Energy metering and data logging with remote access are nothing new, the Internet of Things is here and such devices are becoming more commonplace every day. So what makes Wattmon stand apart when compared to other similar devices?
The foremost two things that most people seem to like are the flexibility and the interoperability, so I will focus a little on these two topics.
Bringing flexibility to an embedded device is challenging for any developer - it helps a lot when product specifications are clearly defined beforehand, especially when working with limited resources and processing power such as the Microchip PIC32 processor used in the Wattmon. Even before beginning work on this project I could imagine many different scenarios where the device could be used, such as for home automation, data logging solar charging, battery management, pump control, weather stations... And more!
Wattmon separates the firmware kernel and operating system from the application - the firmware resides in internal flash and implements the uPHP (micro-PHP) scripting language with a subset of PHP's functionality. The application - or package as I refer to it - is a set of scripts that run off the microsd card and perform any function required. The wattmonsolar package handles data logging and battery management for solar setups, and the wattmon water setup handles a 3 phase bore well pump and several booster pumps, making it the perfect tool to manage remote water tank setups.
All these scripts are open source, and anyone can extend and modify them to suit their requirements - this is nothing new either since Linux is open source too, but the combination of a small embedded device capable of running custom scripts with ready made open source packages for energy monitoring is less common. The raspberry pi brings flexibility and power, but it is still not easy for a layman to manage, and it isn't packaged into a final product.
Many larger solar companies have some form of data logging or computer connector on their devices. Charge controllers may have information about the state of charge and voltage, as well as kWh generated. Inverters may have some outputs about load or performance. All of these usually connect to a proprietary software or hardware device from the same brand.
Consolidating this data together is not easy, and usually requires an expensive add on device. Wattmon simply plugs into your cable network and doesn't care which brand is managing your energy generation or load, as long as it has the full picture of all energy flowing through the battery. This means it is no problem to change brand, and you can save money on those expensive monitors!