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How to recycle solar panels?
11-09
As we all know, solar photovoltaic modules have a warranty life of 25 years, and can even be extended to 30 years. Thirty years is a long time, but not eternal life. In fact, the first large-scale use of photovoltaic systems, has gradually reached the age of aging retirement. What to do after the failure of the module? Next, the recycling of solar panels is discussed.
Reuse the battery inside the solar panel. Most of the time, the failed components are due to the failure of the back plate, the discoloration of the adhesive film and the broken glass, but the battery itself is still strong. The battery is the valuable part of the component. The natural idea is to recycle the battery for reuse. However, to remove the components without damaging the battery inside, it is very difficult to tear off the back plate, or soak hydrochloric acid to remove EVA adhesive film (time-consuming, damaging metal electricity); Either organic solvent removes EVA (more time-consuming); Either ultrasonic wave exceeds EVA (consuming electricity); Either heat pyrolyze EVA (the battery is basically wasted). Ideal is very plump, the reality is very skinny, want to recycle performance is not affected by the battery, basically can not do!
Reuse the silicon chips inside the solar panels. Since the battery cannot be recovered, we will settle for second best and reuse the valuable part of the battery-the silicon chip. After recycling, the silicon wafer is made into a battery again. This requires various chemical methods to remove silicon nitride, metal electricity, emission and back field. Specific collocation may be hydrofluoric acid, nitric acid, sodium hydroxide, potassium hydroxide and so on. The reality has once again become a bony one-people are not as good as heaven. With the development of technology and the requirement of cost reduction, the thickness of silicon wafers has dropped from 300 microns to below 200 microns and will continue to decrease. The result is that silicon wafers simply cannot withstand the ordeal of chemical treatment-crushing! The road was blocked again.
Reuse solar-grade silicon. Since the silicon chips cannot be recovered, let's take another step back and recycle solar-grade silicon. Although it is said that the single crystal or ingot will be pulled again and sliced, at least we have saved the purification steps! This program is the mainstream direction today. Let it be broken. If it is broken, we will pull the crystal or cast the ingot again. Like the previous method, front emission and back field are not required. Using sodium hydroxide to quickly remove the surface layer of several microns, and then using square resistance to detect whether the emission and back field are completely removed, can be made into usable solar grade silicon.