Energy (Electric) Costs

I know this has been posted a number of times before and I wish I would have paid more attention and even more so, I wish I had a better memory. I sort of remember that there was about 3 charging tiers when it comes to electrical costs. Thinking of possibly buying a casa in or around Zihua and I am looking at an old energy bill where I think the cost is $635/kW and $198/kWH. Are these the numbers that one can decrease after several months of using less energy? Any other help (in explaining the bill) would be greatly appreciated. Gracias.