At the age of two, Skelly sailed to the United States from Ireland with his family aboard the SS America. His parents settled in Roanoke, Virginia where Skelly attended public schools. He went on to earn his undergraduate degree from the University of Notre Dame and his M.B.A. from Harvard Business School. After college, he joined the Peace Corps and served in Costa Rica.
Skelly has been married to Anne Whitlock since 1991. The couple has three children: two boys and a girl. Anne earned a degree in Business Finance from the University of Massachusetts Amherst and a degree in Public Policy from the John F. Kennedy School of Government at Harvard. Anne serves on the board of the Denver Harbor Family Clinic and works at the Harris County Healthcare Alliance.
In February 2011, Skelly donated a kidney to his sister.
In 1999, Skelly joined Horizon Wind Energy, when it was a two-person operation, and helped it grow into a multi-billion dollar company over the next nine years. In 2005, investment bank Goldman Sachs bought Horizon, then a privately held company known as Zilkha Renewables. Goldman Sachs sold Horizon, which had grown to the third largest wind company in the United States, for $2.2 billion for a reported gain of nearly $1 billion. In 2006, the Houston Business Journal quoted Skelly as saying, "Houston is the center of energy, and as renewable energy, including wind, plays a bigger role. There is an opportunity for Houston to be involved in the growth for that segment."
In 2009, Skelly founded Clean Line Energy Partners, a company focused on the biggest challenge facing renewable energy—moving renewable energy from resource areas to distant consumer markets. Clean Line is an independent developer of high voltage, long-haul transmission lines, providing transmission solutions to generators and load-serving utilities in order to efficiently interconnect clean energy with consumers.
Prior to his time at Horizon Wind, Skelly worked at Energia Global and New World Power. Both positions focused on energy projects in Latin America. Before entering the energy industry, he served as a founding partner and manager for Rain Forest Aerial Tram in Costa Rica.
In November 2008, Skelly faced three-term incumbent John Culberson in the Congressional election for Texas’ 7th district. Skelly's campaign received national attention when he raised more money than any candidate, incumbent or challenger, Democrat or Republican, running for the House of Representatives that year.
The 7th district has traditionally been one of the most Republican districts in the nation, as well as the most Republican district in the Houston area. However, Skelly positioned himself as the strongest Democrat to run in the district in almost 40 years. Despite his strong showing, Skelly was defeated by Culberson.
Skelly serves on the Houston Parks Board and is a co-founder of the Houston Renewable Energy Network. Skelly also serves on the advisory boards of C12 Energy and Trees for Houston.