Typically, the LED's are driven using a current driver circuit. The driver circuit regulates current.(Unfortunately, many of such design failed in real life environment-you may want to check what happen when such a driver is overloaded/overheated) The power supply regulates the voltage. A lot of commercially available power supplies have variable input AC from 90VAC to 240VAC. The primary side (AC) is rectified and converted to DC using, most commonly, a pulse width modulation technique(I am not aware of PWM used to rectify ac to dc before-please email me how this is done.) Variation in line voltages does not have significant effect on output voltages since the control loop is usually fairly tight. That being said, the current drivers to the LED's take the stable, DC output voltage and supplies current to the actual LED's. The current is regulated via pulse width modulation but, the maximum current is accounted for by a current setting resistor on the driver boards.
The overheating of the PFO Solaris cards is not due to overpowering the diodes. The issue stems from the lack of thermal grease used during initial manufacture and during repair of the LED strips. The securing screws that holds the LED boards also can back out due to vibration in the fixture. The air gaps caused by the above two scenario's causes overheating and failure of the LED's. (I made LED bars upto 90W without any fans and very little metal to act as heat sink and survived over 2 years-the couple ones having issues are either salt creep or plainly the circuit over driving them when one circuit got disconnected for whatever reason.)
In early versions of the Solaris unit, PFO used thermal grease as the diode slug interface to the circuit cards. The grease wasn't alway applied evenly causing diode overheating. Later versions of the light strips had better adhesion to the circuit cards with both solder and thermal epoxy.(Because the lense used in Solaris can pulled the leds out. In the market, most LED lights use ONLY soldering to adhere the bulbs-I personally tried on couple Solaris bought to service, simply by touching the lense, the LEDs legs and soldering will be stressed to a dangerous level) Those boards seem to be highly reliable when proper thermal grease spread is achieved at the circuit card to heatsink interface.
The actual LED data produced by the lighting manufacturer's shows very good reliability. The reliability improvements of the later Soloris is due a host of changes including, different material used, power supplied used, mounting technique and may be also the controller/driver electronics which I have not had the chance to investigate.
Food for thought, Mark
