Mppt numbers?


New to solar and want to build a small system.
The numbers 75/15 are volts /amps. How do I find out which volt (75,100) I need?
Will post a drawing of my set up later.
Thanks.

The 75 is max panel voltage (at minimum temperature).
15 is 15 A charging to the battery.
They are designed for 12v and 24v systems
Tech specs

The online mppt calculator is handy for checking panel config

How you choose what you need is really based on how much energy you need to kake in the day for 24hour use if it is offgrid.