Issues when powering thingy:91 from solar panel

[Jonathan E]

Hi!

I am trying to power the thingy:91 from solar panels and have some issues with the thingy:91 restarting when the solar panel receives a medium amount of light. The solar panel charges the device properly in full sun and does not interfere with the device when there is no sun. However, it starts rebooting when there is some light. I assume that this is because the USB solar panel outputs a voltage lower than 5V, but high enough that the regulators turn on so that the nrf9160 is supplied with too low voltage. I have tried with multiple USB-solar panels which most often are used to charge surveillance cameras.

Do you have any tips on how to run the thingy:91 from a USB solar panel properly?

Best regards,

Jonathan

[Kenneth]

Hello,

I would likely have measured the VDD on startup, and made sure it's stable over a few seconds and (sufficient high) before starting to do something useful, also periodically measure VDD and enter power down immediately if VDD start dropping below operating conditions:
https://docs.nordicsemi.com/bundle/ps_nrf9160/page/recommended_op_conditions.html 

Kenneth

[RichM]

I would also like to know this outcome. It seems like the PMIC is designed to handle this situation. I also tested with PPK2 and everything continues to work. Having an inexpensive solar option (like the ones available) would be a huge boon to our customers (beekeepers).

Thanks!