The resource of stored elastic energy is evaluated with the help of a symmetric model of orthogonal joining of crystals, which makes it possible to compute the number of generations of martensite crystals and the fraction of the formed martensite (the integral one and for any of the generations). It is shown that the resource of the stored elastic energy for twinned crystals may grow by an order of magnitude as compared to the variant when twins are absent; the increase with respect to the starting values of the resource amounts to almost ten orders of magnitude.