Solange Knowles used to be jealous of older sister Beyoncé's close bond with Kelly Rowland.

The 30-year-old singer admits it wasn't easy growing up alongside the childhood friends, who went on to form the successful R&B group Destiny's Child together, and sought solace in songwriting because she often felt like an outsider when she was with them.

The 'Seat at the Table' hitmaker said: ''My sister and Kelly [Rowland] were the same age, which is like a built-in best friend in the house; they were extremely close. Writing felt like this insular thing that I could go back in my room and express all that I would observe, all the emotions that would arise. It felt like mine, my little thing.''

Solange revealed she also felt ''lonely'' when she gave birth to her son Julez, 12, with ex-husband Daniel Smith at the age of 17.

She told the March issue of Elle magazine: ''It was one of the most bittersweet moments of my life because I was so in love with Julez, and having spent a lot of time on the road, I yearned to be in one place, to have the opportunity to really ground myself with him. But it was isolating and lonely, and so cold and dark. And it was just Julez and me most of the time. It was hard to imagine being able to progress in my career in any way.''