I just beefed up the insulation in our ice box, and installed an Isotherm 3701 ASU air cooled cold plate system last fall. Defender had them on a pretty good deal during the Annapolis boat show. Too soon to give any feedback concerning reliability and operation, but I do like the electronics that monitor voltage. It takes advantage of higher voltage by running on high and freezing the plate, when there's excess voltage, due to engine running or solar panel output. At other times, it maintains by running at a lower level, as needed. It should be pretty efficient.