No, you chain them together to EITHER add the voltages together OR add the amp hours together.
Like LDB said, your house bank is not a bunch of individual batteries, it's one great big battery (once chained together in parallel).
View attachment 22786
What you have here is three 12-volt batteries of 100 Ah each. (this diagram works for 3, or 2, or 4, or 90 batteries)
One you've connected all of the negative terminals together, and then all of the positive terminals together, you no longer have three individual 12-volt 100 Ah batteries, but rather one big 12-volt 300 Ah battery with one positive and one negative terminal on it.