Real time monitoring systems in photovoltaic (PV) power generation are very important and urgent in some cases. This paper proposes a real time monitoring system for solar panel using the Atmega 2560 arduino which is connected with voltage sensor, current sensor and temperature sensor. The Arduino ATMega 2560 also connects with the Wifi module as a connection to the smartphone to display the measurements of current, voltage and power of solar panel and ambient temperatures through the Blynk app. This system is tested for seven days starting at 08.00 am to 04.00 pm. The designed monitoring system has a good degree of accuracy with an average error rate of monitoring results of solar panel output value below 10%. Monitoring the performance of solar panels using a smartphone-based microcontroller can be done in real time. The monitoring system can be developed for the larger PV systems.