My flat has a prepayment energy meter.
Sometimes I forget to check how much money we have and the power goes out, forcing me to walk to the nearest open PayPoint location at inconvenient times.

I wanted a way to automate these checks.

The Raspberry Pi B+ enclosed emails me a photo of the money we have left

I had an unused Raspberry Pi B+, camera module (REV 1.3), and a USB Wi-Fi dongle. With these I could take a photo of the amount left and email myself a photo every day at a specified time.

It turned out to be easy.
The most time consuming bit was experimenting with raspistill options to produce the best photo for the dark cabinet it’s enclosed in.

Amount of money left on our prepaid electricity meter

Amount of money left on our prepaid electricity meter

As you can see the photo is not amazing. However, considering it was taken in a dark cabinet I’m happy with the result.

Full instructions here:

Next, I want to use Optical Character Recognition (OCR) to detect the amount in the photo.
I could then take readings every 5 minutes, save that to a database and produce a graph of the times when we use the most electricity.