1 N. Ferretti, Investorentag PI-Berlin, 30.10.20131 N. Ferretti, BifiPV Workshop, 26.05.2014
Nicoletta Ferretti, Giulia Mancini, Juliane Berghold, Paul Grunow (PI-Berlin)[email protected], Tel.: +49 30 8145264-119
PI Photovoltaik-Institut Berlin AG, Wrangelstraße 100, 10997 Berlin
Power measurements of bifacial
modules
2 N. Ferretti, Investorentag PI-Berlin, 30.10.20132 N. Ferretti, BifiPV Workshop, 26.05.2014
Content
• The output power of bifacial modules in the field depends on the albedo Difficulty for energy yield predictions.
• STC measurement of bifacial module outdoor and in the lab taking albedo impact into account
Measurements at different and defined backgrounds.
• Outdoor power logging of a bifacial and a standard module as reference.
• Comparison of specific energy yields with respect to Pmax of bifacial module.
• Conclusions and outlook.
3 N. Ferretti, Investorentag PI-Berlin, 30.10.20133 N. Ferretti, BifiPV Workshop, 26.05.2014
Bifacial modules
The output power depends on the albedo (reflection ratio from the ground) Difficulty for energy yield predictions.
No standards for I-V curve measurement at STC of bifacial modulesBifacial modules can not be compared and economically evaluated.
4 N. Ferretti, Investorentag PI-Berlin, 30.10.20134 N. Ferretti, BifiPV Workshop, 26.05.2014
Field Installation
Field installation in Germany, Albedo 64%, Sanyo HIT-DNKHE1: 70% back-to-front efficiency, Sanyo data sheet 04/2010
Sanyo bifacial: 24% more energy yield compared to own standard module.
Need to define Pmax evaluation for energy yield prediction and for economical
evaluation of the bifacial modules.
5 N. Ferretti, Investorentag PI-Berlin, 30.10.20135 N. Ferretti, BifiPV Workshop, 26.05.2014
Outdoor STC: Pmax vs. background
Pmax measured at the flasher by covering the not measured side by a black foil:Pmax Front=236 W
Pmax Back= 189 W
Bifaciality=79%
Pmax is changing depending on the background
Height=55 cmAngle= 30°Area background: 7m x 5m
6 N. Ferretti, Investorentag PI-Berlin, 30.10.20136 N. Ferretti, BifiPV Workshop, 26.05.2014
Indoor STC
Background for bifacial modules(2.6 m x 3.4 m )
Background Albedo Ground
Grey 25% GrassSilver 33% SandWhite 58% Snow
Albedo measured with a cell at the flasher
[Pasan manual SS3b] No-reflecting walls
Bifacial module
7 N. Ferretti, Investorentag PI-Berlin, 30.10.20137 N. Ferretti, BifiPV Workshop, 26.05.2014
STC comparison Outdoor/flasher
BackgroundPmax Outdoor
(W)Pmax Flasher
(W)Deviation
(%)
WHITE 282.9 285.1 -0.8
SILBER 274.3 271.3 1.1
GREY 265.0 268.6 -1.3
Reference 251.6 251.9 -0.1
Repeatability bifacial outdoor=0.9%Repeatability Reference outdoor=0.5%Uncertainty Pmax Flasher =2.9%
A standard module is also tested both outdoor and at the flasher as reference.
8 N. Ferretti, Investorentag PI-Berlin, 30.10.20138 N. Ferretti, BifiPV Workshop, 26.05.2014
Bifacial modules measurements at flasher
Producer Pmax front (W)
Bifaciality (%)
a1 287.6 54.6a2 285.1 53.0a3 284.2 52.7b1 255.4 91.6b2 255.8 91.4b3 255.8 91.5b4 255.0 91.6
c1 246.9 76.5
c2 247.2 76.9
c3 79.90 79.1
The Pmax deviation measured with defined albedo (white/grey background) is not directly related to the evaluated bifaciality.
Single side measurents covering the not illuminated side with a black foil.
Pmax measurements with background
[Nsolar project results]
9 N. Ferretti, Investorentag PI-Berlin, 30.10.20139 N. Ferretti, BifiPV Workshop, 26.05.2014
Outdoor power logging
Height=30 cmAngle= 25°Area white background: 7m x 5m
Outdoor power logging performed for both the reference and the bifacial module Specific yields comparison to evaluate if for bifacial modules Pmax measured at a defined albedo is suitable for energy yield predictions.
Reference module installed with same conditions.
10 N. Ferretti, Investorentag PI-Berlin, 30.10.201310 N. Ferretti, BifiPV Workshop, 26.05.2014
Specific Yield comparison
DaysSpec. Yield Bif. vs.
Spec. Yield Ref. (%)
11-18 Dec -5.26-13 Jan -1.81-21 Feb -1.3
3-7 Mar -2.5
26 Jan
Snow+1.6
4 Feb Direct Irrad.,
max 800 W/m²+0.9
Specific Yield (KWh/KWp) comparison of bifacial module with reference module.Bifacial Pmax with white background = 285 W
Diffuse Irrad. > Direct Irrad. (except 4 Feb.)
11 N. Ferretti, Investorentag PI-Berlin, 30.10.201311 N. Ferretti, BifiPV Workshop, 26.05.2014
Irradiance December and January
DaysBif. vs.
Ref. (%)
11-18
Dec-5.2
6-13
Jan-1.8
Specific yield comparison
12 N. Ferretti, Investorentag PI-Berlin, 30.10.201312 N. Ferretti, BifiPV Workshop, 26.05.2014
Irradiance February and March
DaysBif. vs.
Ref. (%)
1-21
Feb-1.3
3-7
Mar-2.5
Specific yield comparison
13 N. Ferretti, Investorentag PI-Berlin, 30.10.201313 N. Ferretti, BifiPV Workshop, 26.05.2014
Conclusions and outlook
• Measurement of a bifacial module at STC outdoor under different albedos (up to +20% on Pmax).
• Pmax value measured outdoor reproduced at the flasher at defined backgrounds.
• Comparison of specific yields of a standard module with the bifacialgood match when considering the Pmax value measured with background.
• Next step: Comparison of measured energy yield with simulation results.
Top Related