Soler entered the independent documentary cinema scene directing the documentaries Será tu tierra (1965) and El largo viaje hacia la ira (1969) about the early days of workers recently arrived in Barcelona from various regions of Spain, and 52 domingos (1966) about the hardships of young immigrants in Barcelona who, to escape poverty, aspire to become bullfighters.

In the seventies he joined what was known as “marginal cinema” with films such as: Noticiario RNA (1970), in which he used fake NO-DO newsreel images to satirise the Franco regime’s indoctrination; Sobrevivir en Mauthausen (1975) about the Spaniards deported to that German concentration camp; Gitanos sin romancero (1976) about the Roma community in Galicia and O monte e noso (1978) about the neighbourhood struggle against a motorway and to recover mountains that had been appropriated by wealthy individuals.

More recently, the documentaries Francesc Boix, un fotógrafo en el infierno (2000), Del Roig al Blau (2004), La mirada de Anna (2009) and 1000 lunas (2018) stand out. Besides documentary, he has also worked in fiction with Saïd (1998) and Lola vende cá (2000), reportage and television productions and other audiovisual projects such as video installations or more experimental films. He has combined his directing work with cinematography for other filmmakers such as Francesc Bellmunt, Helena Lumbreras and Jesús Garay.