The ELR 10000 4U series are regenerative programmable electronic DC loads in a 19-inch 4U rack enclosure, sinking 30 kW per unit at voltages 0–80 V up to 0–2000 V and currents 0–40 A up to 0–1000 A. Instead of converting the absorbed energy into heat, they feed it back to the local grid with efficiency up to 96%, reducing energy and cooling costs in burn-in, end-of-line and R&D testing. An autoranging input stage, CV/CC/CP/CR modes, an integrated function generator, battery test mode and a solar inverter (MPPT) test mode make the ELR 10000 suited to testing batteries, fuel cells, DC sources, chargers and power electronics.