Delivering 16 V DC From A Solar Panel, Continued
When the solar-powered PC is idling, the special M2-ATX power supply achieves a stunning efficiency level of 92.37%. If we load up the CPU or the graphics subsystem, efficiency sinks to 88.4%. Internal power consumption in the PSU itself varies from 5 W at idle up to 14.2 W under load.
These measurements bolstered our decision to go with a 16-Volt DC solution. Using conventional A/C power, the best PSUs achieve efficiency values of 87% under optimal conditions. This approach not only does away with energy losses inherent in two-stage transformation of output, it also does better at dealing with DC input than the best conventional PSUs do with A/C input. This PSU is built in the USA, and costs $80-90 - well-known mini-ITX vendor Logic Supply and automobile PC vendor SolarPC are good sources for this part in North America.
Back side of the PSU circuit board
Power Supply Connectors and Components
- Power LED
- To motherboard on/off switch
- To external power on/off switch
- ATX connector (20-pin)
- P4-12V power connector
- User jumper settings
- Positive voltage input (battery)
- Ignition (switched battery, positive)
- Negative voltage input (battery)
- Amplifier control via remote on/off
- Configuration for on/off timer settings
In cases where the power supply has to work at peak output for any length of time, the manufacturer recommends installing a cooling fan. We chose the Papst 512 F/2 using a 5 V adapter, which caused the fan to draw only 160 mW.