Small Solar panels and buck converters

Hi it’s been awhile but I am looking for some advice....

I have a small project where I want to use LiFePO4 batteries (to run an ESP32) and it will be located outside so I was hoping to use some small solar panels to recharge the LiFePO4 battery (form 26650).

Question: Can I use a simple voltage buck converter to accept the varying DC voltage in (from the solar panel(s)) to put a constant DC voltage on whatever cell charger I decide to use? I don’t care about MPPT for such a small application but I DO want it to be reasonably efficient...

Thanks for the thoughts everyone!

In general, no. Solar panels act more like current sources than voltage sources, and do not tend to work well with voltage regulators (especially the switching variety). And what should happen on cloudy days?

For DIY projects it is much safer and more convenient to work with simpler battery technologies like lead acid, NiCd or NiMH, which are very forgiving of abuse and more flexible with charging strategies.

Yes thank you. Recently I also saw some small “UPS” modules that use Li-ion cells and solar panels to keep a load supplied with power and are cheap. I am guilty of over-thinking this.....

I've used the Adafruit solar LiPo charger, and it is quite efficient, acting similarly to a maximum power point charger using the large cap.

But stupidly, they forgot to add overvoltage protection on the input. Hence the warning to buy only "approved" solar panels from their site.

Yes I have seen that module as well, but I think I will roll the dice and try some cheaper device using the same main IC as that one...

Thank you!