6 h. nussbaumer - zhaw ok

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


Power distribution / storage

Germany 2014


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


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


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


Solution 1: Energy storage Peak shift - battery storage & costs

⇒Energy storage triples the conventional cost of the generated PV energy-

⇒Are there alternatives?


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


Solution 2 Measurement results: +8.4% Power @ 2014-05-18

5

8

11

14

8 17

20

Irradiance Power East/West Power South

Net load predicted in the future for California


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?


Reason for +8.4%: Temperature? Anlaysis Voc East/West versus South


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


Simulation with PVsyst

Albedo 0.2 6 8:45 16:30 14

Measured data

Power

Simulated data


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


Solution 2: Impact With bi-facial less peak shift is needed!


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.


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

Presentations & Public Speaking

6 h. nussbaumer - zhaw ok