One of those things that took a long time to register in my aging brain. Our DSL/wifi modem has a 12vdc wall wart power supply. This is well suited for a 12vdc solar system; also for a battery backup to keep the modem active for telephone/wifi access in a power outage. In power outages our DSL phone service and wifi access also goes down. Hooking up a 12vdc battery to the modem is an easy and quick fix to keep these active during the outage. The current draw for our modem on 12vdc is 360ma.