If you’ve invested in solar panels for your home, you already know that it takes years to recoup that money and see a net benefit. The math is simple: solar panel setups are expensive, and electricity is remarkably cheap. Solar is still worth the investment in the long run, but it’s delayed gratification that will test your patience. That’s why ChristopherD196 wrote up this tutorial that will show you how to build an indicator that notifies you every time you save a penny.
The indicator plugs into a wall outlet, and looks like a Question Mark Block from the Mario universe. An ESP8266 NodeMCU board monitors the solar system, in this case via an Enphase Envoy solar energy management unit. Whenever it sees that a penny’s worth of electricity has been gathered, the indicator lights up and plays the Mario coin sound. When that reaches a dollar, it lights up and plays the Mario 1up sound.
You may be thinking that the electricity needed to run the indicator somewhat negates the energy being gathered by the solar panels, but it’s so minimal that it can pretty much be ignored. The entire device should consume well under 3 watts of electricity. In the US, electricity costs around 12 cents per kWh, so you can run this device for more than a day on a single penny’s worth of electricity. If you want a fun way to get a feel for how much money you’re saving, this device is a great way to do it.