Design and prototyping of a thermal energy meter for solar applications

Abstract

In 2009, the EU Renewable Energy Directive 2009/28/EC had for the first time recognised solar thermal systems as contributing towards the renewable energy target of EU Member States, rather than just saving energy. This was a major step change in its perception towards this technology, which was consolidated by the updated directive (EU) 2018/2001 that specifically requested Member States to promote the use of renewable heating systems in buildings. However, quite often, solar heating systems do not come with an accompanying thermal energy meter. This implies that the user is not able to quantify or report the thermal energy savings. Consequently, Member States often resort to estimates when it comes to reporting their annual thermal renewable energy generation to the EU. This project aims at addressing these challenges by designing, building and testing a low-cost, reliable, versatile, and accurate thermal energy meter that can easily fit to any solar heating system with the scope of monitoring and storing performance data, as well as controlling the use of backup electric heaters with the intention of optimising the use of solar energy, without compromising the availability of hot water. Moreover, the device shall include features to alert the user of any potential malfunctions of the SWH, which can all be accessed through a user-friendly web-based interface. The requirements and means to monitor the performance of a SWH to a high degree of accuracy were explored, and using appropriate hardware and software configurations, a prototype was produced, calibrated and tested on a typical domestic thermosiphon solar heating system. After extensive testing and fine-tuning, it was confirmed that the monitoring device functioned as intended with stable operation. By the end of the project, the prototype has passed all tests and fulfilled all the aims of the project, for monitoring the system, storing and presenting data, controlling solar heater operation, reporting malfunctions and making it all accessible through any network-connected device. Given that the market does not offer a similar device at a reasonable price, the product has the potential of being further developed to make it market ready. To that end, future endeavours will be made to patent it and to apply for seed funding for further development towards commercialisation.