*3.4. Comparing the Cost of Virgin Materials to Recovered Materials*

One final comparison which is important to note is the difference in the private and external costs for virgin materials vs. recovered materials, shown in Figure 6. In Figure 5, we estimate the value of the recovered materials as USD 13.62 but, in Figure 6, the cost of the virgin materials is about USD 90/m2 [37]. There are two main reasons why the virgin material calculation and recovered material calculation are so different from one another. First, the recycling process is not able to recover all the valuable materials that go into making the PV panels, which makes the recovered material payback cost inevitably lower than the input (virgin) cost. Second, the virgin cost estimate includes the machinery and equipment needed for the extraction of materials, while the recovered material cost does not, as recovery does not bare these costs.

**Figure 6.** Virgin material vs. recovered material total cost. The virgin materials' private and external cost data were pulled from our group's earlier study [19], while the recovered materials' data were pulled from the estimations made in this paper.

There is a large difference in the two private cost values in Figure 6 because the cost of purchasing all the materials to construct 1 m<sup>2</sup> of the virgin PV panel is significantly more than the cost of purchasing the materials to recycle these panels. This is due to the fact that many of the metals needed to construct the crystalline silicon panels, such as silver, can be quite expensive. The external cost of using virgin materials is also higher, considering that these materials must be extracted from their original sources, which uses heavy equipment and transportation, while the external cost of recovering the materials comes exclusively from the discharge of chemicals and energy used to break down spent panels. Overall, it is clear that the use of virgin materials is cost-prohibitive as their recycled counterparts have funds of significantly less value. Recovered materials also include the cost savings of selling back these recovered products, which ultimately makes the recycling process a gain cost (or cost positive) for the recycler.
