New opportunities of grid integration by the use of bifacial modules

Transcription

1 New opportunities of grid integration by the use of bifacial modules H. Nussbaumer, T. Baumann, F. Carigiet, N. Keller, D. Schär, F. Baumgartner

2 ZHAW SoE - IEFE PV ZHAW = Zurich University of Applied Sciences Close to students School of Engineering located in Winterthur (~15km away from Zurich) IEFE = Institute of Energy Systems and Fluid Engineering

3 ZHAW SoE - IEFE PV

4 ZHAW SoE - IEFE PV Focus Silicon Wafer Solar cell Module System Integration, Batteries

5 Increasing share of PV Lost energy or energy storage

6 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 We do not only have to think about the maximum energy harvest but also about the load profile! We need energy storage or have to adapt the energy production profile on the load profile

7 Load distribution, example Chile If we want to supply energy to a copper mine we have to ask: What is the load profile of a copper mine?

8 Solution:Energy storage Peak shift - battery storage & costs produce it 0.18 USD/kWh store it + > 0.42 USD/kWh = use it > 0.60 USD/kWh 4 person household 5kW PV 20% to 40% PV self consumption 0.74 /kwh; F. Baumgartner et. al. EUPVSEC 2012, Plenary Talk, N. Kreutzer, C. Allert, J. Weide, M. Rothert, F. Thim; 4BV th European Photovoltaic Solar Energy Conference /5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain

9 Solution: Energy storage Peak shift - battery storage & costs Copper mine Power store it > 0.42 USD/kWh PV power generation profile Load profile copper mine Transfer this energy adds significant cost Time

10 Solution: Energy storage Peak shift - battery storage & costs Energy storage significantly increases the cost of generated PV energy Due to large scale production of batteries cost of storage tend to go down but even, if they were cut by half, the cost of generated kwh of PV will by at least doubled- Can we modify the PV energy generation profile?

11 Solution 2?: East/west orientation of bifacial modules W N

12 Bifacial Module Measurement - Setup Bifacial: vertical - azimuth 90 P n1 =255.6 / W STC Bifacial: 30 inclination / azimuth 0 P n2 =255.3 / W STC

13 Bifacial module east/west Measurement results: +8.4% Irradiance Power East/West Power South

14 => With a bifacial module in east/west orientation you would need less peak shift, if your load is in the morning and the evening! What happens in the PV system?

15 PV System bifacial south orientation / d b south Characteristics: Depending on mounting height and albedo higher energy harvest as compared to standard modules Energy peak during midday Shading losses below 5% (Zurich) for f = 0.5

16 PV system bifacial east/west E Characteristics: Broader distribution of the daily energy production Very low chance of soiling Possibility of using alternative, maybe cheaper, mounting systems Chance of further enhancing the energy harvest by use of reflective underground Higher energy harvest as compared to south oriented module but Enhanced shading losses based on the same degree of land utilisation as compared to south orientation S

17 Simulation with PVSyst Simulation parameters 2 standard modules = 1 bifi module Variation of tilt angle and azimut Albedo = 0.2, model Perez Bifi Module simulated b Degree of area utilization / Limitation: No complete row of modules as shading barrier d = Distance between modules S

18 First Simulation results using PVSyst Shading losses resulting from neighbored modules 35% 30% Bifacial east/west orientation Loss in Percent 25% 20% 15% South 37 South 30 10% 5% 0% Degree of area utilization Using a standard utilization factor of 0.5 a relative difference of 10% in shading is observed- but?

19 Simulation with PVSyst f=0.5 PR Monofacial 30 South oriented, Albedo % Monofacial 30 South orientated Albedo % Bifacial East/West orientated 90 Albedo % Bifacial East/West orientated 90 Albedo % Solar _ Input PN 1kW / m A PV System consisting of east/west bifacial modules can be superior to monofacial modules with the same area utilization rate, if a reflective material is positioned in between the modules- this overcompensates the higher shading by far! First measurements with a white foil have shown an increase of power by ~60% (no shading) -5% +25% PR E E AC 2

20 Simulation with PVsyst Power Measured data Simulated data Albedo :45 16:30 14 =>The simulation with PVsyst does not show a good fit to the measured data!

21 Conclusion There is a need for PV power generation profiling in order to adapt to the power load Bifacial modules in east/west orientation are a possible solution if the highest load is in the morning and evening Shading has a severe impact on the energy harvest for PV systems with east/west oriented modules for high area utilization rates. Using a reflective ground in between the modules can have a significant impact on the energy harvest, especially for east/west oriented modules The most economic solution for a certain energy system using PV depends on Energy load distribution Cost for energy storage Area related costs Conditions for soiling Wind loads Reflectivity of the ground Designing a PV system is getting more complex

22 Outlook Simulation models have to be adapted to bifacial modules in order to give better predictions Measurement on real bifacial PV systems with east/west orientation will be made and compared to simulated data using various reflective undergrounds, heights of the modules, area utilization ratios

23 Acknowledgement Many thanks to our friends at the ISC for the good cooperation and for your attention!