This Solar-Powered Weather Station Features an E Ink Screen
An E Ink screen was the perfect choice for Ricardo Sappia’s solar-powered weather station
E ink (also called ePaper) displays seem almost magical, because they only require power when refreshing the content of the screen. If they’re showing a static image, they don’t draw any power at all. Combine that with incredible contrast and the technology is very desirable for certain applications—particularly low-power devices that don’t update often. That made an E Ink screen the perfect choice for Ricardo Sappia’s solar-powered weather station.
E Ink screens have two major disadvantages. The first is that they’re slow to refresh, with some models taking a second or longer to update the entire screen. The second is that most models are monochrome. There are some that can display a handful of colors, but they have even slower refresh rates than their black-and-white cousins. In this case, neither of those disadvantages are practical concerns. This device displays detailed information about the day’s weather conditions and that information doesn’t need to change often. The only exception is the clock in the corner that needs to update once per minute, but that only requires a partial refresh.
Because Sappia chose an E Ink screen, this weather station consumes very little power and so it can get all of the energy it needs from the sun. Sappia designed the device to sit against a window where a small solar panel on the back of the enclosure can receive good exposure to sunlight. During daylight hours, that recharges a small LiPo battery that keeps the device going through the night. An ESP32 development board pulls weather information from the internet and shows that on the E Ink screen, going into a power-saving deep sleep mode between updates.
This particular E Ink display is a 2.13” tri-color model from Wemos with a resolution of 250×122. It can display white, black, and red pixels. Sappia designed a comprehensive GUI that displays the time, date, moon state, sunrise time, sunset time, temperature highs and lows throughout the day, wind speed and direction, and cloud cover conditions. Most of that is black and white, but Sappia used red in a few places (such as to represent the sun).
All of those components fit in a tidy 3D-printed enclosure that Sappia can place on a window frame.