Ever since I've built my Solar charging station I really wanted to do another project involving solar cells, didn't need to build a solar panel again but I very much enjoyed the idea of a project which is powered by green energy. Last month, a friend had an idea of measuring the water heater temperature using a thermistor which detects the temperature of the pipes going in/out the water heater and broadcasting it to the web. I was excited about this idea, especially because my water heater is on the roof and it was a good excuse for a project powered by the sun. Long story short, I was working on that project for the last month, with some interesting challenges on the way, hardware and software related. The final outcome is on my water heater now, it runs on a very small polymer li-ion battery which is charged by a solar panel.