Diversity of geography, fuel, and economy, Regulatory support, Plant operating efficiency, and Continuing cost reduction program. Parent company's debt increases debt service burden for its utilities, and Purchased power adds $1 billion debt equivalent to consolidated balance sheet. The rating on utility holding company Xcel Energy Inc. is based on the consolidated credit profile of Xcel and its and its vertically integrated utility subsidiaries, Northern States Power Co. (NSP-Minnesota), Northern States Power Wisconsin (NSP-Wisconsin), Public Service Co. of Colorado, and Southwestern Public Service Co. The rating on Minneapolis, Minn.-based Xcel reflects the utilities' solid business profile, which incorporates the generally supportive state regulation that governs each utility's rates, the relatively low-cost power supply and overall fuel diversity, and the diverse