I have two 100/50 smart solar charger on our sailboat as well as a 150/70. Occasionally one of the 100/50 does not wake up in the morning and start charging. If I go into settings on the affected charger and disable and then reenable the charger it starts charging and everything is fine again for a week or so. I have seen a thread somewhere ,where others were experiencing this too but was unable to find out if there was a resolution
Could be that the Vmp of the panel is to low to start charging.
Perhaps some details?
Sorry should have included that , panel voltage is in the mid 30s ,just not switching from off to bulk charging.