*2.2. Private Cost*

P.CInv is important to discuss in the private cost assessment of PV recycling because, before being able to make a turn of profit on PV recycling, an infrastructure must be set up. This can require significant amounts of money as many innovative PV recycling processes warrant new, specialized equipment. Another issue is that the profitability of investments related to the construction of PV recycling facilities and equipment is guaranteed only by the management of great amounts of wastes [23]. In small or lab-scale operations, high investment costs may mean that a facility never turns a profit. This paper draws its investment costs from processes required in the FRELP method, in which insight into the steps of the PV recycling techniques was given. The costs of equipment were taken from manufacturers' websites [27,28]. In order to complete the recycling processes described in the paper the costs of purchasing, these technologies must be taken into account. Although these are traditionally one-time costs, the lifetime of machinery, yearly mass produced, and number of panels in our functional unit were considered to represent the investment cost of PV relative to the other process costs on a 1 m<sup>2</sup> basis. Table S2 in the Supplementary Information tables is a collection of the supplies and costs of the equipment needed for c-Si investment for the given recycling process.

The transportation costs were found by utilizing Latunussa data on distance traveled (km), averaging diesel cost, and estimating average semi-truck fuel efficiency. This can be found in Supplementary Information Table S3.

#### *2.3. External Cost*

The environmental externality cost (E.C) data were estimated by multiplying the emissions from the recycling process with the damage cost per mass of emissions

$$\text{E.C} = \text{Emission (kg)} \times \text{Damage Cost} \,(\text{USD/kg}).\tag{5}$$

Emission data were taken directly from Latunussa's paper. The PV recycling pollutant numbers were multiplied by the found environmental externality multipliers to determine the approximate cost of the process' impact per material. The data for these externality values comes from four sources [23,29–32] The Supplementary Information tables include all externality tables for the recycling of PV panels (Tables S5–S7). Below are the impact categories used in this paper and their corresponding damage cost values. Within the four papers from which this data was pulled, some variation occurred between values. For simplicity in this paper, the damage cost number listed below was pulled from its most recent publicized representation. For example, if a value for CED was found in three of the four papers, the value used in this paper would be pulled from the most recently published work. The nature of the gaps between the values can be investigated in their original work, but, in short, different LCA metrics have different environmental impacts which cause distinct environmental damage. Some of the metrics with higher damage costs are those which have impacts that society deems more disruptive and unsafe than others.
