Bifacial PV modules: measurement challenges

Transcription

1 Bifacial PV modules: measurement challenges M. Joanny, G. Razongles, L. Sicot, E. Gerritsen, H. Robin, A. Bettinelli, P. Lefillastre and the CEA team S. Schroder, P. Lay and the ECM Greentechteam Division of Technological Research Solar Technologies Department Laboratory of PhotoVoltaic Modules - maryline.joanny@cea.fr 1

2 OUTLINE - Different measurements possible: 1) Indoor one face 2) Indoor bifacial 3) Outdoor bifacial Series resistance + on-site parameters 2

3 First consideration: STC measurement Indoor STC 1 Front side measurement Isc front, Pmax front, Voc front 2 Back side measurement Isc back, Pmax back, Voc back, bifaciality Isc 3

4 First consideration: STC measurement Indoor STC 1 Front side measurement Isc front, Pmax front, Voc front 2 Back side measurement Isc back, Pmax back, Voc back, bifaciality Isc Let sdrawa linearidealpmaxwiththe front and back irradiance Pmax STClinear = Pmax front + Pmax back x G back 1000 W/m² It isa preliminaryapproachthatdoesnot consider: 1) the impact of the series resistance on Wp evaluation 2) the impact of the on-site parameters on Wp evaluation Nota :G back = irradianceon back side(w/m²) monofacial 4

5 OUTLINE 1) Indoor one face 2) Indoor bifacial 3) Outdoor bifacial Series resistance + on-site parameters 5

6 CEA INES bifacial indoor characterisation set up Aluminium mirror self-monitoring of irradiance with Isc Mesh filters gives: G back = 230 W/m² or G back = 470W/m² or G back = 1000 W/m² Mask Mesh filter 4 cells module 6

7 Performance evaluation Pmax STClinear for 16,7Wp STC 3BB module 88% bifacial (Pmax) monofacial 7

8 Performance evaluation Pmax STClinear for 16,7Wp STC 3BB module 88% bifacial (Pmax) Pmax bifacialmeasurement monofacial Bifacial measurement and STC linear calculation give different values for Pmax 8

9 Performance evaluation Pmax STClinear for 16,7Wp STC 3BB module 88% bifacial (Pmax) Pmax bifacialmeasurement Pmax = 2,5% monofacial Calculation of : Pmax = Pmax STClinear -Pmax bifacialmeas. Pmax bifacialmeas. for 3 module architectures 3 bus ½ cells, 4 bus and 3 bus: 9

10 Performance evaluation Pmax = Pmax STClinear -Pmax bifacialmeas. Pmax bifacialmeas. Highest Pmax isobtainedfor highestg back Lowest Pmax isfor 3 bus ½ cellsand is< 1% for G back < 500 W/m², but ishigherfor the othersmodules Need to integrate FF consideration 10

11 Evolution of FF with total irradiance FF module FF 1000 W/m² Decrease of module FF with increase of irradiance FF slopesdependson celland module seriesresistance(3 bus ½ cellsperformsthe best) Same FF slope for STC measurement and bifacial measurement 11 Indoor measurementat 3 values of G front (700, 1000 and 1200 W/m²) givesconfident FF slope Total

12 Extrapolation from indoor one face measurements at 700, 1000 and 1200 W/m² G back Voc extrap. from700/1000/1200 Pmax extrap. from700/1000/1200 = Pmax front x (1 + bifaciality Isc x ) x x 1000 W/m² Voc front 1) Introduction FF extrap. from700/1000/1200 FF front Integration Workshop of PV FF Modultechnik and Voc consideration Cologne gives better 12 Wp evaluation

13 OUTLINE 1) Indoor one face 2) Indoor bifacial 3) Outdoor bifacial Series resistance + on-site parameters 13

14 CEA INES bifacial outdoor characterisation set up CEA INES, Chambéry, France 2 bifacial modules with black screen for reference use 2 bifacial modules workingwithhigh albedo RENOLIT ALKORBRIGHT synthetic roofing membrane Bifacial optimized mounting structure no shadowing CEA bifacial modules: n-type, glass-glass, TPO Apolhya Solar from 14

15 Bifacial outdoor measurement Energyyieldbifacial modules / reference modules G Front (W/m²) Energy Yield (kwh/kwc) G Front (W/m²) Reference modules Outdoor monitoring over 13 days (J1 to J13, on April 2015) 15

16 Bifacial outdoor measurement Reference modules Monitoring April 21st

17 Bifacial outdoor measurement Needto belinkedalso to on-site parameters Reference modules On-site parameters to be considered: Temperature Monitoring April 21st

18 Bifacial outdoor C (with Tre correction) Needto belinkedalso to on-site parameters Reference module On-site parameters to be considered: Monitoring April 21st 2015 Temperature Weather(diffuse or reflective) and G front -assessedby energyyieldresults Albedo 18

19 Bifacial outdoor measurement Assymetry on back side contribution θ= 17 4 modules West North Est Reference modules South On-site parameters to be considered: Monitoring April 21st 2015 Temperature Weather(diffuse or reflective) and G front -assessedby energyyieldresults Albedo Geometrical parameters 19

20 Summary and conclusion Series resistance considered On-site parameters considered Wp Ease of implementation If flash test at 700 for instance W/m² are addedto 1000 W/m² Depends on the equation used If series resistance are considered Albedo considered Geometry/weather not considered The different approaches are complementary and will help building the equation, which is under STC international discussion, for calculating the expected Pmax of bifacial modules, taking into account the series resistance and the on-site parameters. 20

21 Thankyoufor your attention References: M.Joanny, B.Soria et al., 2 nd BifiPV Workshop, Chambéry (France, 2014) Alternative Energies and Atomic Energy Commission INES RDI Savoie Technolac BP avenue du Lac Léman F Le Bourget-du-Lac - FRANCE T. +33 (0) maryline.joanny@cea.fr Technological Research Division Department of Solar Technologies Photovoltaïc Modules Division Public establishment with commercial and industrial character RCS Paris B : This document may be distributed to other third parties as the contractors. It must be distributed unchanged and in its entirety and include the issuer s attribution and credit. This corresponds to the type of licence aa aaaaaaa defined by However, recipients are requested to exercise sound judgement when redistributing the document. 21