ESP8266 Community Forum

- Thu Mar 29, 2018 6:36 pm #74990 Hi all,

I'm working on an ESP8266 probe only powered by solar cells.
It means its power will slowly rampup from 0 to 3.3v at sunrise.

The chips is controlled by it's CH_PD pin and wake up around 3v and I'm using some ESP-201 model.

My question is to know if it will damage my ESP or if it's harmless.

Thanks

- Thu Mar 29, 2018 6:49 pm #74991 There should be no problem as far as damage to the module. The concern that I have is that you may not have enough power to operate as the voltage gets to the 3 volt level. You may have enough voltage to turn on the circuit but you will not have enough current to keep it operating. As soon as the ESP tries to run it will try and draw more current and that load on the solar panel will cause the voltage to drop. This cycle will repeat over and over. As you have more sun the ESP may be able to get further in the code but it may not be able to complete what it is to do. Eventually it will if the sun is bright enough if your solar panel has enough capacity.

I don't see any reason for it to get damaged. I just don't think it is the best way to operate from a solar panel. I would store the power into batteries. If you don't want batteries then I would have the solar panel feeding a large capacitor. Then have a higher voltage trip point that would enable a switching supply to draw the power off the capacitor and solar panel providing that power to the ESP. (at 3.3v)

- Fri Mar 30, 2018 5:02 am #75006 It's what I've planned to do : stock energy on a 2200uF capacitor.

I'll have also a DS18B20 to power and I duno if it's harmless to it too to be under powered (providing, the temperature conversion will happen only when the ESP is up, obviously).
If so, I'm planning to control its power to a Mosfet ...

- Fri Mar 30, 2018 7:35 am #75014 I would go for 10 times that. I think I will need to try this myself. I have a few solar panels I can use, but it will have to wait until next week when I'm back at work.