Most commercially available photovoltaic solar cells are crystalline silicon cells. However, in indoor environments, the efficiency of Si-cells is poor. Typically, the light intensity under artificial lighting conditions is less than 10 W/m² as compared to 100-1000 W/m² under outdoor conditions. Moreover, the spectrum is different from the outdoor solar spectrum and there is more diffuse than direct light. Taken into account the predicted cheaper costs for the production of organic solar cells, a possible niche market for organic PV can be indoor applications. In this article, we study the properties and suitability of several bulk heterojunction organic solar cells (with distinct different absorption spectra) for different indoor conditions. We simulate different light environments and use a silicon solar cell as reference. Depending on the required power for the indoor device, we determine minimum requirements for the environment (light intensity and indoor spectrum) and for the organic solar cell (absorption spectrum and surface area). In this way we determine the appropriateness and conditions for a competitive indoor use of organic solar cells.