Notes • George's Notes • Updated Monday, November 18th 2024

SolarPi

A place to stash some random notes as I can continue to tinker with my SolarPi project.

I'm appreciating that this idle weekend project seems to have no bottom, if I let it!

The PiSugar battery module was a good find. It gave me power regulation in a perfect form-factor for the Raspberry Pi Zero at a good price. I currently have the thing monitoring the current battery level and detecting whether or not it thinks its charging. All useful data to have for this project.

I've also got it set to safely shut itself down it power gets below 10%. It will then try to wake itself up at sunrise the next day.

Figuring that part out was fun and led me down a tiny rabbithole trying to understand the math to determine sunrise relative to your current latitude and longitude. The actual math is, unsurprisingly, involved. I settled on a script that employs the Python sunrise package. Even if it's a little less accurate than making a call out to an API, I liked the idea of calculating this on-device to avoid a probably more energy-expensive network call over the wifi.

A fun I got the Pi to update the sunrise time once a day, but daylight saving's time goes into effect tomorrow. The time it's giving me right now is one hour after all the online resources I can see (~7:30am versus 6:30am). I think this discrepancy is just because of daylight savings kicking in tomorrow and it'll work itself out. I guess I'll know more tomorrow!

The big problem I'm grappling with now is that my solar panel is a bit under-powered for my current setup. I'm facing mostly north, maybe a little northeast. We're headed into winter and the amount of direct sunlight I get on my terrace is reduced. In the direct light the current panel can do everything I need, albeit seemingly barely. A higher wattage panel might be in my future, but they start to get rather large quickly once you enter 100W territory... that's probably overkill. Maybe I should look at the 60W panels.

There is also a matter of where to put the thing. The morning light is more consistent, but that's a more difficult edge to place the panel at an angle. The westward facing part I could put on the adjacent roof... though part of my wonders what my neighbors will think.

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