Based on the last example, the COP, or coefficient of performance, is 1. The COP is defined by the amount of heat pumped, in Watts, divided by the power applied to the TEC, also in Watts. It is possible that the COP can be much greater than one for thermoelectric coolers, but this is typically when temperature differences across the device is smaller and the amount of heat pumping is smaller as well. The graphs here show how much heat pumping capacity is left when the temperature difference is larger. So, it is best to oversize the TEC and make the heat exchangers as efficient as possible to minimize the power needed for the TEC.