This bachelors thesis deals with photovoltaic technology and economic evaluation of used technology equipment. The first part describes the technology for extraction of power from photovoltaic sources - transformer 22/0,4kV and its basic parts. Then there is the calculation of the amount of openings for cooling the transformer according to ČSN 33 3240. The second part focuses on the description of the major part of the photovoltaic plant. Here are divided solar panels on the material from which they are produced and the type of installation in the field. Next is describe the types of inverters, their principles and functions. The last part compares the different types of transformers and operating costs over the lifetime of plants (20 years...