Hello to the best forum! I have a new tutorial up and live on How to Create a Solar Powered Raspberry Pi.
If you want to take your Raspberry Pi out into the deep wild, far away from the electricity grid, one of the best ways to power your system is Solar Panels. There are many ways to create a solar-powered Raspberry PI, but this is absolutely the easiest way. A Raspberry Pi Board, a PiJuice Solar Panel, a PiJuice HAT and a Micro-USB to USB Cord is all you need to get your project up and running. Connect them all together and just like that you can harness the energy of the Sun! PiJuice Settings also means you can create automatic safe shut down and restarts based on charge percentage. I even created a Solar Powered Weather Station and put it to the test. So with Earth receiving a daily bombardment of 173000 petawatts of power you deserve to use a little slice of it.
Would this setup be enough to keep a raspberry (4 model B) running 24/7 in a place without electricity? or how long would you think it would be running?
By keeping the pi juice panels exposed to the sun, would that always be charging the battery in the pi HAT? (as long as there’s good sun)
Theoretically, it may be able to. It’s essentially a potential energy question. It will depend on how much power your Pi draws over a given period of time compared against the Wh of your battery on the PiJuice (Tim’s calculation for a Pi Zero was 12000mAh for ~67 Hours idling and throughout the day your panel would need to kick out enough Wh to both power the Pi and charge the battery to capacity with the excess).
To get an accurate estimate of how long the Pi can remain powered (or continuously) you need to know how efficiently the PiJuice charges your battery, the power supplied from your solar panel, and for how much of the day that power gets kicked out.
Using CRON jobs and other tricks you should be able to improve the longevity by scheduling periods of time where the Pi performs some function you would like rather than running continuously and use the PiJuice:
Tim also made another tutorial specifically on saving power on the Pi:
But as he said in the tutorial, if for some reason the panel doesn’t get exposed to sufficient sunlight for an extended period of time due to cloud cover or storms eventually the battery will run dead so this isn’t a highly reliable system for continuous power generation but should be applicable for most hobbyist projects.
I’ll let @Tim know about your question when I see him next and see what he thinks
Thank you for the information! We are using a Rpi 4 B, which I understand consumes a lot of power. The usage would be mostly idling, until a person comes near and connects through wi-fi to it, in order to browse a collection of educational contents. We are building “hotspots” where people whitout internet access can browse educational contents by connecting through wi-fi to the Rpi.
Apart from disabling features, maybe it would be possible to configure the pi so that it shuts down during the night hours (9pm to 9am) where it’s unlikely to have any users?
Absolutely awesome project. Because Raspberry Pi 4 Model B are very energy-hungry and what you want for this project can be achieved by a Raspberry Pi Zero or a lower energy Raspberry Pi so I would recommend using one of them instead.
Also, to make sure it runs 24/7 you will need to use a larger battery than the one that comes with the PiJuice UPS. This website can give good idea of discharge time when performing different tasks PiJuice Battery Discharge Time Calculator • Pi Supply.
The PiJuice UPS will allow you to schedule shut down and wake up cycles for the Raspberry Pi so that can definitely be achieved. Learn more on that here https://core-electronics.com.au/tutorials/ups-with-raspberry-pi-4.html.
Also make sure to have all the electronics waterproof
Thanks Tim! I will check out all your recommendations.
If you were looking to keep something as small as possible while still being able to access a webserver I would also take a look at using an ESP32 (They have onboard WiFi and Bluetooth) and can be programmed in micropython (a lighter weight remix of the full version). They have a lots less processing power but can still give access to any data from sensors if thats what you were going for, uploading videos from the Pi → a phone is definitely best handled by a Pi (Single board computer or SBC)…
Just expanding on Liam’s point, you’d have to make sure your content was really lean. I used an ESP8266 (the predecessor of the ESP32) as a WiFi repeater once (impractical, but that’s a story for another time), and the data transfer rate was pretty poor for the data-hungry big sites on the web these days. Could you give an idea of the sort of content you’re trying to push through these hotspots?
Cool project and I’m keen to see it come to life!
I’m planning to build a ADS-B receiver to situate in a remote location. This will require a solar power solution. Ideally it would be running 24/7 with minimal maintenance visits.
I have a Raspberry Pi 3B+ set aside for the project, Huawei E3372 4G dongle and of course a ADS-B dongle.
The PiJuice seems to be a great way to manage the solar side of things. The number calculations do my head in though. Would you be able to advise of a suitable battery/panel combination that would keep things running with plenty of excess?
Pi power consumption is generally very low (I measured a Pi running headless at about 4W at the wall, sometimes less), but it can vary based on how much work it does.
I’d say the first step is to set up your Pi and ADS-B receiver in a way you can measure the current draw. USB testers like this one are good for getting an average load, but you’ll need a multimeter or something fancier to catch small spikes.
Once you’ve got an idea of how much power it draws, you can estimate the size of battery and solar panel you need. A rule of thumb for roof solar (may not apply here) is you get about 4Wh for each watt of solar panel you have. You might want to factor in being able to survive a few cloudy days with minimal sun, plus a bit of overhead for losses in the PiJuice and a bit of wiggle room.
Thanks James. I’ll put it together, measure and go from there. Cheers!