Electricity rates are different every month based on supply/demand. When it's crazy hot outside in the summer, everyone has their a/c on and electricity rates are high. The opposite happens in March when it's nice out and we have our windows open.
If the 6 month plan in our search results has a high rate it's most likely because you are looking at it around April/May. If you started a 6 month plan in May, it would cover the months May-October....the hottest months of the year. A 12 month plan would include the same prices for those first 6 months but also include the next 6 month's prices, which would bring down the overall average. Either way, you can't go wrong with any of our search results.
Just for your amusement, here is an example of how monthly pricing works in electricity markets.