1 Ω = 1 V/A. ... Thus the names of all units start with a lower-case letter, except at the beginning of a sentence or in capitalized material such as a title. In keeping with this rule, the unit symbols for Ampere is a capitalized "A" and Volt is capitalized "V" because both unit names are based on the names of scientists.

Should units of measurement be capitalized?

Units of Measure.

Do not capitalize a unit of measure unless the abbreviation contains a capital letter.

Do you capitalize Watt?

Watt (surname) is a proper noun, and capitalised. Whereas watt (unit) is not a proper noun and is not capitalised, even though it derives from the surname. Watts are capitalised at the beginning of a sentence, because that is a local formatting rule which takes precedence.