Poly(ethylene terephthalate) (PET) was depolymerized by aminolysis technique using ethylene diamine by aminolysis method and product form is alpha, omega-amino-oligo(ethylene terephthalamide). Depolymerization was carried by several techniques, such as solar energy, UV irradiation, microwave irradiation, and ultrasound irradiation. Ultrasonication was carried out at 20 and 40 kHz. UV irradiation was carried by varying the power source as 20 and 40 W and by varying the temperature. Microwave irradiation was done by keeping the power source as 300 W constant and reaction was carried out at three different temperatures, i.e. 100, 110 and 120 AC, and then by keeping the temperature constant at 110 AC, the power was varied as 500 and 700 W. Depolymerization with solar energy was done by just keeping all the ingredients in the air tight container under solar radiation. By UV irradiation, microwave irradiation and solar energy, none of the PET flakes remain unreacted. The time required for microwave is similar to 6 to 7 min, for UV irradiation it is 24 h and for solar energy it is 8 days. It is observed that among all the studied technique solar energy is the most eco-friendly one. Hence, the product obtained from it was characterized by DSC, FTIR, H-1-NMR analysis.