The Tank Alert Solar Alarm from SJE-Rhombus is powered by a rechargeable battery via a 12-volt DC, 10-watt solar panel. In full alarm, the unit will run for about 24 hours. Idle use without any solar charging will run for about five days. It features a NEMA 4X indoor/outdoor rated enclosure with integral mounting tabs for convenient installation and features LED indicators to show power on, reverse battery polarity and battery charging. Lithium-ion batteries provide backup power. 888/342-5753; www.sjerhombus.com.