A system comprising: one or more Thermoelectric Coolers, TECs; and an Alternating Current - Direct Current, AC-DC, power conversion system configured to supply power to the one or more TECs for a high efficiency mode of operation and a high heat pumping mode of operation, the AC-DC power conversion system comprising: a first low power AC-DC power converter configured to convert an AC input to a DC output at a first output power level for the high efficiency mode of operation of the one or more TECs, the first output power level corresponding to a high Coefficient of Performance, COP, operation point of the one or more TECs and the first AC-DC power converter having, at the first output power level, an efficiency that is at least 60% of a maximum efficiency of the first AC-DC power converter; characterized in that the AC-DC power conversion system further comprises a second high power AC-DC power converter configured to convert the AC input to a DC output at a second output power level for the high heat pumping mode of operation of the one or more TECs, the second output power level corresponding to a high heat pumping operation point of the one or more TECs and the second AC-DC power converter having, at the second output power level, an efficiency that is at least 60% of a maximum efficiency of the second AC-DC power converter; and a controller configured to: deactivate the first AC-DC power converter when operating in the high heat pumping mode of operation; and deactivate the second AC-DC power converter when operating in the high efficiency mode of operation. one or more Thermoelectric Coolers, TECs; and an Alternating Current - Direct Current, AC-DC, power conversion system configured to supply power to the one or more TECs for a high efficiency mode of operation and a high heat pumping mode of operation, the AC-DC power conversion system comprising: a first low power AC-DC power converter configured to convert an AC input to a DC output at a first output power level for the high efficiency mode of operation of the one or more TECs, the first output power level corresponding to a high Coefficient of Performance, COP, operation point of the one or more TECs and the first AC-DC power converter having, at the first output power level, an efficiency that is at least 60% of a maximum efficiency of the first AC-DC power converter; characterized in that the AC-DC power conversion system further comprises a second high power AC-DC power converter configured to convert the AC input to a DC output at a second output power level for the high heat pumping mode of operation of the one or more TECs, the second output power level corresponding to a high heat pumping operation point of the one or more TECs and the second AC-DC power converter having, at the second output power level, an efficiency that is at least 60% of a maximum efficiency of the second AC-DC power converter; and a controller configured to: deactivate the first AC-DC power converter when operating in the high heat pumping mode of operation; and deactivate the second AC-DC power converter when operating in the high efficiency mode of operation. a first low power AC-DC power converter configured to convert an AC input to a DC output at a first output power level for the high efficiency mode of operation of the one or more TECs, the first output power level corresponding to a high Coefficient of Performance, COP, operation point of the one or more TECs and the first AC-DC power converter having, at the first output power level, an efficiency that is at least 60% of a maximum efficiency of the first AC-DC power converter; characterized in that the AC-DC power conversion system further comprises a second high power AC-DC power converter configured to convert the AC input to a DC output at a second output power level for the high heat pumping mode of operation of the one or more TECs, the second output power level corresponding to a high heat pumping operation point of the one or more TECs and the second AC-DC power converter having, at the second output power level, an efficiency that is at least 60% of a maximum efficiency of the second AC-DC power converter; and a controller configured to: deactivate the first AC-DC power converter when operating in the high heat pumping mode of operation; and deactivate the second AC-DC power converter when operating in the high efficiency mode of operation. deactivate the first AC-DC power converter when operating in the high heat pumping mode of operation; and deactivate the second AC-DC power converter when operating in the high efficiency mode of operation.