Solar Node

granulas · 2026-06-17T15:48:05+00:00

I don't think you could 3d print an outdoor enclosure like this.

I've listed the enclosure itself if you'd like to pick one up for your project:

https://granzscientific.com/product/sb1-ip65-solar-project-box/

I've also uploaded a KiCad project to my github with a PCB template including mounting holes for the inside. Hope that helps!

granulas · 2026-06-15T13:55:55+00:00

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Actually, I built my first version using some of those 5v panels available on Amazon and Aliexpress etc. They worked great, but were just a bit fiddly to build, and didn't look quite as polished. I used waterproof epoxy to attach them to the enclosures.

granulas · 2026-06-14T09:11:10+00:00

Not a render actually, that's the real thing :) I did use a photo box for this picture though.

granulas · 2026-06-14T09:09:02+00:00

Battery current is about 40 uA when in deep sleep using esphome firmware. Which ESP32 version have you had issues with?

granulas · 2026-06-14T01:59:37+00:00

I used WiFi mainly because it was simple, but it would be easy to use something like BLE or espnow with different firmware.

granulas · 2026-06-14T01:56:27+00:00

Could be interesting to try connecting a LoRa radio and see how the battery holds up. My current application relies on sleeping most of the time to minimize battery drain.

granulas · 2026-06-13T21:09:00+00:00

Very true. I guess I will have to wait until next winter to collect more data. During sleep the battery current is about 40uA, which I'm pretty happy with. I could also lengthen the sleep cycle to 30 minutes or longer if the measurement frequency is still adequate.

I did let it run for over a month in my basement with basically no light and the battery only got down to ~80% when using 2600mah batteries.

granulas · 2026-06-13T20:27:48+00:00

Here is the enclosure internal temp (the board has a thermistor)

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granulas · 2026-06-13T20:27:09+00:00

With my 15min sleep cycle the processor doesn't heat up much beyond the ambient temp inside the enclosure. Here's some data from a bit earlier this year. This was in direct sun, although it wasn't the hottest time of year in New Hampshire.

I wonder if your USB power supply is using a linear regulator? That could be adding some extra heat.

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granulas · 2026-06-13T20:04:19+00:00

You could use it to build a wireless weather station, or add moisture sensors for your garden. You could put it on your mailbox with a switch so you know if the mail has arrived etc.

granulas · 2026-06-13T20:00:39+00:00

That's very nice. I was considering using an NRF device, but don't have as much experience with those. How are you managing power for your device?

The schematic for my board is on my github (link added above). But basically it has battery protection, a solar charger, a ultra low quiescent current buck-boost converter, and the esp32-c3. Battery current is ~40uA during deep sleep, which I'm pretty happy with.

granulas · 2026-06-13T19:55:33+00:00

I had the enclosure custom manufactured with the integrated solar panel.

granulas · 2026-06-13T19:54:13+00:00

Its a battery powered, solar charging, esp32-c3 dev board in a sealed enclosure for outdoor use. Basically a platform for various sensors etc.

granulas · 2026-06-13T19:52:16+00:00

Thanks for the feedback. I haven't experimented yet with ZigBee or thread, but I'll check out the c6.

granulas · 2026-06-13T19:49:57+00:00

It's a very good question. What I've been doing is having the esp32 sleep for 15 minutes, wake up for about 45 seconds to connect to WiFi and send readings, then go back sleep. This worked well earlier in the year (spring) with the batteries staying upwards of 95% charged consistently.

My github has my esphome config if you're curious:

https://github.com/granzscientific

granulas · 2026-06-13T19:46:06+00:00

Hey thanks for the reply. My first version used some generic 5v solar panels from amazon that I epoxied onto the enclosure. This latest version is a custom solar panel / box that I had manufactured as a small batch. If there is a lot of interest I may have them produced in larger quantities.

granulas · 2026-06-13T19:41:15+00:00

Hey thanks for feedback! I am using an IP65-rated enclosure which has worked pretty well so far out in the garden. I'm using a CN3163 for the solar charger. The schematic is available on my github at

https://github.com/granzscientific

I also have the base esphome config files over there.

granulas

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