Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - GOPV (Global Optimization of integrated PhotoVoltaics system for low electricity cost)

Teaser

GOPV (Global Optimization of integrated PV system for low electricity cost) is targeting two major objectives. The first one is to lower the price of PV electricity in order to improve its competitiveness and to accelerate its development in Europe. An electricity cost of 0.02...

Summary

GOPV (Global Optimization of integrated PV system for low electricity cost) is targeting two major objectives. The first one is to lower the price of PV electricity in order to improve its competitiveness and to accelerate its development in Europe. An electricity cost of 0.02 €/kWh is targeted for large PV plants located in south Europe from 2022. The second objective is to bring techno-economic competitiveness to European PV industry who is struggling to survive in a context of ultra-domination of the PV field by Chinese players. Both objectives can be fulfilled simultaneously through the developments of advanced PV components, PV module, tracker, inverter, as well as advanced operation & maintenance procedures that altogether will lead to a PV system with lower CAPEX, higher yearly producible, increased lifetime and lower OPEX. Main characteristics targeted for PV components are:
• Bifacial silicon heterojunction PV module demonstrating 400 W power, cost of 0.22 €/W and of 35 years lifetime
• Current source string inverter with 99% efficiency, cost of 0.05€/W and 20 years lifetime
• 1 axis tracker made of low cost structural materials, cost of 0.11 €/W and 35 years lifetime
• Automatic fault detection and diagnosis tool allowing energy availability of 99.5% and O&M cost of 0.01 €/W/year
To achieve these challenging targets covering a large part of the PV value chain (except PV cells that are being developed in parallel in the H2020 project Ampere), GOPV merges the forces of five leading European industrial companies (Enel Green Power, Mondragon Assembly, Convert Italia, Refu, GXC coatings) and five internationally recognized R&D institutes (CEA, Tecnalia, Leitat, RSE, EPFL).

Work performed

The first period of 18 months, is focusing on the development of individual PV components, whose main characteristics have been defined to optimize the performance and cost at the overall PV system level, and O&M procedure.

For PV module, the bifacial Silicon HeteroJunction (SHJ) technology that offers high-energy throughput thanks to high efficiency under real outdoor operating conditions and best in class bifaciality ratio has been selected. In order to develop further advanced features such as increased power efficiency, lower raw material consumption (particularly costly metals) and increased lifetime, developments are focusing on:
• Low stress, low temperature cell interconnection process and associated fully automated manufacturing tool based on electro-conductive adhesives (ECA). This conducted to the manufacturing of a new stringer enable to perform cell interconnection by gluing using ECA as demonstrated by the fabrication of a first series of 6 kW of strings of 12 bifacial SHJ cells.
• Cost effective, high efficiency and long lasting anti-reflective coating deposited by low cost process. This conducted to the manufacturing of a first series of 20 large area glasses of 2x1 m² that exhibit an average gain of 2.5% in light transmission.
• Lean module design with selected encapsulation material and lamination process. This conducted to the manufacturing of 6 kW of glass-glass modules with average power efficiency of 371 W.

For PV inverter, the current source topology has been extensively studied and a current source inverter of 125 kVA has been fully designed. This design fully satisfies the technical targets with a simulated peak efficiency as high as 99.3%. However its estimated cost of production was exceeding the targeted 0.05 €/W, mainly due to the high cost of needed 1700V SiC components. Therefore an alternative flying capacitor topology compatible with the use of more common and less expensive 1200V SiC components is under investigation. First cost assessment below 0.04 €/W is in line with GOPV target.

For PV tracker, developments are focusing on:
• The design of a new tracker adapted to bifacial modules and optimized to lower the wind load, in order to reduce as much as possible the overall quantity of structural elements and the size of the driving system.
• The substitution of the common hot dip galvanized steel structural elements by lower cost weathering steel (WS) and lightweight corrosion-free glass fiber reinforced polymer (GFRP).
• The fabrication of 5 tracker prototypes; 3 of WS only and 2 of mixed WS-GFRP ; both types will be installed and tested on the field for the next period.

For O&M procedure, developments are focusing on:
• The analysis of potential failures occurring in large PV installations, their occurrence rate, their effect on the PV production and their curing procedure.
• The economic model of PV plant operation, constructed from above data, to define optimal O&M schemes, taking into account the balance between energy yield maximization and O&M costs reduction.
• The failure detection and diagnosis models in order to detect abnormal performance of PV components before impacting PV plant producible.

GOPV technological developments are continuously evaluated, regarding the levelized cost of electricity (LCOE) and their environmental impact, and compared to the reference scenario (same PV plant with classical PV technologies located in south Spain). Updated estimations of LCOE and greenhouse gas emission, taking into account latest specifications of GOPV tracker, inverter and module, are respectively 2.44 c€/kWh and 12.1 g CO2 eq. / kWh for GOPV plant, compared to 3,785 c€/kWh and 20 g CO2 eq. / kWh for the reference The energy payback time for the GOPV plant is also reduced to 0.9 year well below the 1.3 year calculated for the reference. Such reduced values are validating our approach even if the initial target of 2 c€/kWh is not reached so far.

Final results

New PV components with advanced features are under development. During this first period:
• An innovative stringer enable to perform cell interconnection by soldering and by gluing using electro-conductive adhesives has been developed by MASS. This new tool has been designed to process full and half-cells and is able to handle up to 8 interconnection ribbons. This is a key element towards the fabrication of very high efficiency modules, particularly when heterojunction technology is considered. Adjustments at the machine level to improve further reliability, throughput, breakage rate, etc and to fine tune the interconnection process of heterojunction cells will be the subject of the next period.
• The scale-up of the AR coating was realized. GXC has developed internally the capacity to perform large area coating on glasses up to 2m by 1m. In the next period, the chemical modification of the coating to add anti-soiling properties and the tuning of the sintering step for its integration in the glass production lines will be investigated.
• Advanced silicon heterojunction bifacial glass-glass modules have been made by CEA, integrating the anti-reflective coating technology from GXC and the multi-ribbon gluing interconnection technology from MASS as well as carefully selected encapsulant. This conducted to front efficiency up to 375W (CTM = 94 %) and bifaciality ratio of 89%.
• A new tracker optimized for bifacial modules, made from lower cost material alternative to standard hot dip galvanized steel has been designed, and first prototypes fabricated by CONVERT.
• An optimal scenario for O&M, based on preventive maintenance of PV plant, leading to an estimated cost of 0.0103 €/W/year

Website & more info

More info: https://gopvproject.eu.