First looks at the new 50W L2-CC constant current driver. This module easily powers 2x4 lights and has 3 current settings. It is a buck topology so the panel DC power supply needs to be above the LED voltage and any wire drop. For commercial projects, use the HEP-1000-54 and set it to 60V for up to 200ft runs.
The driver is 95% efficient, so with typical wire lengths you should reach 88-89% total system efficiency from the AC power source to the LED. This is on par with AC LED fixtures, and that's before power factor losses from AC LEDs without PFC.