In addition to the disallowances set forth in this subsection, the commission may disallow any other costs of the unit or units which the commission deems appropriate. For the purposes of this section, a rebuttable presumption is created that a unit or units or portion thereof shall be determined to be excess unless found to be needed to meet the utility's customer demand plus a reasonable reserve margin in the test year or the year following the test year, or, if it is a base load unit, it is also found to produce annual economic benefits which will exceed the total annual cost of the plant during the test year or within a reasonable period following the test year.
An adjustment shall be made under this subsection regardless of whether or not the new base load unit had been in service during or at the end of the test year used in the proceeding.
66 Pa.C.S. § 1323