Abstract <p>This article considers a possibility of increasing the significance and validity of electric energy price forecasts, a major reference point for making investment decisions and one of the main indicators of national energy security<i>.</i> The expedience of including in the stage-by-stage forecast studies of energy development the estimation of threshold (maximal allowed) electric energy cost for both its producers and users, is validated. A methodical approach and an economic and mathematical model for this estimation are proposed. The acceptable cost of own generation by different groups of users is chosen as a benchmark for estimating thresholds in the area of energy utilization. The share of this so-called distributed generation in the total electric energy production is proposed for inclusion in the number of energy security indicators<i>.</i> Experimental calculation results are provided shedding light on differences in cost thresholds of electric energy generation in integrated power systems and on potential influences of scenario conditions on the economic efficiency and cost of distributed generation<i>.</i></p>