The influence of textured surfaces of solar cells and modules on the ...
The influence of textured surfaces of solar cells and modules on the ...
The influence of textured surfaces of solar cells and modules on the ...
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THE INFLUENCE OF TEXTURED SURFACES<br />
OF SOLAR CELLS AND MODULES ON THE<br />
ENERGY RATING OF PV SYSTEMS<br />
P. Grunow 1 , D. Sauter 1 , V. H<str<strong>on</strong>g>of</str<strong>on</strong>g>fmann 1 , D. Huljić 1 , B.Litzenburger 2 , L. Podlowski 2<br />
1<br />
Q-Cells AG, Guardianstr. 16, D-06766 Thalheim, Germany, ph<strong>on</strong>e: +49 3494 6686 -0, fax: -10, email: p.grunow@q-<str<strong>on</strong>g>cells</str<strong>on</strong>g>.com<br />
2<br />
Sol<strong>on</strong> PV GmbH, Ederstr. 16, D-12059 Berlin, Germany, ph<strong>on</strong>e: +49 30 818 79 -100, fax: -110, email: l.podlowski@sol<strong>on</strong>-pv.com; b.litzenburger@sol<strong>on</strong>-pv.com<br />
Motivati<strong>on</strong><br />
Beside <strong>the</strong> need for fur<strong>the</strong>r efficiency increase <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
photovoltaic systems, <strong>the</strong>ir ec<strong>on</strong>omic benefit<br />
depends <strong>on</strong> <strong>the</strong>ir energy ratings. Weak light<br />
performance [1], temperature dependence <str<strong>on</strong>g>and</str<strong>on</strong>g><br />
degradati<strong>on</strong> [2] <str<strong>on</strong>g>of</str<strong>on</strong>g> PV <str<strong>on</strong>g>modules</str<strong>on</strong>g> are already well<br />
investigated. This work investigates <strong>the</strong> <str<strong>on</strong>g>influence</str<strong>on</strong>g><br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angular dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> short circuit<br />
current <strong>on</strong> <strong>the</strong> annual yield due to different surface<br />
texturisati<strong>on</strong> for <strong>the</strong> <str<strong>on</strong>g>cells</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g> <strong>the</strong> cover glass <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
module with a special focus <strong>on</strong> <strong>the</strong> reliability <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
measurement technique used so far [3][4]. <str<strong>on</strong>g>The</str<strong>on</strong>g><br />
relative annual energy yields are calculated with an<br />
adjusted s<str<strong>on</strong>g>of</str<strong>on</strong>g>tware tool.<br />
Angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc: outdoor<br />
θ<br />
rotati<strong>on</strong><br />
Fig. 1: SOLON Mover in Berlin Adlersh<str<strong>on</strong>g>of</str<strong>on</strong>g> used for outdoor<br />
measuremnet <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc angle dependence.Twelve 500W<br />
<str<strong>on</strong>g>modules</str<strong>on</strong>g> equipped with Q6M m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g><br />
Saint-Gobaint Diamant cover Glass are moved by a 2-axistracker.<br />
Isc/A<br />
7<br />
6<br />
5<br />
4<br />
3<br />
2<br />
1<br />
0<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
incident angle θ<br />
total Isc<br />
Isc from diffuse<br />
irradiati<strong>on</strong><br />
Fig. 2: Angle dependence measured outdoors <strong>on</strong> <strong>the</strong> right<br />
center module <str<strong>on</strong>g>of</str<strong>on</strong>g> a SOLON Mover (12 x 500W) equiped with<br />
Q6M m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g> Saint-Gobaint Diamant cover<br />
glass. <str<strong>on</strong>g>The</str<strong>on</strong>g> el<strong>on</strong>gati<strong>on</strong> was varied between 60° <str<strong>on</strong>g>and</str<strong>on</strong>g> -30° to <strong>the</strong><br />
horiz<strong>on</strong>tal positi<strong>on</strong> at a fixed azimuth positi<strong>on</strong><br />
Angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc: indoor<br />
Comparis<strong>on</strong> <str<strong>on</strong>g>and</str<strong>on</strong>g> Correcti<strong>on</strong><br />
Cell type (texturisati<strong>on</strong>)<br />
glass type (texturisati<strong>on</strong>)<br />
#1 Q6M m<strong>on</strong>o (pyramids) Diamant (flat)<br />
#2 Q6M m<strong>on</strong>o (pyramids) Albarino T (weak <str<strong>on</strong>g>textured</str<strong>on</strong>g>)<br />
#3 Q6M m<strong>on</strong>o (pyramids) Albarino P (pyramids)<br />
#4 Q6L multi (n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g>) Diamant (flat)<br />
#5 Q6L multi (n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g>) Albarino T (weak <str<strong>on</strong>g>textured</str<strong>on</strong>g>)<br />
#6 Q6L multi (n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g>) Albarino P (pyramids)<br />
3 mm co ver glass Wh ite<br />
bac k<br />
sheet<br />
Blac kTedlar<br />
frame in <strong>the</strong><br />
laminate<br />
Isc/cos θ<br />
120%<br />
110%<br />
100%<br />
90%<br />
80%<br />
70%<br />
60%<br />
50%<br />
40%<br />
plane glass transmissi<strong>on</strong><br />
indoor (Lab. 1)<br />
indoor (Lab. 2)<br />
indoor (Lab. 3)<br />
outdoor<br />
outdoor - diffuse irrad.<br />
Q6M m<strong>on</strong>o<br />
Diamant glass<br />
30%<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
incident angle θ<br />
Table 1: Samples with various cell <str<strong>on</strong>g>and</str<strong>on</strong>g> cover glass<br />
texturisati<strong>on</strong> used<br />
Fig. 3: Single-cell-module with white Tedlar as back sheet<br />
<str<strong>on</strong>g>and</str<strong>on</strong>g> a black Tedlar frame laminated inside with 3mm<br />
distance to <strong>the</strong> cell<br />
Fig. 4: Indoor measurements <strong>on</strong> <strong>the</strong> same system show large<br />
differences. <str<strong>on</strong>g>The</str<strong>on</strong>g> outdoor measurement <str<strong>on</strong>g>of</str<strong>on</strong>g> Q6M with Diamant<br />
cover glass was used as a st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard reference after substracti<strong>on</strong><br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> n<strong>on</strong>-anle-dependent diffuse comp<strong>on</strong>ent <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> irradiati<strong>on</strong><br />
Re-Calculated results<br />
Isc/cos θ<br />
Isc/cos θ<br />
100%<br />
90%<br />
80%<br />
70%<br />
60%<br />
50%<br />
40%<br />
100%<br />
90%<br />
80%<br />
70%<br />
60%<br />
50%<br />
40%<br />
Q6M Diamant<br />
Q6M Alberino T<br />
Q6M Alberino P<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
Q6L Diamant<br />
Q6L Alberino T<br />
Q6L Alberino P<br />
incident angle θ<br />
Fig. 5: Q6M m<strong>on</strong>o single-cell <str<strong>on</strong>g>modules</str<strong>on</strong>g> as used for indoor<br />
measurements re-calculated to <strong>the</strong> outdoor reference<br />
st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard from Fig. 4<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
incident angle θ<br />
Fig. 6: Q6L multi single-cell <str<strong>on</strong>g>modules</str<strong>on</strong>g> as used for indoor<br />
measurements re-calculated to <strong>the</strong> outdoor reference st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard<br />
from Fig. 4<br />
Annual Energy Yields<br />
Irradiati<strong>on</strong> Data METEONORM: H_Dh, H_Bh, hs, Az, Ta<br />
rel. anual energy yield<br />
Modified Irradiati<strong>on</strong> Data*: H_Dh*, H_Bh*, hs, Az, Ta<br />
104%<br />
104%<br />
103%<br />
103%<br />
102%<br />
102%<br />
101%<br />
101%<br />
100%<br />
100%<br />
99%<br />
Diffuse comp<strong>on</strong>ent<br />
Q6M m<strong>on</strong>o<br />
Q6L multi<br />
Angle dependent Isc(θ)<br />
Annual Yield Simulati<strong>on</strong> Tool<br />
Diamant Albarino T Albarino P<br />
cover glass type<br />
Direct comp<strong>on</strong>ent<br />
Table 2: Calculati<strong>on</strong> scheme for <strong>the</strong> aditi<strong>on</strong>al c<strong>on</strong>siderati<strong>on</strong><br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angle dependent Isc in <strong>the</strong> annual energy yield<br />
Fig. 7: Relative energy yields calculated for <strong>the</strong> sytems<br />
shown in Fig.5&6. <str<strong>on</strong>g>The</str<strong>on</strong>g> additi<strong>on</strong>al c<strong>on</strong>siderati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angle<br />
dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc calculates to 10% lower energy yields<br />
C<strong>on</strong>clusi<strong>on</strong><br />
• <str<strong>on</strong>g>The</str<strong>on</strong>g> experimental c<strong>on</strong>diti<strong>on</strong>s are very difficult to<br />
c<strong>on</strong>trol for indoor measurements. <str<strong>on</strong>g>The</str<strong>on</strong>g>refore <strong>on</strong>ly<br />
relative variati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angle dependence should<br />
be used from indoor measurements <str<strong>on</strong>g>and</str<strong>on</strong>g> an outdoor<br />
measurement <strong>on</strong> a identical system should be used<br />
as a reference st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard.<br />
• <str<strong>on</strong>g>The</str<strong>on</strong>g> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc was integrated in<br />
<strong>the</strong> annual yield simulati<strong>on</strong> by modifying <strong>the</strong> used<br />
irradiati<strong>on</strong> data from METEONORM according to<br />
<strong>the</strong> sun height (hs) <str<strong>on</strong>g>and</str<strong>on</strong>g> azimuth (Az) given <strong>the</strong>rein.<br />
• Pyramid-like structured glass leads to 3% more<br />
annual energy yield compared to flat glass due to<br />
an improved angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc.<br />
• <str<strong>on</strong>g>The</str<strong>on</strong>g> texturisati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> <str<strong>on</strong>g>cells</str<strong>on</strong>g> shows no or very little<br />
<str<strong>on</strong>g>influence</str<strong>on</strong>g> <strong>on</strong> <strong>the</strong> annual yield for flat <str<strong>on</strong>g>and</str<strong>on</strong>g> pyramidlike<br />
structured glass.<br />
References<br />
1. P. Grunow, S. Lust, D. Sauter, V. H<str<strong>on</strong>g>of</str<strong>on</strong>g>fmann, C. Beneking; B.Litzenburger,<br />
L.Podlowski, Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 19th PVSEC, Paris (2004) S. 2190 <str<strong>on</strong>g>and</str<strong>on</strong>g> H.<br />
Müllejans, A. R. Burgers, R. Kenny, E. D. Dunlop, Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 19th PVSEC,<br />
Paris (2004) S. 2455<br />
2. Y. Hishikawa, K. Morita , Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 3rd PV World C<strong>on</strong>ference, Osaka,<br />
(2003)<br />
3. P. Grunow, D. Sauter, V. H<str<strong>on</strong>g>of</str<strong>on</strong>g>fmann, D. Huljić, B. Litzenburger, L.<br />
Podlowski, 20th Symposium Photovoltaische Solarenergie, Bad Staffelstein,<br />
(2005), p. 367.<br />
4. U. Blieske, T. Doege, P. Gayout, M. Ne<str<strong>on</strong>g>and</str<strong>on</strong>g>er, D. Neumann, A. Prat, Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
<strong>the</strong> 3rd PV World C<strong>on</strong>ference, Osaka, (2003), S. 188- 191 Vol.1
THE INFLUENCE OF TEXTURED SURFACES OF SOLAR CELLS AND MODULES ON THE ENERGY<br />
RATING OF PV SYSTEMS<br />
P. Grunow 1 , D. Sauter 1 , V. H<str<strong>on</strong>g>of</str<strong>on</strong>g>fmann 1 , D. Huljić 1 , B. Litzenburger 2 , L. Podlowski 2<br />
1 Q-Cells AG, Guardianstr. 16, D-06766 Thalheim, Germany,<br />
email: p.grunow@q-<str<strong>on</strong>g>cells</str<strong>on</strong>g>.com<br />
2 Sol<strong>on</strong> PV GmbH, Ederstr. 16, D-12059 Berlin, Germany, email: l.podlowski@sol<strong>on</strong>-pv.com<br />
ABSTRACT: <str<strong>on</strong>g>The</str<strong>on</strong>g> energy yield <str<strong>on</strong>g>of</str<strong>on</strong>g> photovoltaic systems has become a key parameter in additi<strong>on</strong> to its maximum<br />
power under st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard testing c<strong>on</strong>diti<strong>on</strong>s (STC). Commercially available simulati<strong>on</strong> s<str<strong>on</strong>g>of</str<strong>on</strong>g>tware availableto predict <strong>the</strong><br />
annual energy yield <strong>on</strong> <strong>the</strong> basis <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> temperature coefficients, <strong>the</strong> low light performance <str<strong>on</strong>g>and</str<strong>on</strong>g> initial module<br />
degradati<strong>on</strong>, but do not c<strong>on</strong>sider <strong>the</strong> <str<strong>on</strong>g>influence</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> short circuit current <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> module yet.<br />
Diffuse light accounts for more than 60% <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> global irradiati<strong>on</strong> in Europe, <str<strong>on</strong>g>and</str<strong>on</strong>g> <strong>the</strong> major share <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> direct<br />
irradiati<strong>on</strong> incident <strong>on</strong> <strong>the</strong> module is n<strong>on</strong>-perpendicular.<br />
This paper investigates <strong>the</strong> <str<strong>on</strong>g>influence</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> different surface textures <strong>on</strong> <strong>the</strong> energy rating <str<strong>on</strong>g>of</str<strong>on</strong>g> a module as driven by<br />
differences in <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> short circuit current. <str<strong>on</strong>g>The</str<strong>on</strong>g> angle dependence was measured <strong>on</strong> <str<strong>on</strong>g>modules</str<strong>on</strong>g><br />
with differently <str<strong>on</strong>g>textured</str<strong>on</strong>g> multi- <str<strong>on</strong>g>and</str<strong>on</strong>g> m<strong>on</strong>o-crystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> combined with flat <str<strong>on</strong>g>and</str<strong>on</strong>g> <str<strong>on</strong>g>textured</str<strong>on</strong>g> cover glass. <str<strong>on</strong>g>The</str<strong>on</strong>g><br />
corresp<strong>on</strong>ding annual energy yields were calculated using a modified data set for <strong>the</strong> hourly irradiati<strong>on</strong> data, which<br />
takes <strong>the</strong> angle dependence into account.<br />
Keywords: energy rating, texturisati<strong>on</strong>, crystalline silic<strong>on</strong><br />
1 INTRODUCTION<br />
Beside <strong>the</strong> need to increase <strong>the</strong> rated efficiency <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
photovoltaic systems, energy ratings are <strong>the</strong> key<br />
parameter for <strong>the</strong>ir ec<strong>on</strong>omic benefit. S<str<strong>on</strong>g>of</str<strong>on</strong>g>tware<br />
simulati<strong>on</strong> programs are widely used to predict <strong>the</strong><br />
annual yield <str<strong>on</strong>g>of</str<strong>on</strong>g> photovoltaic systems for a given locati<strong>on</strong>.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> module parameters <strong>the</strong>rein are <strong>the</strong> electrical<br />
parameters at st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard testing c<strong>on</strong>diti<strong>on</strong>s (STC) toge<strong>the</strong>r<br />
with <strong>the</strong>ir temperature dependence, low light<br />
performance [1] <str<strong>on</strong>g>and</str<strong>on</strong>g> degradati<strong>on</strong> [2] in some cases. All<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong>se module parameters refer to perpendicular<br />
irradiati<strong>on</strong>, but incident angles > 0 are pre-dominant<br />
under field c<strong>on</strong>diti<strong>on</strong>s for n<strong>on</strong>-tracking systems. <str<strong>on</strong>g>The</str<strong>on</strong>g><br />
angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> short circuit current is not used<br />
as a parameter in <strong>the</strong> existing s<str<strong>on</strong>g>of</str<strong>on</strong>g>tware simulati<strong>on</strong> tools,<br />
although <strong>the</strong>re has been d<strong>on</strong>e a lot <str<strong>on</strong>g>of</str<strong>on</strong>g> work <strong>on</strong> annual<br />
angular reflecti<strong>on</strong> losses [3] <str<strong>on</strong>g>and</str<strong>on</strong>g> realistic reporting<br />
c<strong>on</strong>diti<strong>on</strong>s (RRC) [4], including <strong>the</strong> preparati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> an<br />
internati<strong>on</strong>al regulati<strong>on</strong> [5]. This work investigates <strong>the</strong><br />
<str<strong>on</strong>g>influence</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc <strong>on</strong> <strong>the</strong><br />
annual yield with a special focus <strong>on</strong> <strong>the</strong> reliability <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
measurement technique used[6][7]. <str<strong>on</strong>g>The</str<strong>on</strong>g> relative annual<br />
energy yields for chosen sample <str<strong>on</strong>g>modules</str<strong>on</strong>g> are calculated<br />
with an adjusted s<str<strong>on</strong>g>of</str<strong>on</strong>g>tware tool by modifying <strong>the</strong> annual<br />
hourly irradiati<strong>on</strong> data set.<br />
circuit Isc <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> samples was measured <strong>on</strong> three different<br />
sun simulators each using <strong>the</strong> same measurement<br />
principle for <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc, i.e. a<br />
measurement stage, which allowed tilting <strong>the</strong> sample<br />
between incident angles θ <str<strong>on</strong>g>of</str<strong>on</strong>g> 0° (perpendicular) <str<strong>on</strong>g>and</str<strong>on</strong>g> 90°.<br />
Cell type (texturisati<strong>on</strong>) Glass type (texturisati<strong>on</strong>)<br />
#1 Q6M m<strong>on</strong>o (pyramids) Diamant (flat)<br />
#2 Q6M m<strong>on</strong>o (pyramids) Albarino T(weak <str<strong>on</strong>g>textured</str<strong>on</strong>g>)<br />
#3 Q6M m<strong>on</strong>o (pyramids) Albarino P (2mm pyramids)<br />
#4 Q6L multi (n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g>) Diamant (flat)<br />
#5 Q6L multi (n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g>) Albarino T (weak <str<strong>on</strong>g>textured</str<strong>on</strong>g>)<br />
#6 Q6L multi (n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g>) Albarino P (2mm pyramids)<br />
Table I: samples for indoor measurements<br />
3 mm cover glass White<br />
back<br />
sheet<br />
Black Tedlar<br />
frame in <strong>the</strong><br />
laminate<br />
2 MEASUREMENTS<br />
2.1 Indoor measurements<br />
Six single-cell-<str<strong>on</strong>g>modules</str<strong>on</strong>g> were prepared using two<br />
different <str<strong>on</strong>g>cells</str<strong>on</strong>g> types from Q-Cells <str<strong>on</strong>g>and</str<strong>on</strong>g> three different<br />
glass types from Saint Gobain Glass, see Table 1. All<br />
glass samples were 3 mm thick. <str<strong>on</strong>g>The</str<strong>on</strong>g> 156 mm<br />
multicrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> Q6L were alkaline etched resulting<br />
in nearly n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g> surface <str<strong>on</strong>g>and</str<strong>on</strong>g> <strong>the</strong> 150 mm<br />
m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> Q6M were <str<strong>on</strong>g>textured</str<strong>on</strong>g> in <strong>the</strong> classical<br />
alkaline/ethanol bath resulting in <strong>the</strong> well-known<br />
pyramid structure with a very good texturisati<strong>on</strong> effect.<br />
White Tedlar back sheets were used for <strong>the</strong> encapsulati<strong>on</strong><br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> single-cell <str<strong>on</strong>g>modules</str<strong>on</strong>g>, with black Tedlar laminated<br />
inside to form a frame with a surrounding gap <str<strong>on</strong>g>of</str<strong>on</strong>g> 3 mm to<br />
<strong>the</strong> single cell in <strong>the</strong> center, see Figure 1. <str<strong>on</strong>g>The</str<strong>on</strong>g> short<br />
Figure 1: Single-cell-module used for indoor<br />
measurements<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> measured angle dependences <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc were found<br />
to be very dependent <strong>on</strong> <strong>the</strong> set-up. Possible reas<strong>on</strong>s are<br />
misalignment errors <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> rotating axis, scattered light<br />
from <strong>the</strong> simulator walls, effects from <strong>the</strong> n<strong>on</strong>homogenously<br />
illuminated area at large incident angles for<br />
large cell areas. Masking <strong>the</strong> cell from <strong>the</strong> full area down to<br />
a spot <str<strong>on</strong>g>of</str<strong>on</strong>g> 1 mm² showed differences in <strong>the</strong> results, when<br />
ei<strong>the</strong>r a vertical tube aperture or a horiz<strong>on</strong>tal mask was<br />
used. For this reas<strong>on</strong> <strong>on</strong>ly relative results were used from<br />
<strong>the</strong> indoor measurements with no additi<strong>on</strong>al masking.
2.1 Outdoor measurements<br />
Outdoor measurements were performed with a large 2-<br />
axis tracker hosting twelve 500 Watt <str<strong>on</strong>g>modules</str<strong>on</strong>g> (“Mover”<br />
from Sol<strong>on</strong>-PV GmbH). <str<strong>on</strong>g>The</str<strong>on</strong>g> 500 Watt <str<strong>on</strong>g>modules</str<strong>on</strong>g> c<strong>on</strong>sist <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
6 mm Diamant cover glass, white Tedlar back sheet <str<strong>on</strong>g>and</str<strong>on</strong>g> 80<br />
series c<strong>on</strong>nected Q6M m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> with a cell-tocell<br />
distance <str<strong>on</strong>g>of</str<strong>on</strong>g> 3 mm. <str<strong>on</strong>g>The</str<strong>on</strong>g> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc<br />
was measured for a center module (Sol<strong>on</strong> SerNo. 217365)<br />
from perpendicular to horiz<strong>on</strong>tal irradiance in steps <str<strong>on</strong>g>of</str<strong>on</strong>g> 5°<br />
by using <strong>the</strong> automatic c<strong>on</strong>trol <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 2 axis tracker in<br />
manual mode.<br />
In a sec<strong>on</strong>d run, <strong>the</strong> module was rotated in horiz<strong>on</strong>tal<br />
positi<strong>on</strong> around its sec<strong>on</strong>d axis (“helicopter mode”) to<br />
investigate <strong>the</strong> effect <str<strong>on</strong>g>of</str<strong>on</strong>g> various orientati<strong>on</strong>s between <strong>the</strong><br />
plane <str<strong>on</strong>g>of</str<strong>on</strong>g> incidence <str<strong>on</strong>g>and</str<strong>on</strong>g> <strong>the</strong> cell edge orientati<strong>on</strong>. <str<strong>on</strong>g>The</str<strong>on</strong>g> angle<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> incidence was 40°, i.e. <strong>the</strong> sun height was hs = 50°.<br />
Figure 2: 2-axis tracker used for outdoor angle<br />
dependence measurement <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc (“Mover” from<br />
Sol<strong>on</strong>-PV GmbH; Pmax = 6kW at STC)<br />
3 RESULTS<br />
3.1 Tilt axis orientati<strong>on</strong><br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> orientati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> axis showed <strong>on</strong>ly minor<br />
<str<strong>on</strong>g>influence</str<strong>on</strong>g> <strong>on</strong> <strong>the</strong> Isc, see Figure 3.<br />
change in Isc<br />
5%<br />
4%<br />
3%<br />
2%<br />
1%<br />
0%<br />
-1%<br />
-2%<br />
-3%<br />
-4%<br />
-5%<br />
θ<br />
-180° -135° -90° -45° 0°<br />
rotati<strong>on</strong><br />
rotati<strong>on</strong><br />
Mover in "helicopter mode;<br />
angle <str<strong>on</strong>g>of</str<strong>on</strong>g> incidence = 40°<br />
Figure 3: Rotating module under a fixed angle <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
incidence <str<strong>on</strong>g>of</str<strong>on</strong>g> 40°, sun height = 50°<br />
For 0° <str<strong>on</strong>g>and</str<strong>on</strong>g> 180° <strong>the</strong> fingers <strong>on</strong> <strong>the</strong> cell are<br />
perpendicular to <strong>the</strong> plane <str<strong>on</strong>g>of</str<strong>on</strong>g> incidence. <str<strong>on</strong>g>The</str<strong>on</strong>g> increase <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
<strong>the</strong> Isc for orientati<strong>on</strong>s between -45° <str<strong>on</strong>g>and</str<strong>on</strong>g> -135° by 1% is<br />
attributed to <strong>the</strong> reduced shading effect <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> screen<br />
printed fingers <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> <str<strong>on</strong>g>cells</str<strong>on</strong>g>, when <strong>the</strong> plane <str<strong>on</strong>g>of</str<strong>on</strong>g> incidence is<br />
parallel to <strong>the</strong> fingers. With a 2.1 mm distance between<br />
<strong>the</strong> fingers <str<strong>on</strong>g>and</str<strong>on</strong>g> a height <str<strong>on</strong>g>of</str<strong>on</strong>g> 15 µm height this calculates to<br />
0.6% shading loss for <strong>the</strong> used incident angle <str<strong>on</strong>g>of</str<strong>on</strong>g> 40° in<br />
<strong>the</strong> perpendicular case. For <strong>the</strong> sake <str<strong>on</strong>g>of</str<strong>on</strong>g> unified<br />
measurement c<strong>on</strong>diti<strong>on</strong>s, all measurement in <strong>the</strong><br />
following were performed with <strong>the</strong> fingers orientati<strong>on</strong><br />
perpendicular to <strong>the</strong> plane <str<strong>on</strong>g>of</str<strong>on</strong>g> incidence<br />
3.2 Comparis<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> incident angle measurements<br />
As already discussed, <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc<br />
depends highly <strong>on</strong> <strong>the</strong> simulators used, see Fig. 5 for <strong>the</strong><br />
system Q6M m<strong>on</strong>o with flat Diamant glass.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> outdoor measurement <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> same system was<br />
c<strong>on</strong>sidered to be <strong>the</strong> most reliable measurement approach<br />
for <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc because <str<strong>on</strong>g>of</str<strong>on</strong>g> two<br />
reas<strong>on</strong>s:<br />
1. <str<strong>on</strong>g>The</str<strong>on</strong>g> perfect homogeneity <str<strong>on</strong>g>and</str<strong>on</strong>g> parallelism <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
irradiati<strong>on</strong> under clear sky c<strong>on</strong>diti<strong>on</strong>s avoids<br />
misalignment <str<strong>on</strong>g>and</str<strong>on</strong>g> geometric errors even when tilting<br />
larger samples.<br />
2. <str<strong>on</strong>g>The</str<strong>on</strong>g> use <str<strong>on</strong>g>of</str<strong>on</strong>g> a complete module inside a PV system<br />
avoids <strong>the</strong> effect <str<strong>on</strong>g>of</str<strong>on</strong>g> undiscovered parameters given by <strong>the</strong><br />
module design in original scale or <strong>the</strong> module fixtures.<br />
Figure 4 shows <strong>the</strong> raw data <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc measurement<br />
<strong>on</strong> <strong>the</strong> Mover in Adlersh<str<strong>on</strong>g>of</str<strong>on</strong>g>, Berlin measured <strong>on</strong> a sunny<br />
day with clear sky tilting <strong>the</strong> Mover between 60° <str<strong>on</strong>g>and</str<strong>on</strong>g><br />
-30° vs. its horiz<strong>on</strong>tal positi<strong>on</strong>. <str<strong>on</strong>g>The</str<strong>on</strong>g> total outdoor<br />
measurement <strong>on</strong> <strong>the</strong> “Mover” took 15 min corresp<strong>on</strong>ding<br />
to a change <str<strong>on</strong>g>of</str<strong>on</strong>g> 2° in <strong>the</strong> sun height. <str<strong>on</strong>g>The</str<strong>on</strong>g> angle <str<strong>on</strong>g>of</str<strong>on</strong>g> incident<br />
was corrected accordingly.<br />
Figure 4: Angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc measured outdoor<br />
<strong>on</strong> a 500 Watt module <str<strong>on</strong>g>of</str<strong>on</strong>g> a “Mover” with Q6M<br />
m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g> Diamant cover glass at<br />
800 W/m²<br />
Isc/cos θ<br />
Isc/A<br />
7<br />
6<br />
5<br />
4<br />
3<br />
2<br />
1<br />
0<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
120%<br />
110%<br />
100%<br />
90%<br />
80%<br />
70%<br />
60%<br />
50%<br />
40%<br />
plane glass transmissi<strong>on</strong><br />
indoor (Lab. 1)<br />
indoor (Lab. 2)<br />
indoor (Lab. 3)<br />
outdoor<br />
incident angle θ<br />
outdoor - diffuse irrad.<br />
30%<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
incident angle θ<br />
total Isc<br />
Isc from diffuse<br />
irradiati<strong>on</strong><br />
Q6M m<strong>on</strong>o<br />
Diamant glass<br />
Figure 5: Angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc for Q6M<br />
m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> <str<strong>on</strong>g>and</str<strong>on</strong>g> Diamant cover glass measured<br />
indoor at three different laboratories <str<strong>on</strong>g>and</str<strong>on</strong>g> outdoor <strong>on</strong> a<br />
“Mover” in Adlersh<str<strong>on</strong>g>of</str<strong>on</strong>g>, Berlin, Germany.
<str<strong>on</strong>g>The</str<strong>on</strong>g> diffuse radiati<strong>on</strong> comp<strong>on</strong>ent <str<strong>on</strong>g>and</str<strong>on</strong>g> <strong>the</strong> effect <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
illuminated area decrease for <strong>the</strong> tilted module area in <strong>the</strong><br />
outdoor data in Fig. 4 were eliminated from <strong>the</strong> raw data<br />
as follows:<br />
( θ ) − I<br />
SC<br />
( 90°<br />
)<br />
( 0°<br />
) − I ( 90°<br />
)<br />
I<br />
SC<br />
I<br />
SC<br />
cosθ<br />
=<br />
cos θ (1)<br />
I<br />
SC<br />
SC<br />
Isc/cos θ<br />
100%<br />
90%<br />
80%<br />
70%<br />
For <strong>the</strong> subtracti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> diffuse comp<strong>on</strong>ent it was<br />
assumed that <strong>the</strong> diffuse irradiati<strong>on</strong> does not depend <strong>on</strong><br />
<strong>the</strong> tilt angle <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Mover against its horiz<strong>on</strong>tal positi<strong>on</strong><br />
between 60° <str<strong>on</strong>g>and</str<strong>on</strong>g> -30°. Because <strong>the</strong> collecti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> diffuse<br />
irradiati<strong>on</strong> is most effective for <strong>the</strong> Mover in <strong>the</strong><br />
horiz<strong>on</strong>tal positi<strong>on</strong>, this assumpti<strong>on</strong> results in lower<br />
values for incident angles around 60°. Using diffuse<br />
distributi<strong>on</strong> as given for <strong>the</strong> reference days in [5] this<br />
error was estimated to be lower than 3% absolute in<br />
Isc/cos.<br />
In Fig. 5, <strong>on</strong>ly <strong>the</strong> outdoor “Mover” data were<br />
corrected for <strong>the</strong> diffuse comp<strong>on</strong>ent <str<strong>on</strong>g>and</str<strong>on</strong>g> are used to<br />
normalize <strong>the</strong> relative indoor data in secti<strong>on</strong> 3.3.<br />
For comparis<strong>on</strong>, <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
transmissi<strong>on</strong> through n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g> planar glass is shown<br />
in Fig. 5. <str<strong>on</strong>g>The</str<strong>on</strong>g> measured angle dependence is greater,<br />
because <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> additi<strong>on</strong>al angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
refecti<strong>on</strong> at <strong>the</strong> encapsulant/cell interface.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> lower IR absorpti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Albarino compared to<br />
Diamant glass results in an Isc increase <str<strong>on</strong>g>of</str<strong>on</strong>g> 1.8% at 0°<br />
incidence for 3 mm thick glass. For <strong>the</strong> same reas<strong>on</strong>, <strong>the</strong><br />
glass thickness has also an effect <strong>on</strong> <strong>the</strong> angle dependence.<br />
In <strong>the</strong> case <str<strong>on</strong>g>of</str<strong>on</strong>g> Diamant glass <strong>the</strong> relative Isc/cos θ at 75°<br />
incidence is by 2% absolute lower for 6 relative to 3 mm<br />
thick glass.<br />
3.3 Angle dependent Isc<br />
Figure 6 <str<strong>on</strong>g>and</str<strong>on</strong>g> 7 gives <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> Isc from<br />
<strong>the</strong> indoor measurements <strong>on</strong> <strong>the</strong> six sample systems in<br />
Table 1 after normalizing to <strong>the</strong> outdoor data for <strong>the</strong> Q6M<br />
m<strong>on</strong>o Diamant system.<br />
100%<br />
60%<br />
50%<br />
40%<br />
Q6L Diamant<br />
Q6L Alberino T<br />
Q6L Alberino P<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
incident angle θ<br />
Figure 7: Angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> Q6L multicrystalline<br />
single-cell-<str<strong>on</strong>g>modules</str<strong>on</strong>g> for different <str<strong>on</strong>g>textured</str<strong>on</strong>g> glass types<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> better result for <strong>the</strong> m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> for<br />
Albarino T can be explained by its lower IR absorpti<strong>on</strong><br />
compared to Diamant. <str<strong>on</strong>g>The</str<strong>on</strong>g> lower absorpti<strong>on</strong> in <strong>the</strong><br />
infrared gives more benefit for <strong>the</strong> m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g><br />
because <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong>ir better spectral resp<strong>on</strong>se in <strong>the</strong> IR.<br />
4 RELATIVE ANNUAL ENERGY YIELDS<br />
4.1 Calculati<strong>on</strong><br />
For <strong>the</strong> calculati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> annual energy yield <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
six systems from Figure 6&7, <strong>the</strong> irradiati<strong>on</strong> data from<br />
<strong>the</strong> data base METEONORM for Frankfurt am Main,<br />
Germany were weighted with <strong>the</strong> measured angle<br />
dependence. This gave six different modified irradiati<strong>on</strong><br />
data sets for each specific system in Table 1. <str<strong>on</strong>g>The</str<strong>on</strong>g>se data<br />
sets were <strong>the</strong>n used as metrological input data to<br />
calculate <strong>the</strong> annual energy yield with a st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard<br />
simulati<strong>on</strong> tool.<br />
Irradiati<strong>on</strong> Data METEONORM: H_Dh, H_Bh, hs, Az, Ta<br />
Angle dependent Isc(θ)<br />
90%<br />
Diffuse comp<strong>on</strong>ent<br />
Direct comp<strong>on</strong>ent<br />
Isc/cos θ<br />
80%<br />
70%<br />
60%<br />
50%<br />
40%<br />
Q6M Diamant<br />
Q6M Alberino T<br />
Q6M Alberino P<br />
0° 10° 20° 30° 40° 50° 60° 70° 80° 90°<br />
incident angle θ<br />
Figure 6: Angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Q6M m<strong>on</strong>ocrystalline<br />
single-cell-<str<strong>on</strong>g>modules</str<strong>on</strong>g> for different <str<strong>on</strong>g>textured</str<strong>on</strong>g> glass types<br />
For both cell types <strong>the</strong> pyramid structured Albarino P<br />
glass cover shows a lower angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc<br />
than <strong>the</strong> flat glass Diamant. This is in good agreement<br />
with results reported elsewhere [6] <str<strong>on</strong>g>and</str<strong>on</strong>g> was explained by<br />
<strong>the</strong> improved geometric optics <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> pyramids lifting <strong>the</strong><br />
incident angle at <strong>the</strong> cell/EVA interface.<br />
Modified Irradiati<strong>on</strong> Data*: H_Dh*, H_Bh*, hs, Az, Ta<br />
Annual Yield Simulati<strong>on</strong> Tool<br />
Table 2: Calculati<strong>on</strong> scheme for <strong>the</strong> effect <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
measured angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc <strong>on</strong> <strong>the</strong> annual<br />
energy yield<br />
4.2 Comparis<strong>on</strong><br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> energy yields for a simulated PV system in<br />
Frankfurt am Main, oriented to <strong>the</strong> south with 30° tilt<br />
angle are summarized in Figure 8 <str<strong>on</strong>g>and</str<strong>on</strong>g> show 3.5% better<br />
yields for Albarino P than for <strong>the</strong> Diamant glass for both<br />
cell types.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> better result for <strong>the</strong> m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g> when<br />
using Albarino T cover glass is explained by <strong>the</strong> lower<br />
infrared absorpti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> Albarino T (<str<strong>on</strong>g>and</str<strong>on</strong>g> P) compared to<br />
Diamant glass. This gives more benefit to <strong>the</strong><br />
m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g>, because <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong>ir better spectral<br />
resp<strong>on</strong>se in <strong>the</strong> infrared. This was not observed for <strong>the</strong>
pyramid structured Albarino P, because <strong>the</strong> pyramids<br />
effectively shorten <strong>the</strong> optical path <str<strong>on</strong>g>and</str<strong>on</strong>g> <strong>the</strong> effect <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
reduced IR absorpti<strong>on</strong> is decreased drastically.<br />
rel. anual energy yield<br />
104%<br />
104%<br />
103%<br />
103%<br />
102%<br />
102%<br />
101%<br />
101%<br />
100%<br />
100%<br />
99%<br />
Q6M m<strong>on</strong>o<br />
Q6L multi<br />
Diamant Albarino T Albarino P<br />
cover glass type<br />
Figure 8: Relative annual yields for all systems at<br />
Frankfurt am Main, oriented to <strong>the</strong> south with 30° tilt<br />
angle<br />
In summary, no differences in <strong>the</strong> energy vields were<br />
observed for different surface texturisati<strong>on</strong> for <strong>the</strong> sample<br />
<str<strong>on</strong>g>cells</str<strong>on</strong>g> used, which were chosen to range from a nearly<br />
n<strong>on</strong>-<str<strong>on</strong>g>textured</str<strong>on</strong>g> surface (multi) to a very effectively <str<strong>on</strong>g>textured</str<strong>on</strong>g><br />
(m<strong>on</strong>o) surface. <str<strong>on</strong>g>The</str<strong>on</strong>g> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc is<br />
mainly affected by <strong>the</strong> texturisati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> glass <str<strong>on</strong>g>and</str<strong>on</strong>g> its<br />
infrared absorpti<strong>on</strong>. For <strong>the</strong> Diamant cover glass, this<br />
result was c<strong>on</strong>firmed by comparing energy yield data<br />
from <strong>the</strong> ro<str<strong>on</strong>g>of</str<strong>on</strong>g> top system at Q-Cells AG in Thalheim,<br />
Germany, for module strings with multi- <str<strong>on</strong>g>and</str<strong>on</strong>g><br />
m<strong>on</strong>ocrystalline <str<strong>on</strong>g>cells</str<strong>on</strong>g>. No significant differences in <strong>the</strong>ir<br />
energy yields were observed for <strong>the</strong> period from February<br />
to May 2005 inside <strong>the</strong> tolerances <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> m<strong>on</strong>itoring<br />
system.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> annual angular reflecti<strong>on</strong> losses, i.e. <strong>the</strong> effect <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
<strong>the</strong> angle dependence <strong>on</strong> <strong>the</strong> calculated annual yield, is<br />
-10% for <strong>the</strong> Q6M Diamant system, while -3% to -4%<br />
was reported earlier for comparable <str<strong>on</strong>g>modules</str<strong>on</strong>g> in Europe<br />
[3]. This is due to <strong>the</strong> str<strong>on</strong>ger angle dependence found<br />
for <strong>the</strong> outdoor measurements. Fur<strong>the</strong>r verificati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> this<br />
measurements <str<strong>on</strong>g>and</str<strong>on</strong>g> its correcti<strong>on</strong> are necessary to clarify<br />
this deviati<strong>on</strong>.<br />
6 ACKNOWLEDGEMENTS<br />
We would like to thank U. Blieske, N.-P. Harder, U.<br />
Blieske <str<strong>on</strong>g>and</str<strong>on</strong>g> F. Best from Saint-Gobain Glass<br />
Deutschl<str<strong>on</strong>g>and</str<strong>on</strong>g> for fruitful discussi<strong>on</strong>s, glass samples <str<strong>on</strong>g>and</str<strong>on</strong>g><br />
additi<strong>on</strong>al measurements, B. Michaelis for performing<br />
most <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> indoor measurements, S. Lehmann for <strong>the</strong><br />
outdoor measurements <strong>on</strong> <strong>the</strong> Sol<strong>on</strong> Mover in Adlersh<str<strong>on</strong>g>of</str<strong>on</strong>g><br />
Berlin, M. Mette for <strong>the</strong> data evaluati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> ro<str<strong>on</strong>g>of</str<strong>on</strong>g> top<br />
system at Q-Cells AG <str<strong>on</strong>g>and</str<strong>on</strong>g> Pr<str<strong>on</strong>g>of</str<strong>on</strong>g>. H.-G. Beyer from <strong>the</strong> FH<br />
Magdeburg-Stendal for <strong>the</strong> simulati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> annual yield<br />
data <strong>on</strong> <strong>the</strong> basis <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> angle dependent Isc<br />
measurements with <strong>the</strong> simulati<strong>on</strong> s<str<strong>on</strong>g>of</str<strong>on</strong>g>tware INSEL as<br />
distributed by <strong>the</strong> company Doppelintegral in Stuttgart,<br />
Germany.<br />
7 REFERENCES<br />
[1] P. Grunow, S. Lust, D. Sauter, V. H<str<strong>on</strong>g>of</str<strong>on</strong>g>fmann, C.<br />
Beneking; B.Litzenburger, L.Podlowski, Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
19th PVSEC, Paris (2004) S. 2190 <str<strong>on</strong>g>and</str<strong>on</strong>g> H.<br />
Müllejans, A. R. Burgers, R. Kenny, E. D. Dunlop,<br />
Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 19th PVSEC, Paris (2004) S. 2455<br />
[2] Y. Hishikawa, K. Morita , Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 3rd PV World<br />
C<strong>on</strong>ference, Osaka, (2003)<br />
[3] N. Martin, M.Ruiz Int. J. <str<strong>on</strong>g>of</str<strong>on</strong>g> Solar Energy, 2002,<br />
Vol.22(1),pp.19–31<br />
[4] K. Bücher; True Module Rating; Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 13th<br />
PVSEC, Nizza, France (1995)<br />
[5] IEC/TC82/WG2 working draft IEC 61853, Oktober<br />
(2003)<br />
[6] U. Blieske, T. Doege, P. Gayout, M. Ne<str<strong>on</strong>g>and</str<strong>on</strong>g>er, D.<br />
Neumann, A. Prat, “Light-trapping in <str<strong>on</strong>g>solar</str<strong>on</strong>g> <str<strong>on</strong>g>modules</str<strong>on</strong>g><br />
using extra-white <str<strong>on</strong>g>textured</str<strong>on</strong>g> glass” Proc. <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> 3rd PV<br />
World C<strong>on</strong>ference, Osaka, (2003), p. 188- 191 Vol.1.<br />
[7] P. Grunow, D. Sauter, V. H<str<strong>on</strong>g>of</str<strong>on</strong>g>fmann, D. Huljić, B.<br />
Litzenburger, L. Podlowski, 20 th Symposium<br />
Photovoltaische Solarenergie, Bad Staffelstein,<br />
(2005), p. 367.<br />
5 CONCLUSION<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> experimental c<strong>on</strong>diti<strong>on</strong>s for angle dependent Isc<br />
measurements are very difficult to c<strong>on</strong>trol for indoor<br />
measurements. <str<strong>on</strong>g>The</str<strong>on</strong>g>refore <strong>on</strong>ly relative variati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong><br />
angle dependence are used from indoor measurements<br />
<str<strong>on</strong>g>and</str<strong>on</strong>g> an outdoor measurement <strong>on</strong> an identical system is<br />
used as a reference st<str<strong>on</strong>g>and</str<strong>on</strong>g>ard.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc was taken into<br />
account in <strong>the</strong> calculati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> annual yield by<br />
modifying <strong>the</strong> local annual irradiati<strong>on</strong> data from<br />
METEONORM according to <strong>the</strong> sun height (hs) <str<strong>on</strong>g>and</str<strong>on</strong>g><br />
azimuth (Az).<br />
Pyramid-like structured glass leads to 3.5% more<br />
annual energy yield compared to flat glass due to an<br />
improved angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> texturisati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> <str<strong>on</strong>g>cells</str<strong>on</strong>g> shows n<strong>on</strong>e or very little<br />
<str<strong>on</strong>g>influence</str<strong>on</strong>g> <strong>on</strong> <strong>the</strong> annual yield for flat <str<strong>on</strong>g>and</str<strong>on</strong>g> pyramid-like<br />
structured glass. Glass with low infrared absorpti<strong>on</strong> is<br />
beneficial for <strong>the</strong> angle dependence <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> Isc especially<br />
for <str<strong>on</strong>g>cells</str<strong>on</strong>g> with improved spectral resp<strong>on</strong>se in <strong>the</strong> infrared.