Gujarat Urja Vikas Nigam Ltd., being an instrumentality of the State, is bound by State policy directives and the tariff orders of the Electricity Regulatory Commission and cannot act like a private commercial entity or unilaterally fix tariff in power purchase agreements contrary to the Commission’s mandate; under the statutory scheme of the Electricity Act, the price at which power is procured by a distribution licensee is not a matter of private contract but is to be determined by the Appropriate Commission; tariff order dated 30-1-2010 clearly stipulated that the levelised tariff of Rs. 3.56 per unit applied only to wind energy projects availing accelerated depreciation under the Income-tax Act, 1961, and projects not availing such benefit were entitled to seek project-wise determination of tariff; the discretion given to an assessee to opt for accelerated depreciation before filing its return of income could not be curtailed by the Nigam by fixing a binding tariff in advance in the power purchase agreement; in the absence of any written commitment from the power producers that they would avail accelerated depreciation, the Nigam could not take advantage of its dominant position to bind them to an inapplicable tariff for the entire project life; the plea of estoppel based on execution of power purchase agreements was rejected; orders of the Electricity Commission and the Appellate Tribunal were upheld.