This paper presents the alarm system of solar panels operation. The system consists of sensors
and transmitter device and receiver device. In the first device, the data as temperature, humidity,
intensity, voltage and current are measured by sensors and electronic circuits. All data are sent to a
microcontroller, in this paper use Arduino MEGA, for adjust the data to be more accurate. Then all data
are transmitted to the cloud storage by wifi shield. For the receiver device, we develop the application
for the android operating system on mobile devices. This application is designed to alert when all data
are in the condition, show the data in real time by the graph, back up the data per day by email automatic
sending and connect to more sensors and transmitter devices. The test results of the alert system are the
system can alert by the application on mobile devices within 2 minutes after the event is not normal,
show the data of temperature, humidity, ultraviolet, voltage and current in real time, send all data to the
user by email every day and connect to sensors and transmitter devices up to 5 devices without making
an application lose functionally.