demonstrated performance in the field for at least 25 years. This suggests that hybrid devices based on c-Si PV technology have a more promising pathway into utility-scale electrical grids. Westover et al. reported a c-Si based hybrid device in which a porous Si electric double-layer capacitor (EDLC) was integrated on the rear surface of a c-Si solar cell after removal of the screen-printed aluminum (Al) rear electrode. [11] However, the large surface area required for charge storage in the porous silicon EDLC inevitably increased the surface recombination, and significantly reduced the open-circuit voltage (V OC ) and therefore the efficiency of the solar cell. [3] In another hybrid device employing the c-Si solar cell, a laser scribed graphene oxide (LSGO) supercapacitor was fabricated on the back of the solar cell. [12] By using an insulation layer between the supercapacitor and the solar cell, the solar cell performance was not degraded. However, this was at the cost of relatively high complexity, as the electrodes of the solar cell and the capacitor were independent. Furthermore, the capacitance may be limited by the thickness of the LSGO electrode and the need to support both electrodes on the rear surface of the solar cell.Both high power and energy densities are desirable for storing PV energy. Fast charge and discharge rates are necessary to quickly respond to the ever-changing sunlight conditions, and effective buffering of PV power requires at least a few minutes of high power discharge when the sunlight is insufficient to meet demand. [4,8] Pseudocapacitive transition metal oxides typically have significantly higher power densities, quicker response times and longer cycle lives than batteries; compared with EDLCs, they have higher energy density due to Faradaic reactions complementing that of double layer electrostatic adsorption. [13,14] For the nanostructured molybdenum oxide (MoO x ) in particular, multiple charge storage mechanisms has been demonstrated, including ion insertion, surface redox pseudocapacitance, and EDL capacitance, [14,15] making it an ideal pseudocapacitive material with high power and energy delivery for PV applications.In this Communication, we report a novel hybrid energy harvesting-storage architecture consisting of an anodic amorphous MoO x (a-MoO x ) pseudocapacitive electrode monolithically integrated on the rear Al electrode of an industrial screen-printed Si solar cell, as shown in Figure 1a. The solar cell and the pseudocapacitor share a common electrode. Compared with previous studies, [11,12] this design has the advantages of integration simplicity and minimum resistive loss of the threeterminal architecture, and avoids degrading the performance of the solar cell. Details of the device fabrication process can The global photovoltaic (PV) power generation in 2015 exceeded 200 GW. [1] Accounting for more than 15% of net supply additions, PV electricity generation is the second-fastest growing source in the world's power sector. [2] However, the direct dependence of PV g...