New opportunities of grid integration by the use of bifacial modules

1. Zürcher Fachhochschule
New opportunities for a better power
distribution by the use of bifacial
modules in future PV systems
H. Nussbaumer, F. Baumgartner, T. Baumann, D. Schär, F. Carigiet,
ZHAW Winterthur Switzerland
C. Comparotto, R. Harney, A. Schneider,
ISC Konstanz, Germany

2. Zürcher Fachhochschule
Power distribution / storage
Germany 2014

3. Zürcher Fachhochschule
Net load will shift to 18:00 +
trends for California, US
=> Reduction due to self use of PV energy produced!-
=> Energy needed in the evening for charging electrical vehicels

4. Zürcher Fachhochschule
Power distribution / storage
⇒In the near future many regions will face the problem
of an over PV capacity during midday and too low
capacity in the evening
⇒What solutions are available?
Energy storage or
other energy production profiles
other PV mounting solutions

5. Zürcher Fachhochschule
Solution 1: Energy storage
Peak shift - battery storage & costs
N. Kreutzer, C. Allert, J. Weide, M. Rothert, F. Thim; 4BV.1.31
25th European Photovoltaic Solar Energy Conference /5th World Conference
on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain
produce it
0.15 €/kWh
store it
> 0.35 €/kWh+ = use it
> 0.50 €/kWh
4 person household
5kW PV
20% to 40%
PV selfe consumption
0.74€/kWh; F. Baumgartner et. al. EUPVSEC 2012, Plenary Talk, www.zhaw.ch/~bauf

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Solution 1: Energy storage
Peak shift - battery storage & costs
⇒Energy storage triples the conventional cost of the
generated PV energy-
⇒Are there alternatives?

7. Zürcher Fachhochschule
Solution 2: Bifacial modules?
Measurement - Setup
• Bifacial: vertical - azimuth 90° Pn1=255.6 / 232.6 WSTC
• Bifacial: 30° inclination / azimuth 0° Pn2=255.3 / 231.7 WSTC

8. Zürcher Fachhochschule
Solution 2
Measurement results:
+8.4% Power @ 2014-05-18
5 8 11 14 817 20
Irradiance
Power East/West
Power South
Net load predicted in the future
for California

9. Zürcher Fachhochschule
Solution 2
Measurement results:
+8.4% Power @ 2014-05-18
⇒A bifacial solar module with east/west orientation has
a much better broader power distribution
⇒Compared to the south oriented bifacial modules the
energy harvest is increased by 8.4%!!
⇒What is the reason for the higher energy harvest
and what is the impact on the cost of the PV energy
in the future?

10. Zürcher Fachhochschule
Reason for +8.4%: Temperature?
Anlaysis Voc East/West versus South

11. Zürcher Fachhochschule
Simulation of bifacial modules
• Simulation parameters based on standard PV design tools
– 2 standard modules = 1 bifi module
– Albedo = 0.2
Degree of area utilization 𝑓𝑓 = 𝑏𝑏/𝑑𝑑
Bifi Module simulated
d = Distance between modules
S
b

12. Zürcher Fachhochschule
Simulation with PVsyst
Albedo 0.2
6 8:45 16:3014
Measured data
Power
Simulated data

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Reason for +8.4%
Anlaysis Voc East/West versus South
⇒The temperature of the east/west module is lower
during the time of maximum irradiance as compared
to the south oriented module- advantage!
⇒The main reason for the higher energy harvest of the
east/west orientation is assumed to be the better
collection of the irradiation – to be verified annually
⇒Simulation with standard tools using two standard
modules cannot simulate the bifacial module yet-
further investigation needed
⇒ Shading can be an issue with east/west orientation

14. Zürcher Fachhochschule
Solution 2: Impact
With bi-facial less peak shift is
needed!

15. Zürcher Fachhochschule
Conclusion
• Bifacial modules in combination with new installation and
orientation offer new advantages to integrate PV electricity
into the grid.
⇒In the near future, this will save money for costly energy
storage
• New orientations and different installation may result in an
additional energy harvest as compared to conventional
mounting (in example south orientation). Albedo and shading
aspects have to be considered and carefully measured.

16. Zürcher Fachhochschule
Outlook
⇒We will develop new mounting systems for bifacial
modules
⇒We have to develop new simulation tools for bifacial
modules
⇒Standardized measurement conditions have to be
defined and compared with real data from the field