## 5 Conclusions  
The paper develops a model to examine the impact of bilateral contracts on wholesale electricity markets. It examines different dates, different scenarios concerning the units that participate in the bilateral contracts, and different levels of bilateral contracts. It examines a case where a utility has a dominant position. Therefore, bilateral contracts can be used as a tool for affecting the market. It incorporates dynamic bidding by the market participant, depending on their portfolio in the wholesale and retail market. Using actual data form the Greek power system, the model estimates that bilateral contracts can affect wholesale price, however, the effect is rather limited. The impact is estimated to be higher in the energy mix, where utilities with a dominant position can maximize their production, by committing expensive units in bilateral contracts and leaving their competitive units for the energy exchange. However, the impact again is limited which is justified by the fact that all thermal units are allowed to bid their technical minimum capacity (not meeting bilateral contracts) below their Minimum Average Variable Cost (MAVC), to avoid shut-down costs. This stands as the main tool of a market participants with a dominant position to affect wholesale price and power mix. Besides the fact the role of a market participant with dominant position is evident, the results both in this paper as in a recent one [15], do not reveal its capability to abuse its position, but rather the incapability of power producers to implement a scarcity pricing strategy, due to the availability of capacity, and therefore, to cover their full costs. Considering that the penetration of renewables is expected to increase considerably, due to the rapid reduction in their levelized cost of energy, this research provides insights, in alliance with the recent developments in power utilities in Europe, into not being able to compensate the full cost of their investments in thermal units.  
The results provide insights that could be used by decision makers in European and other energy markets, especially in cases with asymmetrical portfolios in power generation and the existence of market participants with a dominant position. Although the imposition of different levels of cap on the bilateral contracts in case of Greece did not affect the wholesale prices and units' mix considerably, relevant analysis should be undertaken in each power market and for different scenarios, as the market power of participants is linked to the characteristics of each power market, their portfolio, the portfolio of other market participants as well as the evolution of critical factors such as fuel and CO2 prices.  
[PERSON] performed the research and wrote the paper.  
This work has been supported by the Horizon 2020 research project INTERFACE: TSO-DSO-Consumer INTERFACE architecture to provide innovative grid services for an efficient power system (Project Grant Agreement No. 824330).  
The contribution of Dr. [PERSON], senior researcher at the Energy and Environmental Policy Laboratory at the University of Piraeus, in the elaboration of the research is acknowledged.  
The author declares no conflict of interest.