Price, of course. Prices are expressed in cents/kilowatt hour. Plan types include fixed rates and variable rates. Fixed rates offer consistency throughout the plan term, which can run from six to 36 months. Variable rates can change monthly - they're great when prices go down, but not-so-great when they don't. Finally, if you care about your carbon footprint, you may choose a plan sourced by solar or wind energy.
The local electric company is the utility – that’s the company who owns the infrastructure, including the poles and power lines that deliver electricity to your home. They are who you call if your power goes out or there's an emergency. But in almost every city in Texas, you must choose another company to supply that energy, called a Retail Electric Provider (REP). These REPs, like Spark Energy, allow you to choose electricity plans that offer competitive prices and plans to meet your needs.
Another unwelcome side effect of not knowing your average monthly kWh usage level is that you may end up paying more than you expect. This can occur when a customer inadvertently shops an electric rate based on a higher usage level than they actually use. Electricity suppliers commonly advertise their electric rates associated with the highest (2000 kWh) usage levels since those tend to be the lowest rates.
Short-term prices are impacted the most by weather. Demand due to heating in the winter and cooling in the summer are the main drivers for seasonal price spikes.[121] In 2017, the United States is scheduled to add 13 GW of natural-gas fired generation to its capacity. Additional natural-gas fired capacity is driving down the price of electricity, and increasing demand.

Fixed-rate, long-term (contract) plans provide stability in electricity rates. If market energy costs suddenly trend upward where you live, you can rest assured that you won’t have to pay more out of pocket. However, if you want to switch to a different, lower-cost plan before the end of the contract term, you’ll likely have to pay a cancellation or early termination fee.