Solar Manager and NodeMCU (esp8266)

I am new to this so I may ask stupid questions, I would like to power the NodeMCU (esp8268 with micro USB) using the output of the Solar manager (5V 1A) which will be connected to 2x 5V solar panels and 1 Li Ion 3.7 battery. The thing I don't understand is during the night the will be no solar activity and the power will be drawn from the 3.7 battery to keep the NodeMCU going connected to the micro USB. Now how can 3.7 become 5V as I far as I know it is not a step up transformer! The only way would be to connect to the VIN of the Esp8266 and not to the micro USB as suggested by the diagram on the Solar Manager connection diagram:

https://www.dfrobot.com/product-1712.ht ... %20manager

so something like this would be more realistic:

https://www.hackster.io/Tiobel/esp8266- ... ion-1ea3ec

Have I got all this wrong? Just trying to justify getting the Solar manager to power the Esp8266 (NodeMCU 12E).