Even with increased volume, today's processing and equipment technology is not able to provide a manufacturing cost lower than 2 ECU/Wp. The main goal of the MENHIR programme is to demonstrate the feasibility of a 1.4 ECU/Wp manufacturing cost for cells based on large (125x100mm2), thin, multicrystalline silicon wafers. This goal shall be pursued through the demonstration of the feasibility of high volume and high speed processing in electromagnetic cold crucible continuous casting and in solar cell and module activities including handling equipment. Casting speeds ranging from 1 to 4 mm/min and solar cell and module processes able to treat one cell every one or two seconds are the main targets.
Up to now 120 mm diameter billets with growth speeds of 1mm/min have been achieved. The development of the electromagnetic casting prototype will be pursued with a square cross section cold crucible able to deliver 125 x 125 mm2 wafers. The following points shall be addressed in detail: silicon feed, melting inside the cold crucible, control of the solid/liquid interface, control of the cooling conditions and development of numerical models coupling heat transfer and induction phenomena. Test castings will be realized at EPM-Madylam of Grenoble in collaboration with ALD vacuum technologies of Erlensee for system design, specification, and process control.
Faster solar cell and module processes are to be investigated and tested by IMEC of Leuven, IES of Madrid and PHOTOWATT of Bourgoin concerning anti-reflecting surface treatments, front and back junction formation, metallic contact deposition, soldering and cell encapsulation in conjunction with reliability tests performed at ESTI of Ispra. The ECOTECH grouping of four research and analysis laboratories is in charge of cast material and cell characterisation. The selected processes will be tested, demonstrated at the pilot level and cost analysed by PHOTOWATT and SOLTECH.
Expected Achievements and Exploitation
The expected outputs of this project are:
- Development of the EMC caster prototype and process control - Multicrystalline silicon billets to make large and thin wafers - Technical specifications of the electromagnetic caster
- Faster processes on large multicrystalline silicon solar cells and module activities.
- 14% to 15% conversion efficiency on 125 x 125 mm2
Industrialisation of pilot processes achieving the above targets will reduce costs for 125 x 125mm2 wafers to 1.25 ECU/Wp while reducing capital investments for a 30 Mwp plant by a factor of four.
Funding SchemeCSC - Cost-sharing contracts
21020 Ispra - Varese