AWARDSSHORTLIST
handling in production more challenging and reduce the yield of solar cell lines due to increased wafer and cell breakage. In-line wafer breakage reduces equipment throughput as down time.
Millions of dollars are lost due to microcracks. It causes cell and wafer breakage, it reduces cell and module efficiency, it leads to quality claims. In production environment RUV has proven to be able to solve 90% of the problems.
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The Resonance Ultrasonic Vibrations technique was developed for in-line non- destructive crack detection in full-size silicon wafers and solar cells. The RUV methodology relies on deviation of the resonance frequency response curve measured on a wafer with peripheral or bulk millimeter-length crack and on identical non-cracked wafers. The silicon wafer is a large contributor to the overall cost of the solar cell. In addition, the silicon raw material price has roughly doubled in the last two years due to a worldwide shortage of the polycrystalline silicon feedstock. To compensate for the feedstock shortage, solar Si wafers are sliced thinner with thicknesses down to 80-200 microns.
Wafer areas have also been increased to reduce overall production costs. These technological trends make wafer
The RUV technology allows (1) rejection of unstable Si wafers after ingot cutting before they are introduced into cell processing, (2) identification of wafers with mechanical defects (such as cracks) during production to avoid their in-line breakage, (3) detection of cracked cells before they are laminated into modules to avoid panel efficiency reduction and product return from the field. By using a RUV wafer, solar cell and module manufacturers will improve their production yield and reduce costs. They also can analyze machine efficiency regarding crack initiation as well as differences in wafer and cell quality between vendors.
Through a frequency sweep (20 -100 kHz) the RUV method enables crack detection with simple criteria for wafer or cell rejection. A crack introduced into Si wafer alters the RUV peak parameters: amplitude, bandwidth and peak position. This is illustrated in the figure below
This is for two identical Cz-Si wafers. Specifically, the crack in the wafer shows the following features: (1) a frequency shift of the peak position; (2) an increase of the bandwidth, and (3) a reduction of the amplitude. Therefore the RUV approach is essentially based on fast measurement and analyses of a specific resonance peak and rejection of the wafer if peak characteristics deviate from the normal non-cracked wafers. The sensitivity of the system, which refers to length of the cracks, is adjustable to the needs of the user.
The rejecting method is based on a statistical approach. In several tests the accuracy of this method was between 91 - 95%. That means that the breakage caused by cracked wafers or cells is reduced by at least a factor of 10. RUV Systems can also provide examples and cases showing concrete results.
Inline waste reduction (breakage, wasted modules) Efficiency improvement Reduction of quality claims.
Energy Usage Enabling Award
Enecsys Ltd
Enecsys solar PV, grid connected micro-inverter
The Enecsys micro-inverter converts DC to AC at each solar module, eliminating the need for a central string inverter. A solar PV system based on Enecsys micro-inverters will have improved energy harvest and therefore cut the cost of harvested power by up to 20% over the lifetime of the installation compared with a conventional system using string inverters.
The Enecsys solar micro-inverter is designed for high reliability and has a life expectancy of at least 25 years, thereby matching the life of solar modules to which they are directly connected.
The exceptional reliability of the Enecsys micro-inverter is achieved through a patented design that embodies three key attributes: a rugged topology, a component set based on high temperature rating and reliability, and a unique patented energy control technique.
The Enecsys micro-inverter is first to use thin film capacitors instead of less reliable electrolytic capacitors and eliminates the use of opto-couplers, which are also known to have relatively poor reliability. In addition, PV systems using Enecsys micro-inverters are simpler to plan, easier to install and intrinsically safer.
It is the only micro-inverter specified to maintain full performance from -40 degrees C to +85 degrees C, and achieves peak efficiency of 94.1% over
www.solar-pv-management.com Issue V 2010
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