Quite often the question arises on how to add solar to a system and there are two reasons people ask this question, but here is the answer to both.
Adding solar to a existing solar array.
Solar panels have voltage and amperage, VOC and ISC. if you have the space to add panels next to the ones you have already, you need to ensure the current is the same as your panels. the voltage should not exceed the total maximum voltage allowed into the inverter or charge controller. – Max DC Voltage.
Panels should be at the same angle and same direction or you may lower the output of the array where it is in series. You can add parallel panels, if you are not using optimizers.
Many inverters will have more than one MPPT port, the extra panels do not need to match the other array and you create two arrays. you can use a single mppt if you have the same voltage on the arrays, the combined parallel connection will add the amps from the array.
Adding Separate Solar
Regardless of what is set up, you can add a second array and charge controller to a battery bus bar.
You simply connect it as a standalone no problems should occur. Much of the time this approach is used for Off Grid, and is how to add a winter solar array. You do not need to match anything.
Most often with solar you will need to add a combiner box or bus bar to your solar system. Your current hardware may have a current or voltage limit where you combine solar, but if you are combining charge on the battery side, this is entirely different and frees you from restrictions.
Cautions.#
You should take care to not exceed voltage limits.
Adding additional solar in parallel to the PV side should be fused and have a isolator.
Adding a second charge controller, the feed should be to the bus and fused.
NOTES.
WE have undertaken a lot of testing for mixed arrays to see how solar and charge controllers will act in various scenario’s. You can have two arrays facing two ways connected to a bus bar (combiner) fed to the charge controller. They just add the current and the power is given regardless of the different currents from each of the arrays.
For example: Array 1; 5 amps, array 2; 7 amps, the total PV current power is 12amps.
Where solar is added before the battery (not pv side) the flow of power goes to the most needed, so should the battery have charge needs, the power will go to the battery, but if you have a load, the power can be split or go to that load. Excess will go to the battery. When the battery is full, the power will go do the load, where the load is low the charge controller stops providing power, (drawing power from the second array).
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