The doctoral thesis shows a new method for correcting the feed-in tariffs by calculating the cost-effectiveness ratio of market to non-market model. The market model is based on the feed-in scheme dependent on the market price of the electricity as opposite to existing, pure feed-in, non-market model. Eight different market models are mathematically designed combining different support schemes such as the feed-in tariff price with or without market indexing and the reduced feed-in tariff price above the spot electricity price. For calculating the cost-effectiveness ratio it is applied the method for determining the electricity generation cost and the stochastic processes for simulating the expected spot electricity price. The cost-effectiveness ratio is defined for each market model and different types of renewable sources and cogeneration technologies. Based on calculated cost-effectiveness ratio the feed-in tariff price is corrected, but priory recalculated due to the electricity generation cost. In Croatian case the results indicate the first market model as the most appropriate comparing to other market models as the corrected feed-in tariff prices are the closest to the feed-in tariff prices of the non-market model. With this new method it could be possible to select the most appropriate model in case of other countries with adopted feed-in scheme. Ultimately, this may be the way to select the market model that would be acceptable for all EU Member States. The present position of the European Commission is to ensure compatibility with the internal electricity market with a view to integrating the support schemes in a liberalized electricity market. This doctoral thesis is divided into four chapters. The introductory chapter emphasizes the role and importance of the schemes that support the electricity generated from the renewable sources and cogeneration technologies. A general classification and a brief description of these schemes are given. Besides it gives a short overview of the literature in which authors criticize the application of different support schemes by providing new ideas for their improvements. In the second chapter is carried out a more detailed classification of support schemes and their application in Croatia and the EU countries. The chapter continues with an overview of electricity and heat generation from the renewable sources and cogeneration facilities in Croatia and the EU countries. It gives the shares of electricity and heat generation by different types of fuel, the structure of electricity and heat generation by different types of renewable sources and their shares by electricity and heat generation, separately. Structure of electricity and heat generation from cogeneration facilities are given as well as structure of fuel consumption for electricity and heat cogeneration. At the same time it is shown the electricity and heat generation per capita from the renewable sources and cogeneration facilities. At the end of this chapter it is analyzed the market trends on the busiest European electricity exchanges in the observed period from 2003 to 2012. In the third chapter it is assumed the relation between the total revenues from sales of electricity by applying the market model and the total revenues from sales of electricity by applying the non-market model over the fixed period. This relation is mathematically expressed as the cost-effectiveness ratio. Eight different market models are designed. The cost-effectiveness ratio has been defined for each market model. For this purpose it is used the method for determining the electricity generation cost and the stochastic processes for simulating the expected spot electricity price. First of all the current feed-in tariff price has to be recalculated due to the electricity generation cost. As the market component is a part of every market model it has been applied the following stochastic processes: the geometric Brownian motion, mean reversion and jump diffusion. The expected spot electricity prices will be simulated over the fixed period. Based on the expression for the cost-effectiveness ratio, mathematically is defined the feed-in tariff price correction per each market model. For quicker calculation of the cost-effectiveness ratio it is defined parameters B and m for different renewable sources and cogeneration technologies. These parameters have to be calculated again if a change of input parameters occurs. The fourth chapter provides application of market models and calculates the cost-effectiveness ratio accordingly. The input parameters are given for each type of renewable sources and cogeneration technologies. First, the current guaranteed price has to be recalculated due to the electricity generation cost. After that it follows the simulation of the expected spot electricity price on 12 years as corresponds to the fixed period of Croatian feed-in scheme. As initial price it will be taken the average spot price on the busiest European electricity exchanges in the period between 2003 and 2012. Then it has obtained the results of average cost-effectiveness ratio for different types of renewable sources and cogeneration technologies. They are used to correct the feed-in tariff price based on the current, non-market model. These corrections indicate the first market model as the most appropriate for the Croatian support scheme. At the end of this thesis the market models have been applied to concrete wind power plant VE Ravne-1 located on the island of Pag which is in operation by 2005. The revenues from the electricity sale represent the input data for comparison. The differences between the cost-effectiveness ratio based on actual revenues and the one given by simulation of the expected spot electricity price are insignificant. It shows no financial loss if the market indexed feed-in tariff price had been applied instead of the fixed feed-in tariff price. Even this loss would not have been occurred if the electricity was sold at the spot electricity price and fed into the grid for a half reduced value of the feed-in tariff price. The final chapter provides the concluding observations.