PV Panels
From Open Source Ecology
How They are Made
How is Silicon Produced
- Carbothermal reduction - Si02 is heated with Carbon (charcoal) in an arc furnace to produce metallurgical grade (impure) silicon
- This silicon can be drawn into a round billet from a melt
- Metallurgical grade silicon is purified to solar grade silicon (not as pure as semiconductor grade) by zone refining in vaccuum [1]
- This is an induction heater traveling up a billet of silicon
- Vaccuum sucks out light impurities
- Heavy impurities are travel up the melt zone as melt zone travels up the billet
Phosphorus
- Phosphine - [2] - dopant. 40 l cylinder - $700 - [3]. 0.2 ppm is required for doping PV. [4]
- If a PV panel, 285W, weighs 19 kg and maybe 1.5 kg silicon - [5] - then .2 ppm -> then 0.3 mg of phosphine per panel. If a bottle of phosphine contains 10 kg phosphine, then one bottle is sufficient for - 30,000,000 panels! Thus, phosphine costs per panel are negligible - 0.002 cent per panel. This may be reduced for inefficiency of diffusion - but still likely to be way under 1 cent per panel.
Boron
- Diborane gas - used in doping. [7]. $1400 per tank - [8]
- $500/kg - [9]
- Borax - 25 cents/lb
Sourcing
- Wanxiang 230 Watt 60 Cells Poly Silver Frame UL. 16 of these would be 3680W. [10]. Company - [11]. Panel specs - [12]. The site shows panels as low as 20 cents. Is there a USA source at similar cost?
