The past few decades have seen a rapid proliferation of distributed generation sources. These sources can be located at or near load centers and provide benefits which traditional generation may lack. However, distribution systems were not designed to accommodate such power generation sources as they might cause bidirectional power flow and other potential problems and unexpected conditions. This paper investigates the impact of two different types of distributed PV generation sources on a test distribution feeder. A realistic test distribution system has been modeled and a comparative study has been done for two different loading scenarios at a moderate level of PV penetration. The paper further studies the effect of high penetration level of PV generation and points out some problems that might be encountered. The effects of distributed PV generation on voltage regulation, voltage unbalance factor and line losses have been analyzed for the different cases discussed.