Building a solar cell 18650 battery charger + a voltage output circuit

Hello, I would like to use solar energy to use the voltage for some equipment I have. I want the final circuit to give me output 12 Volt, and I will use 18650 batteries, and I will need a battery charger for them. Can you tell me how should I start?

From a first search, I have found these:

MPPT-Solar-Controller-3-7V-4-2V-18650-Lithium-Battery-Charging-3A-Charger-Module/322670204260?ssPageName=STRK%3AMEBIDX%3AIT&var=511698918013&_trksid=p2060353.m1438.l2649

DD08CRMB-mini-DC-5V-1A-3-7V-4-2V-li-ion-Battery-Charger-Board-Module-18650-Solar/302414359706?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

3S-11-1V-25A-Balance-18650-Litio-di-Li-ione-Batterie-PCB-BMS-Protection-Board-EM/382160299037?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

What is it that you wish to power with this?
Its fairly easy to charge 18650s from a Solar panel with that MPPT charger you have linked, but to get the 3.7V to 12V needs a voltage booster and these things consume power even with nothing connected to the output.
Thats why whats going to be powered is important.

mauried:
What is it that you wish to power with this?
Its fairly easy to charge 18650s from a Solar panel with that MPPT charger you have linked, but to get the 3.7V to 12V needs a voltage booster and these things consume power even with nothing connected to the output.
Thats why whats going to be powered is important.

I assumed he would use 4 batteries
use a charger for each battery and have all the batteries in series to get 14-15 volts and then power his 12v circuit from that.
I am surprised that the Internet does not have scores of instructables (or better) guides on how to make a solar power unit for an Arduino.