PV Configuration
4S1P? 2S2P? 1S4P? What is all this mean? The following diagrams are a few examples of different PV configurations and what might be best for you when sizing an array.
Before we start talking about PV configuration we need a clear understanding of the charge controller. If you are dealing with a PWM charge controller then you need to try and match panel voltage with battery voltage. If we are using a MPPT charger as shown above we can use much higher panel voltage by stacking them in series. We need to understand the two number for example this controller (75/15). This charger can accept maximum 75 volts at Voc (panel open circuit voltage which can be found on back of panel). The 15 denotes the maximum amperage the charge controller will deliver in this case 15 amps. If our battery voltage is 12v the maximum power this will deliver is 180- watts, if we use a 24v battery it will deliver 360 watts.
1S4P means 1 set of panels in series, 4 panels in parallel, hence 1 series 4 parallel. If the above array were 100 watt, 12 volt panels (18Vmp), they would produce about 22 amps at maximum. A 75/15 charge controller would only be able to deliver 15 amps at battery voltage which has to be 5 volts below panel voltage. So most likely this array would not be most suitable for a 75/15.
4S1P is quite the opposite of a 1S4P. We now stack all the voltages so for the same 100 watt 12v panels we would be producing 1/4 the amperage at 4 times the voltage. This array would produce about 5.5 amps at 72 volts. When sizing a charge controller it important to use Voc which is the voltage at open circuit. The Voc of a 12v panel can be found on the back of your panel but is usually about 22v. A 4S array of these panels would be about 88 volts making this configuration no good for a 75/15 charge controller. We could switch the configuration of panels or move up to a larger controller.
2S2P is a combination of the two above. With the same panels we will now produce about 11 amps at 36volts (44Voc). With a 12v battery we would be able to only harness 15 amps or 180 watts which would be only half of the potential of this array. With a 24v battery we could harness 360 watts of solar (90%) This would be those most ideal configuration if our only controller option was 75/15 although ti would be reccomended to move to the next size up to harness all the solar potential.
In conclusion there are infinite combinations of parallel and series it is just a matter of what your charge controller can handle. The main things to keep in mind is, it is not possible to connect a 2S array in parallel with a 3S array, we must keep array even. We must use all alike panels in the array (brand, age, type and wattage).