It is running a Pi Zero 2 W, and that should run max draw 2.5A@5V (12.5W)[0]. So a Watt hr is using a Watt for an hour. So the question is how many hours continuously you would allow your Pi to run. For 24hrs, that's 24hrs*12.5W = 300Whrs. Just for an estimate, a shargeek is $100 and will give you 24 Whrs[1]. I'm sure you could build your own solution for much better, but assuming since you're asking, I'm assuming this isn't a great option.

So probably a bit more expensive than you're thinking. Especially if you're putting it outside, as you'll need to make the thing more secure from weather. But also the good news is you probably aren't going to actually be pulling those 12.5Ws on your pi. You should probably measure and see.

For solar, I'm not sure especially since you'll need to adjust for your requirements. But there are nice resources that can tell you average capacity, but be careful to note that these will usually show averages and you're going to be significantly affected by seasons in Chicago.

Honestly, I'd get a small battery (like for a phone) and hook it up to an outlet and tuck it away somewhere. That's a much cheaper option. Even if you're "going rogue" with it... the power draw is so little you won't really notice it.

[0] https://www.raspberrypi.com/documentation/computers/getting-...

[1] https://sharge.com/products/shargeek-170

This is not for that kind of setup, this is more of a button you press to get internet when you need it IMHO. It is 1 watt idle, so you need 24Wh to keep it running if there is no sun. On bad short days you might get 5% of solar power. A battery system might lose you 30% on that. Uptime is not primarily an technical issue, it depends on what your goals, skills and needs are.

I actually did something just like this with the second raspberry pi and an offline copy of Wikipedia.

Although I don't know this devices specs I recall being able to reliably power the pi 2b + a 3.5 inch touchscreen with a random 15,000mah solar power Bank from amazon

A 50Ah 12V deep cycle car battery would give you at most 600Wh. This RPi's max draw is 12.5W, but an average draw is 6W is probably reasonable. So that battery alone would get you at most `600 watt-hours / 6 watts = 100 hours` of run time (minus some voltage conversion loss and other imperfections). Then just hook up some solar to charge the battery and assume at least 25% loss. ~70W should probably be enough even for a Chicago winter. The RPi might actually idle at around 1W making it even easier.

All that said, there might be a better solution for you if 99% uptime offline personal Wikipedia is your only goal. And IIAB isn't really optimized for high availability I assume. (just get a local copy of Kiwix on your phone+laptop? Or a cheap dedicated tablet for Kiwix would probably cost less than the battery+solar setup)

I'm running a Raspberry Pi based GNSS receiver from a 26 Ah SLA battery and an 80W panel. Just passed 2 weeks of uptime in a cloudy period of southern hemisphere autumn.

A monte carlo simulation using historical conditions said it had a ~95% chance of no downtime over 3 winter months. A slightly larger battery would bring that up to 99%.

The Pi (3b+), GNSS reciever (u-blox ZED F9P), and Waveshare 7600G 4G modem average about 3.5W idle. The GNSS reciever is about 0.1 - 0.2 W of that. Wifi would be more energy efficient, I imagine.

Is it an RTK base station? If so I'd love to know more about why you set one up.

It's functionally equivalent to an RTK base station (the configuration script I'm using is even called "RTKbase"[0]), but it's being used for researching GPS-based soil moisture retrieval[1]. Basically the GPS signal bounces off the ground and causes an interference pattern that changes based on the wetness of the soil.

There is actually a permanent survey grade GNSS reciever about 200 m away from the u-blox receiver. But the geography around it (too hilly) means it doesn't work for soil moisture retrieval.

[0] https://github.com/Stefal/rtkbase/ [1] https://gnssrefl.readthedocs.io/en/latest/pages/understand.h...

Thanks for the details! I had no idea that estimating soil moisture from the signal was a thing

Are you contributing to Galmon.eu? Sounds like you might be in a useful location.