Inspired by the lander #Philae on comet 67P we started a while back working on low-power projects assuming that we do have only solar power to recharge batteries and might need to sleep during a period of time to wake up on a given event.
Update: the project has now proven to run solely of solar power for 3 days/nights, that might sound not that much, but bear in mind we are running an power hungry wifi module just from a 200mAh LiPo and harvesting solar power from a tiny 0.5W solar panel … as a comparison the used LiPo would ran out of power without any tricks in a single hour. Read about the tricks used:
The ESP8266 Thing from SparkFun is a nice board – but first we want to get it ready for NodeMCU so we can code it in LUA language without the need of an Arduino(TM) IDE. Further more we use LUA to control the sleep mode (switching off not used components) and wake up for work – isn’t it like real life 😉 With that we can run the ESP8266 Thing and equivalent ESP8226 (e.g. Adafruit) independent from the power grid just by solar power! Btw. we just add a solar panel and a LiPo – *no* expensive solar charger!