Can a person daven Ma’ariv after Plag by himself if he davened Mincha before Plag, or is that only possible BeTzibur? Thank you.
The minhag is that we daven maariv specifically after it is nighttime, even if one already davened mincha before plag, and there isn’t a difference between davening with a minyan or without a minyan. However if one already davened mincha before plag and he is in a pressing situation then he may daven maariv after plag even though our minhag is generally not to do this. The difference between davening with minyan is that when there is a situation that the minyan davened mincha, and if everyone will go home they won’t come back for maariv, then it is permitted for the minyan to daven both mincha and maariv between after plag. An individual person however may not do this, and he should wait until later to daven maariv.
O:CH 233-1, M:B ibid 11, 13.