Methods for scalable output voltage and encapsulation of organic photovoltaic cells are addressed in this paper. To obtain scalable output voltages, integrated photovoltaic modules comprised of a bulk heterojunction of poly(3- hexylthiophene) (P3HT) and a soluble C 70 derivative, [6,6]-phenyl C 71 butyric acid methyl ester (PCBM-70), were fabricated. Power conversion efficiency of individual P3HT/PCBM-70 cells was estimated to be 4.1 % for AM1.5 G illumination. Modules of one to four cells connected in series produced open-circuit voltages V OC that linearly depend on the number of cells N as V OC = N × 0.621 V with a nearly constant short-circuit current of 1.4 ± 0.1 mA. Separately, shelf lifetimes of more than one year were achieved for pentacene/C 60 solar cells by encapsulation with a 200-nm-thick layer of Al 2 O 3 deposited by atomic layer deposition (ALD). In addition, the ALD process improved the open-circuit voltage and power conversion efficiency of the solar cells by thermal annealing that occurs during the process.