-Anonymous Lakota Artist
Materials above for art-server #solarpoemmachine
Posting from this reddit:
I’ve created a 100% solar powered Rpi web server that runs 24/7 with 0 downtime out in the wild.
(Update: A screen shot of battery voltage plot added to the end)
I wanted to experiment with solar and the idea of a server that is totally off the grid, and totally self contained. This included everything – From power supply to network connectivity, to ensuring weather and other factors will not require constant human intervention. There have been some projects when it comes to solar powered Raspberries, but most of them focus on powering the Rpi for a limited time, or providing a backup solution in the event of power outage. So they were not really sized, nor built for my purpose.
So a brief list of the components:
- Raspberry Pi2
- 16GB Class 10 MicroSD card
- 4G LTE USB modem
- 100Wp MonoCrystalline PV panel
- 52Ah SLA battery
- 10A Solar charge controller with advanced charging (including float charge) and temperature compensation
- INA219 board for voltage monitoring and graphing on the web
- 12-to-5V stepdown regulator
- A well built enclosure for the whole thing to sustain the rain, snow, and the burning 35C during summer
The whole thing costs around $300 (if I recall correctly) and here is how it looks on the inside: http://imgur.com/NOe2ZdW
Here is a picture of the prototype from the outside: http://imgur.com/zKrLMEV
I deployed the box at the top of a building on August 2015 with the intention to power it on and let it be for 6 months without any intervention on my behalf. But as with any experiment things can go wrong. Using another toolbox as a container for the setup, I had failed to seal it well enough. So August almost passed and the rains started coming, I woke up one morning to see the Rpi has not been updating it’s status since the middle of the night. It was flooded. The old controller died and took the INA219 sensor with it. I was also having some issues with the, back than, 3G modem that I was using – It was disconnecting constantly, and even tho I wrote a few scripts to restart the modem, it didn’t do much. The issue was with the ISP. So since I was changing the dead parts, I also changed the modem and the ISP and got 4G speeds. Having a lot of downtime at this point I decided to write the experiment off as a failure and to restart it. I did so on September 1st, powered it up again, in the new shiny sealed box, added more sealant on my own, and got it going.
The solar server survived the autumn and the winter and went through months of less than a single day of clear skies every 10 days or so. It also survived a flood which completely closed a few cities in this part of the country, and a code orange thunderstorm which managed to cut off some communications, some trees too, and killed a few billboards. It did this with zero downtime and only one intervention by me, when the snow cover at nearly 60cm covered the whole setup completely so I had to dig it out of it.
A photo of it, in the snow: http://imgur.com/ShPuaRi
On the sixth month I took it down to review if there are any issues with the components, and they are like brand new. I am very proud and have decided to turn the thing on again soon to offer random blog owners a 100% green wordpress hosting on this platform, most probably for free or at a funny price that would cover the gateway that I use with the 4G modem, and the price of the bandwidth itself. Don’t know yet, but it’s fun.
Hope you enjoy.
EDIT: Nginx+ Php5-FPM + WordPress was what the Pi was running, and it served as a diary of the project.
I could not figure out how to use plot.ly for plotting my recorded battery data because of lack of num2date in their service (or my misunderstanding). I have a lot of data in separate files, each one containing the battery voltage for a given day. If anyone is willing to help in charting all this, I think it would be very helpful in understanding why I chose such a large panel and how important oversizing is in such type of project.
EDIT3: Raw battery data available at http://www.filepup.net/files/Fs8O1463749750.html
EDIT4 xD: What do you do when your experiment is not running and your wife’s car battery dies on you? Well, you charge it for free (obviously completely offtopic): http://imgur.com/7KCJc0g