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.
When connecting multiple panels in series, connect the positive post from one panel to the negative post of the next panel, and so on. The voltage values of each panel are added up together, which means it gets a sum at last. The amperage reading will not be added up, and stay the same no matter how many solar panels you connect in series.
E.g. 2x12V panel wired in series, the voltage up to 24V, while the amps stay as one panel amps parameter.
When wiring panels in parallel, hook up the positive or negative wire from one panel to the positive or negative wire of the next panel, and so on. In parallel connection method, you connect the wires with the same sign between panels. Y branch connectors are necessary for the parallel connections. On the contrary to series connection, the voltage values are not added up and stay the same no matter how many panels you connect in parallel, and the amperage values of each panel are added up together.
E.g. 3x12V panels connected in parallel with Y branch connectors, the voltage stay at 12V, and the amps will be 3x6A=18A
When connecting panels in series-parallel, the panels wired together in series to form strings of panels. Then, the multiple strings of series-connected panels are connected to each other in parallel. This method bring the added up voltage of each panel and leave the amperage value of the panels the same within the connected string of panels, but then also adding up the amperage values of each panel string after connecting each string in parallel. The amperage values from the strings would be added depending on how many panel strings are connected in parallel.
E.g. 4x12V panels connected in 2S/2P(2 parallel strings of 2 series groups), voltage 2x12v=24v, amperage 2x6A=12A
We suggest to install the fuse between the outcome positive end of the solar panel and positive terminal connection on charge controller, you DO NOT need to install fuse between each panel when you connect the panels is series/parallel/series-parallel.
Fuse size depends on the current amps values, how many solar panels you have and how they are connected (series, parallel, or series/parallel).
E.g.If you have two 100W panels connected in series, each producing 5 amps, the total output 5 amps then. We usually maintain an extra value for the current, for example, 1.25 time compare the current, so a 6.25A fuse or a 10A fuse will be sufficient for a 2 panels series array.