I would like to charge a 20,000mAh power bank with a 18V 20W solar panel. The power bank has 8*18650 batteries in parallel. I came out with 3 options.
The first one is to use a buck DC-DC converter with a BMS 1S in order to charge the battery pack directly.
The second one is a Q.C. module directly connected to the solar panel, since the power bank is compatible with Q.C.
The last one is an MPPT charge controller based on a CN3791. (This one comes in two versions, 9V and 12V. I don't know if it will support my solar panel.)
Which configuration will be more suitable and get the maximum amount of power? Or can you give another solution?