Periodic Reporting for period 2 - GOPV (Global Optimization of integrated PhotoVoltaics system for low electricity cost)
Reporting period: 2019-10-01 to 2021-03-31
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
• 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).
• Bifacial silicon heterojunction PV module demonstrating 400 W power, cost of 0.22 €/W and of 35 years lifetime
• 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).
The work was mainly focusing on the development of single components and their characterizations with first outdoor tests conducted to qualify PV modules and trackers at the string level.
For PV module, bifacial Silicon HeteroJunction (HJT) modules were fabricated on an industrial stringer prototype developing Electro Conductive Adhesive (ECA) cell-interconnection technology. Main characteristics are:
• A 144 half-cell (M2 size) architecture with a 6 ribbons interconnection pattern
• A reduced consumption of silicon and silver with 120 m thin cells and only 140mg of ECA per cell.
• An output peak power of 370 W and a cell to module ratio of 97% (from half cells)
The automated stringer prototype was continuously upgraded and its ability to handle up to 8 ribbons of 0.5 mm width with very precise alignment was successfully demonstrated.
A complete process of anti-reflective treatment of solar glass has been developed giving high transmittance gain up to 3.2 % and no optical loss after 1000 of damp heat. The process is ready to be applied on industrial glass lines.
For PV inverter, a 200 kW string inverter based on Flying capacitors topology (beyond the initial target of 166kW) has been designed. The DC/DC and DC/AC power stages have been fabricated, tested separately and finally assembled. The projected efficiency has been assessed at 98.1% but it could be improved in a following step by optimising the switching frequency on the DC/AC stage.
For PV tracker, a set of design tools allowing to optimize the tracker structure whatever the PV plant location and aggressiveness of environment has been developed and applied to optimize the design of the tracker structure for the large-scale ‘integrated PV system’ demonstrator. Apart from the structural elements, all other tracker’s parts including new driving unit, new control and powering system have been developed and tested.
For O&M procedure, a full set of tools was developed to manage the maintenance strategy. It integrates a database of potential failures of HJT modules, a failure detection and diagnosis (FDD) tool, an economic model for PV plant operation and an energy loss model. The FDD tool, the cornerstone of the full set, is combining a mechanistic approach, based on the physics of photovoltaic devices, and data analytic techniques including statistical and machine learning models.
The assembly 1-axis horizontal tracker + bifacial module is being tested on two test sites, the first one devoted on the mechanical performances and the second one the energy producible. First results on the energy producible recorded since 1 year on fixed structures shows a significant gain of 16% for GOPV modules compared to the reference PERC. The test on tracker started later in November 2020 showing first negative gain that starts to become more and more positive from March. From the data collected up to now, a yearly producible gain coming by the combining of bifacial gain and tracking gain above 20% seems possible, with up to 30% for favourable months.
Taking into account the progresses made during the second period, values of LCOE and EPBT have been updated at M31 (October 2020), giving LCOE = 2.09 €ct/kWh and EPBT = 0.73 year, which is already meeting the targeted values for these two general indicators.
For PV module, bifacial Silicon HeteroJunction (HJT) modules were fabricated on an industrial stringer prototype developing Electro Conductive Adhesive (ECA) cell-interconnection technology. Main characteristics are:
• A 144 half-cell (M2 size) architecture with a 6 ribbons interconnection pattern
• A reduced consumption of silicon and silver with 120 m thin cells and only 140mg of ECA per cell.
• An output peak power of 370 W and a cell to module ratio of 97% (from half cells)
The automated stringer prototype was continuously upgraded and its ability to handle up to 8 ribbons of 0.5 mm width with very precise alignment was successfully demonstrated.
A complete process of anti-reflective treatment of solar glass has been developed giving high transmittance gain up to 3.2 % and no optical loss after 1000 of damp heat. The process is ready to be applied on industrial glass lines.
For PV inverter, a 200 kW string inverter based on Flying capacitors topology (beyond the initial target of 166kW) has been designed. The DC/DC and DC/AC power stages have been fabricated, tested separately and finally assembled. The projected efficiency has been assessed at 98.1% but it could be improved in a following step by optimising the switching frequency on the DC/AC stage.
For PV tracker, a set of design tools allowing to optimize the tracker structure whatever the PV plant location and aggressiveness of environment has been developed and applied to optimize the design of the tracker structure for the large-scale ‘integrated PV system’ demonstrator. Apart from the structural elements, all other tracker’s parts including new driving unit, new control and powering system have been developed and tested.
For O&M procedure, a full set of tools was developed to manage the maintenance strategy. It integrates a database of potential failures of HJT modules, a failure detection and diagnosis (FDD) tool, an economic model for PV plant operation and an energy loss model. The FDD tool, the cornerstone of the full set, is combining a mechanistic approach, based on the physics of photovoltaic devices, and data analytic techniques including statistical and machine learning models.
The assembly 1-axis horizontal tracker + bifacial module is being tested on two test sites, the first one devoted on the mechanical performances and the second one the energy producible. First results on the energy producible recorded since 1 year on fixed structures shows a significant gain of 16% for GOPV modules compared to the reference PERC. The test on tracker started later in November 2020 showing first negative gain that starts to become more and more positive from March. From the data collected up to now, a yearly producible gain coming by the combining of bifacial gain and tracking gain above 20% seems possible, with up to 30% for favourable months.
Taking into account the progresses made during the second period, values of LCOE and EPBT have been updated at M31 (October 2020), giving LCOE = 2.09 €ct/kWh and EPBT = 0.73 year, which is already meeting the targeted values for these two general indicators.
New PV components, production tools and processes, software tools with advanced features have been developed or are still in under development:
• An innovative stringer enable to interconnect cells by soldering or gluing using electro-conductive adhesives.
• An industrial process for the coating of solar glass by a high-efficiency, high-durability Anti-Reflective Layer.
• An advanced silicon heterojunction bifacial glass-glass module with reduced silicon and ECA consumption.
• A new horizontal single axis tracker optimized for bifacial modules and made from weathering steel, a lower cost alternative to standard hot dip galvanized steel
• A two stage Flying Capacitors string inverter of 200 kW nominal power using advanced SiC power components
• A full set of tools to manage automatically the fault detection in O&M operations of a PV plant.
All these innovations present a high exploitation potential with commercial exploitation schemes clearly identified. Two of them, the stringer and the tracker are already parts of commercial offers respectively from Mondragon Assembly and Convert. They are all contributing in the reduction of the cost of PV electricity and of the environmental impact offered by the GOPV system, although they can be used independently from each other.
• An innovative stringer enable to interconnect cells by soldering or gluing using electro-conductive adhesives.
• An industrial process for the coating of solar glass by a high-efficiency, high-durability Anti-Reflective Layer.
• An advanced silicon heterojunction bifacial glass-glass module with reduced silicon and ECA consumption.
• A new horizontal single axis tracker optimized for bifacial modules and made from weathering steel, a lower cost alternative to standard hot dip galvanized steel
• A two stage Flying Capacitors string inverter of 200 kW nominal power using advanced SiC power components
• A full set of tools to manage automatically the fault detection in O&M operations of a PV plant.
All these innovations present a high exploitation potential with commercial exploitation schemes clearly identified. Two of them, the stringer and the tracker are already parts of commercial offers respectively from Mondragon Assembly and Convert. They are all contributing in the reduction of the cost of PV electricity and of the environmental impact offered by the GOPV system, although they can be used independently from each other.