Plural solo
The usual English plural of solo is solos. It can refer to several musical performances by individual performers or several passages performed alone. You do not normally need an apostrophe to form this plural.
Meaning and context
English nouns ending in o do not all form their plurals the same way. That is why a rule learned from a word such as potato should not be applied mechanically to solo. Check the established plural for the particular word.
Examples and usage
The recital included three solos describes three performances. The guitarist’s solo uses an apostrophe to show possession in guitarist’s, while solo itself remains singular. The solos were brief uses a straightforward plural with no possessive punctuation.

What to check
In a specialist discussion of music, you may encounter terminology from another language or an editorial convention specific to a score. For ordinary English prose, solos is the practical choice. Keep plural formation separate from the question of whether a performer worked alone.
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