Operation and Maintenance (O&M) tasks are becoming increasingly important in the asset management of photovoltaic projects. However, there is insufficient evidence to analyse in depth its influence on the energy and economic performance of such systems. The wide range of O&M annual expenditures (OPEX) and the lack of standardization further complicate the proliferation of specialized studies. This paper analyses the influence of OPEX on the performance and viability of a utility-scale photovoltaic tracking plant based on real data. After a description of the O&M costs incurred to maximise photovoltaic performance, a first result shows that a percentage decrease in annual OPEX does not necessarily imply the same trend in energy losses. Although this electricity decrease may jeopardise the viability of the project, the economic outlook of this study shows that high quality O&M not always improves the Levelised Cost of Electricity or the annual liquid asset of such investment. Finally, it shows real evidence of the influence of promotion policies on the viability of photovoltaic projects, taking Spain as an example, where it is more profitable to abandon the preventive maintenance of a photovoltaic plant than to invest in O&M and only undertake corrective O&M in limit situations