifacial devices should be:
 based on existing standards
 simple and pragmatic
© h.a.l.m. elektronik gmbh

12. Proposal for standardized IV measurement of bifacial devices
Front side
 STC: 1000 W/m2, AM1.5G, 25°C
Back side
 Intensity: 200 W/m2
 Spectrum: AM1.5G
 Non uniformity: 2%
Timing
 Simultaneous front and back illumination
Optional
 additional illumination conditions
 front 1sun / back 0 sun and/or
 front 1 sun / back 1 sun and/or
 front 0 sun / back 1 sun
© h.a.l.m. elektronik gmbh