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High frequency PECVD for silicon thin film deposition

Sun Well Solar uses Plasma Enhanced Chemical Vapor Deposition (PECVD) systems to perform various silicon films deposition. Instead of conventionally-employed 13.56 MHz RF plasma-excitation frequency, our PECVD systems are all equipped with 40.68MHz VHF generators, leading to higher deposition rate, better film quality and hence excellent module competitiveness.

LPCVD for in-house TCO deposition

Sun Well Solar uses Low Pressure Chemical Vapor Deposition (LPCVD) technology for zinc oxide (ZnO) deposition onto glass. In comparison with other transparent conductive oxide (TCO) glass technologies, such as APCVD-SnO2, sputtered ZnO and sputtered ITO, the LPCVD-grown ZnO has advantages listed below:
(1) bare glass can be purchased locally for superior cost competitiveness
(2) the production capability of in-house TCO glass provides the flexibility in layer optimization to improve energy conversion efficiency.
(3) LPCVD enables growth of ZnO-film on the glass surface with naturally textured morphology (as shown above), which causes much more light trapping in cells for better utilization of a solar spectrum.
(4) compared with aluminum doped ZnO-film by sputtering, LPCVD deposited ZnO-film doped with boron shows low absorption at high wavelengths; thus allowing more light can come to silicon films for being absorbed.

Module Technology Difference

We produce modules with both TCO-coated front and back contacts, as shown in the above figure. Amorphous silicon exhibits higher light absorption ability than that for mono-crystalline silicon. The unit cost of output power can hence be lowered due to its better nominal watt power performance by using our PV modules. Moreover, our see-through and opaque modules can be fabricated without and with a white reflection layer, respectively. Referring to the see-through modules, some of the competitors use laser to scribe away the back metallic contact for a wider opening to allow more light penetration. Compared to this, our see through modules can exhibit a superior output power due to no loss of the active area.
Taking a closer look at the cross view of the PV modules, one can see the difference between our products and the competitors. The advantage of our see-through PV module is light can pass through for the whole panel.Therefore it is not difficult to see the laser scribing for opening at back contact and reflector, used for the competitors, will result in the active area loss and finally reduction of output power.

PRODUCTION

Proven technology for amorph and microcrystalline PV absorbers

High speed laser scribing for all three patterns

Device contacting and contact curing