Except in municipalities which have acquired, expanded, or established a plant under this chapter, the development by a municipality of any small scale power facility, as defined in N.H. Rev. Stat. § 374-D:1, IV shall not be subject to the provisions of this chapter. Nothing in this section shall be construed as exempting municipalities from the provisions of this chapter with respect to the acquisition of a utility plant and equipment if there exists a dispute between the municipality and the utility.