The motivation for this master thesis is my work in the field of investment analysis in the renewable energy sector. If looking at a wind power plant in operation for sale multiple risk factors come in mind of different sources. The core objective of current work was to find a systematic approach to collect and condense these risk factors, finally leading into a rating number, an important instrument for an equity investor to take an investment decision. The method of approach consisted of literature study to come up to definitions of the main topics and to get an overview over the status of risk models already published it the wind power sector. A top down approach was chosen, deriving the main risk drivers from a conceptional level, leading into a description of specific risks, leading into a matrix, displaying only one aggregated number with the needs of the addressee in mind. Data were chosen from a literary analysis. The result is on the one side a custom-made model weighting and displaying managed and not managed risks, ready to be used for quick checks, on the other side the following conclusion was made: risk factors are linked directly to the technology but the interpretation of legal framework, economic circumstances and soft factors play truly an important role which depends on the risk awareness of the assessor. Generally said, factors influencing the revenues or the capital costs are most threatening in the case of a wind power investment and need most attention.