4 ms·

I started out like the author of the blog post with a 60Watt panel and a cheap non-mppt solar controller. My balcony orientation was shit and that didn’t work o

I started out like the author of the blog post with a 60Watt panel and a cheap non-mppt solar controller. My balcony orientation was shit and that didn’t work out. Since then I upgraded “quite a bit”… The challenge is more difficult than it seems. A raspberry pi 4b does ~3.4 watt idle so that’s 84 watt-hour per day. This may not sound like a lot, but for battery-powered devices it quite a bit. Microcontrollers can run months on that amount of energy, but they aren’t as convenient as the Pi. The 12v 12ah battery used, contains 144 watt hour. Only enough to cover less than two full days with little to no sunlight. The 50 watt panel is already small, but the non-mppt controller makes it even more inefficient. With good sunlight, the panel can easily run the pi and charge the battery during daytime. The “real” challenge is to keep the Pi online during days of overcast weather. A 150 watt panel may only do 4-8 watt under those circumstances and that’s not enough. But I always love these projects none the less.

dragontamer 3y ago
I know Rasp. Pi is all the rage these days, but if I were to make a solar-server, it'd be off of Beaglebone Black instead. * Beaglebone Black uses slightly less power and is slower than Rasp. Pi. Lower power is a big benefit however. * Beaglebone has the "Programmable Realtime Unit" (a microcontroller-like hard-realtime subsystem with GPIO pins). * These PRU subsystems can probably (???) be utilized for the battery-state-of-charge and possibly even provide a software-control for mppt solar chargers. Theoretically of course, but... I have to imagine that a Cortex M4 has enough MHz to handle these kinds of calculations. * If not, the Beaglebone Black has a built in ADC that could be used as the basis of power calculations. Worst case, add in a proper uC to handle power / build my own MPTT / Battery charger.
- tiagod 3y ago
  At least on MCUs, being slower can counter-act the lower active power, as you'll take longer to do whatever you want to do and go back to deep sleep. I'd like to know if this also happens with these SBCs, or if they even have any aggressive power saving features that can be employed.
  - dragontamer 3y ago
    I'm not sure about the specific power modes of Rasp Pi except I hear they're barebones and kinda bad. But in any case, servers cannot sleep. Only clients can. Maybe the software architecture of this SolarPi should be rethought. Or maybe perpetual power needs to be more carefully figured out here so that the Pi can truly function as a server.
puzzlingcaptcha 3y ago
3.4W at idle _is_ a lot - this is x64 territory. Many laptops use less (with the screen on!). Also this is a drum I beat a lot but RPi i just not great for server use (no ARMv8 crypto extensions for example). I am sure you could find a viable alternative that sits under 2W at idle. Rock Pi S maybe? Not sure if it is still available.
- yomlica8 3y ago
  Doesn't the pi zero use much less? To me the zero is the more interesting of the pis. The Pi4 is more performant but I felt its power usage was to high for ultra low power and at that point I'd probably just use x86. But it seems like a popular product.

dragontamer 3y ago

I know Rasp. Pi is all the rage these days, but if I were to make a solar-server, it'd be off of Beaglebone Black instead. * Beaglebone Black uses slightly less power and is slower than Rasp. Pi. Lower power is a big benefit however. * Beaglebone has the "Programmable Realtime Unit" (a microcontroller-like hard-realtime subsystem with GPIO pins). * These PRU subsystems can probably (???) be utilized for the battery-state-of-charge and possibly even provide a software-control for mppt solar chargers. Theoretically of course, but... I have to imagine that a Cortex M4 has enough MHz to handle these kinds of calculations. * If not, the Beaglebone Black has a built in ADC that could be used as the basis of power calculations. Worst case, add in a proper uC to handle power / build my own MPTT / Battery charger.

tiagod 3y ago
At least on MCUs, being slower can counter-act the lower active power, as you'll take longer to do whatever you want to do and go back to deep sleep. I'd like to know if this also happens with these SBCs, or if they even have any aggressive power saving features that can be employed.
- dragontamer 3y ago
  I'm not sure about the specific power modes of Rasp Pi except I hear they're barebones and kinda bad. But in any case, servers cannot sleep. Only clients can. Maybe the software architecture of this SolarPi should be rethought. Or maybe perpetual power needs to be more carefully figured out here so that the Pi can truly function as a server.

puzzlingcaptcha 3y ago

3.4W at idle _is_ a lot - this is x64 territory. Many laptops use less (with the screen on!). Also this is a drum I beat a lot but RPi i just not great for server use (no ARMv8 crypto extensions for example). I am sure you could find a viable alternative that sits under 2W at idle. Rock Pi S maybe? Not sure if it is still available.

yomlica8 3y ago
Doesn't the pi zero use much less? To me the zero is the more interesting of the pis. The Pi4 is more performant but I felt its power usage was to high for ultra low power and at that point I'd probably just use x86. But it seems like a popular product.