At age 14, amateur inventor William Kamkwamba taught himself to build a windmill that could deliver power to his family’s property in Malawi, earning the remarkable teen an invitation to share his story five years later, at the 2007 TED conference. Ben Nabors’ SXSW-winning “William and the Windmill” is not the documentary one might expect about that inspirational feat — and is likely to suffer commercially because of it: Rather than focusing on the engineering achievement that started everything, the pic chronicles what came next as all that high-profile attention changed Kamkwamba’s life in ways he never could have imagined.

Trouble is, the transformation in question won’t surprise Western auds much. This is the way things work in the 20th century: Exceptional people are discovered; their stories attract attention, earning them a certain degree of celebrity; they get book deals and interview invitations, maybe even offers from Hollywood; and then the spotlight moves on to the next human-interest subject. In the process, well-meaning outsiders invest their own hopes in such cases, which becomes the subtext of Nabors’ own treatment, as  Kamkwamba longs for a normal life while his champions push for him to succeed.

Nabors jumped on the teen’s story before the explosion of media interest, but not early enough to witness the windmill-building itself; the pic half-cheats a recreation by filming Kamkwamba making repairs. The helmer was instrumental in spreading awareness of the windmill project, however, producing a six-minute short film, “Moving Windmills,” in which Kamkwamba tells the amazing story of how he built a windmill with bottle caps and bicycle parts. Perhaps Nabors assumes auds already have seen that film, or read Kamkwamba’s autobiography, “The Boy Who Harnessed the Wind,” but for whatever reason, he opts not to present afresh information contained in the short.

Instead, the doc sprinkles in some (but not all) of the details using the inventor’s own words, as the young man relays his experience to different audiences around the world. The pic shows the teen overwhelmed on the stage of the Technology, Enterainment and Design conference, giving a radio interview in Palm Springs (where he visits the enormous wind turbines in the desert) and stopping by a Chicago museum where a diorama describes his invention.

In most of these scenes, the film mutes the audio, overlaying Kamkwamba’s description of how he felt at the time. Often, the pic cuts back to Tom Rielly, the TED community director who committed to mentoring Kamkwamba for seven years. What Rielly has done to boost the teen is nothing short of amazing, and yet the film, in relying on the eccentric-looking Moving Windmills Project founder as its primary talking head, inadvertently makes his support seem like a form of self-aggrandizement, dwarfing the comparatively modest Kamkwamba.

For five years, Nabors and fellow cameraman Michael Tyburski follow along, unsteadily documenting the many opportunities the boy is given as he attends the African Leadership Academy’s inaugural class, returns home to help build a community school, and prepares to continue his education at Dartmouth. The crew doesn’t actually seem to know the kind of movie it’s making, and not until Kamkwamba signs away his life story rights to Chiwetel Ejiofor does the doc crystallize as a more nuanced alternative to the inevitable Hollywood version to come.

Tired of simply being reduced to the role of “windmill boy” in strangers’ eyes, the young man explains, “I wanted people to know me as (a) normal other person.” All along, the film supplies glimpses that remind auds how normal Kamkwamba is: struggling with math homework, learning to swim, flirting with a fellow student — the kinds of behavior to which all auds can relate, and even find a chuckle in. Considering the docu’s earnest point seems to be how well-meaning Westerners project their own hopes and expectations upon Kamkwamba, such laughter is the best possible sign that people are identifying with his experience on a human level.

William and the Windmill

(Documentary) Reviewed at SXSW Film Festival (competing), March 14, 2013. Running time: 96 MIN.

A Moving Windmills Project presentation in association with Group Theory.

Produced, directed by Ben Nabors. Camera (color, HD), Michael Tyburski, Nabors; editors, Jonathan Oppenheim, Carlos Pavan; music, Saunder Jurriaans, Danny Bensi; sound, Tony Bensusan; re-recording mixer, Luciano Vignola.

With: William Kamkwamba, Tom Rielly, Bryan Mealer, Andrea Arthello.

(English, Chewa, French, Arabic dialogue)