The Department may insert a fundraising letter requesting voluntary contributions to the Fund in utility bills 2 times each year to solicit contributions to the Fund. All public utilities doing business in the State shall cooperate in allowing the Department to insert fundraising solicitation letters in their utility bills. The solicitation letter from the Department must be sized so as to fit into the utility’s standard bill envelope, and must be of sufficiently light weight so as not to cause any increase in postage cost to the utility.