Section 94B. No gas or electric company shall, without the approval of the department, hereafter enter into a contract with a company related to it as an affiliated company, as defined in section eighty-five, covering a period in excess of one year, by virtue of which any compensation is to be paid by the said gas or electric company in whole or in part for services rendered by such affiliated company, unless such contract contains a provision subjecting the amount of compensation to be paid thereunder to review and determination by the department in any proceeding brought under section ninety-three or ninety-four. In any such proceeding the department may review and determine the amount of compensation to be thereafter paid under a contract containing such provision for review, and, if it appears that the amount agreed on is excessive, the department may declare the said contract to be terminated forthwith, even if no bad faith be found. Any contract covering a period in excess of one year, subject to approval as aforesaid, and which is not so approved or which does not contain such provision for review, shall be null and void.