When building a solar power system, the panels array connection is the vital part that determines how many voltage and amps comes out from the panels.The three main methods you can connect multiple panels are connecting them in series, parallel, and series-parallel.
On the other hand, if our two solar panels have both different wattage and different voltage, then parallel connection is not possible, since the panel with the lowest voltage would behave like a load, and would begin to absorb current instead of producing it, with the relative consequences. What if we have one 12V panel and two 6V panels?
Wiring solar panels in parallel implies connecting positive terminals of each panel together and wiring the negative terminals of each panel together as well. Then, they are connected to the charge controller or to the inverter of the solar system.
The connection of multiple solar panels in parallel arises from the need to reach certain current values at the output, without changing the voltage. In fact, by wiring several solar panels in series we increase the voltage (keeping the same current), while wiring them in parallel we increase the current (keeping the same voltage).
In this case, it is possible to wire the two 6V panels in series and then wire the resultant array in parallel to the 12V panel. However, the latter type of connection is at the expense of efficiency. It is therefore essential, before making a parallel connection, to carefully check the voltage of the solar panels.
Pros and cons: For large systems that are ov, say, 4 kilowatts, the series connection is the most natural choice. Series connection is also great when solar panels and the inverter are far away from each other. High voltage connection reduces power loss along the cables. The biggest enemy of solar panels connected in series is shading.