Thanks for the additional information.
Current in a circuit is always the same, no matter where you look in that circuit. So if you imagine a battery torch, no matter where you measure the current, it should have the same numeric value. That’s why you only need one sensor to measure the current from a solar panel.
The current sensors in the ACS range don’t measure voltage. You’d need another way to measure voltage, if it was important to calculate power. It depends on why you want to measure, as well as what you want to measure. For me, current from a solar panel is often a good enough measure, especially when it is being fed into a battery that generally has the same voltage, give or take a little bit.
The current sensors in the ACS range are best for measuring DC, either stable DC or AC that varies by no more than 90 kHz (a limit of rate change that the sensor can report), but the Arduino has a limit on how often it can read the measurement. Solar panels generate DC, and it is very stable. Wind turbines generate either stable DC, or varying DC, it depends on how they are made, and what circuit is built into them.
Measuring AC is a different problem entirely, but from what you’ve described you don’t yet have any AC to measure. I’m randomly presuming you are planning to use a battery to store the energy.
The ring terminal connectors are useful if you have a crimping tool, or you can solder wires to the circuit board. You have to break one of the wires in the cable from the solar panel, and attach those wires to the large pads, such that the current generated by the panel has no choice but to flow through the black chip, the ACS715.
You’ll need to solder pin headers or wires to the three pads at the other side of the board so they can connect to the Arduino.
Hope that helps. I expect more questions.