The popularity of devices connected to the Internet has been rising steadily in recent years. Nevertheless, in today's market, there are not many solutions for connecting existing devices to the Internet. In this thesis, we will present an overview of available devices and the possibilities of upgrading the existing devices. Next, we will show how we developed a device that allows us to upgrade an existing one without the need to modify it. We will describe the hardware needed for measuring voltage and current, describe the procedure for calculating power consumption and the method of transmitting data to the computer. We will show how to store time series on your computer, process the series for displaying data to the user and describe how to notify the user about patterns of power consumption. We will also look at some of the most popular algorithms for reducing the dimensionality of data and identifying patterns in time series for the purpose of notifying the user.