A sustainable method for reclaiming silicon (Si) wafers from an end-of-life photovoltaic module is examined in this paper. A thermal process was employed to remove ethylene vinyl acetate and the back-sheet. We found that a ramp-up rate of 15 °C min⁻¹ and an annealing temperature of 480 °C enabled recovery of the undamaged wafer from the module. An ecofriendly process to remove impurities from the cell surface was developed. We also developed an etching process that precludes the use of hydrofluoric (HF) acid. The method for removing impurities consists of three steps: (1) recovery of the silver (Ag) electrode using nitric acid (HNO₃); (2) mechanical removal of the anti-reflecting coating, emitter layer, and p–n junction simultaneously; and (3) removal of the aluminum (Al) electrode using potassium hydroxide (KOH). The reclaimed wafers showed properties that are almost identical to those of commercial virgin wafers: 180 μm average thickness; 0.5 and 3.7 Ω cm minimum and maximum resistivities, respectively; and 1.69 μs average carrier lifetime. In addition, cells fabricated with the reclaimed wafers showed an efficiency equivalent to that of the initial cells.

In a PV module, the relative humidity (rh) of a front encapsulant is different from that of a backside encapsulant (rh_back). In this study, the effective humidity (rh_eff) in a PV module was investigated to study the effects of moisture variation on the degradation rate (RD). rh_effrepresents uniform humidity in a PV module when it is exposed to certain damp heat conditions. Five types of accelerated tests were conducted to derive the relation between rh_effand rh_back. rh_effshowed a linear relationship with rh_backat constant temperature. Two types of models, namely, Eyring and Peck models, were used for predicting theRDof PV modules, and their results were compared. TheRDof PV modules was thermally activated at 0.49 eV. Furthermore, the temperature and rh_effhistory of PV modules over one year were determined at two locations: Miami (FL, USA) and Phoenix (AZ, USA). The accumulatedRDvalues based on the temperature and rh_effof the modules were calculated by summing the hourly degradation amounts over the time history.

The ideal approach for disposing of end-of-life photovoltaic (PV) modules is recycling. Since it is expected that more than 50 000 t of PV modules will be worn out in 2015, the recycling approach has received significant attention in the last few years. In order to recover Si wafers from degraded solar cells, metal electrodes, anti-reflection coatings, emitter layers, and p–n junctions have to be removed from the cells. In this study, we employed two different chemical etching processes to recover Si wafers from degraded Si solar cells. Each etching process consisted of two steps: (1) first etching carried out using a nitric acid (HNO₃) and hydrofluoric acid (HF) mixture and potassium hydroxide (KOH), (2) second etching carried out using phosphoric acid (H₃PO₄) and a HNO₃ and HF mixture. The first etching process resulted in deep grooves, 36 μm on average, on the front of recycled wafers that rendered the process unsuitable for wafers to be used in solar cell production. Such grooves occurred due to different etching rates of Ag electrodes and silicon nitride (SiN_x). On the other hands, the second etching process did not result in such grooves and produced a recovered Si wafer with a uniform and smooth surface. The recycled wafers obtained by the second etching process showed properties almost identical to those of commercial virgin wafers: thickness, 173 μm; minimum and maximum resistivity, 1.6 and 10 Ω cm, respectively; and average carrier lifetime, 1.785 μs. In addition, P and Al atoms were not detected in the recycled wafers by secondary ion mass spectroscopy.

The corrosion of 62Sn36Pb2Ag solder connections poses serious difficulties for outdoor-exposed photovoltaic (PV) modules, as connection degradation contributes to the increase in series resistance (RS) of PV modules. In this study, we investigated a corrosion mitigation method based on the corrosion mechanism. The effect of added sacrificial metal on the reliability of PV modules was evaluated using the oxidation-reduction (redox) reaction under damp heat (DH) conditions. Experimental results after exposure to DH show that the main reason for the decrease in power was a drop in the module’s fill factor. This drop was attributed to the increase ofRS. The drop in output power of the PV module without added sacrificial metal is greater than that of the sample with sacrificial metal. Electroluminescence and current-voltage mapping analysis also show that the PV module with sacrificial metal experienced less degradation than the sample without sacrificial metal.

A method for enhancing the moisture barrier property of polydimethylsiloxane (PDMS) polymer films is proposed. This is achieved by filling the PDMS free volume with aluminum oxide (AlO_x). To deposit AlO_x inside PDMS, thermal atomic layer deposition (ALD) is employed. The PDMS/AlO_x film thus produced has a 30 nm AlO_x layer on the surface. Its water vapor transmission rate (WVTR) is 5.1 × 10⁻³ g m⁻² d⁻¹ at 45 °C and 65% relative humidity (RH). The activation energy of permeability with the PDMS/AlO_x film for moisture permeation is determined to be 35.5 kJ mol⁻¹. To investigate the moisture barrier capability of the PDMS/AlO_x layer, (FAPbI₃)_0.85(MAPbBr₃)_0.15/spiro-OMeTAD/Au perovskite solar cells are fabricated, and encapsulated by the PDMS/AlO_x film. To minimize the thermal damage to solar cells during ALD, AlO_x deposition is performed at 95 °C. The solar cells exposed to 45 °C-65% RH for 300 h demonstrate less than a 5% drop in the power-conversion efficiency.