With our global economy, that is a difficult question. Even defining "Made in The USA" is a challenge. Also, many American solar companies have panels manufactured in China. Also, there are offshore companies with manufacturing facilities here in the States.
However, the most significant economic impact of the solar industry is the vast number of American jobs it creates. In the USA, the solar industry is an employment juggernaut. Especially in the last few years, American job growth in the solar industry has been outstanding. Even when the panels are manufactured offshore, solar is a win for our country.