  Multi-terminal multi-dot devices have been put forward as versatile and
performant setups for thermoelectric energy harvesting at the nanoscale. With a
technique that encompasses and overtakes several of the usual theoretical tools
used in this context, we explore a three-terminal Coulomb-coupled-dot device
for refrigeration purposes. The refrigerator is monitored by either a voltage
or a thermal bias. This comparative study shows that heat driven refrigerator
is much underperforming than the power driven one, due to scarce on-dot charge
fluctuations.
