Adding dissimilar panel string to existing install

[MichaelK!]

It's ok to have two different strings of panels as long as their combined voltages are within 5% of each other. Remember, in series, volts add, and amperage stays the same. In parallel, voltage stays the same but amperage adds.

Let's say for example you have two strings of panels, one producing 5.5 amps at 72V, and a second string producing 8.0amps at 74V. Combine the two strings in parallel and you might get about 13.5amps at ~ 73V.

[bob-n]

Please give us more information on what you have and are adding. Can you find the brand and model of the inverters? How many panels are there now? How many are you adding?

If you have an inverter with two string inputs and only one string input is used, then you can put something different on the other string input with no penalty.

There are limits on the number of panels that you can put on one string input. Also, it is different if you are off-grid vs grid-tied. That's where it gets more complex.

[Island mon]

I want to add a similar, but different series string to a existing array.
do I separate it with a separate controller?
if not, do I bog the entire array down adding this 12% lower amp string?
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