Happiness is the new depression? You might think so from the sunnier, sexier dispositions of a few of the most celebrated young singers of late. Taylor Swift turned on a dime from the shadowy “Reputation” to the pastel-colored “Lover;” Billie Eilish, while not intending the title “Happier Than Ever” to be a unilateral statement, has recorded something as contented, or at least well-adjusted, as “My Future” and gone uniron­ically blonde.

But none of these others has done a 180 quite as dramatic as Lorde, who’s hardly recognizable on her third album, “Solar Power,” as the same artist who made precocious darkness her brand in 2013’s career-making “Roy­als” (recorded when she was a world-weary cynic of 16) and 2017’s even better “Melodrama.” Now a veteran star who, at 24, is coming back from a four-year layoff, Lorde sent a jolt through her fandom — who had reasonable expectations that she might pick up at least a little where she left off, looking, if not sounding, a little Goth — with the release earlier this summer of an unabashedly solstice-powered title track  and some literally cheeky dark-side-of-her-moon album art.

It wasn’t a misleading tease. “Solar Power,” the album, like “Solar Power,” the single, really does turn out to be that different — it’s all melatonin and no melodrama.

If song names like the title track and “Oceanic Feeling” sug­gest something less to do with Kate Bush influences than a thinking-person’s-Colbie-Caillat record, that’s not a false impres­sion. Lorde sums up her image and attitude changes near the close of the collection when, in a statement of reversed purpose, she sings: “Now the cherry-black lipstick’s gather­ing dust in a drawer / I don’t need her anymore.” (Sephora, adjust your stock orders accordingly.)

Out of a dozen songs, or 14 songs on the deluxe edition, just a few skew more toward reflective rue than breezy optimism. The feel of being young, in love and sun-soaked seeps from the record’s psychology to its pro­duction, too, with co-producer Jack Antonoff arranging in an indie-folk style so determinedly gentle it almost makes “Folklore” and “Evermore” sound like “Led Zeppelin III” and “IV.”

Lorde has referred to this as her “weed album,” although there’s not quite as much haze blocking the ultraviolet rays as that descriptor might suggest. (She was countering the New York Times’ question about whether it was an acid album… nope.) The lyrics are too cogent and the melodies too distinct and succinct for that. But there may be a kind of weediness to how few sops there are to the topical commerciality of the top 40 anywhere in these soft exhalations and exultations. Only about half the tracks have any notable percussion to speak of, much less the programmed beats expected of a pop superstar of Lorde’s caliber and calibration. However much instrumentation is cred­ited on the tracks, what you’re mostly going to hear is Antonoff playing his electric guitar as if it were an acoustic  — and, on a lot of the best tracks, Phoebe Bridgers and Clairo joining in for  lus­cious harmonies to bridge the hippie-chick and scientific-THC eras. (Robyn also makes a cameo appearance, but in a dreamy spoken-word coda; fun as that is, let’s try for a proper duet next time, shall we?)

Does the drastic gear shift work? It does, although there’s no avoiding that it may divide a previous fan base that looked at her widow’s peak and imagined they saw a dagger. She spends enough time singing about the effects of fame and fortune — albeit in an only slightly jaundiced, not too bothered way — that some may wonder if she’s gone and become a “royal” herself. There are moments on the album where she seems to be adopting confessional writing for its own sake, having gone a bit too far in lessons learned from Taylor Swift about how it’s specificity that makes a song.

This is surely one of the few albums ever released that has two different songs referring to the artist’s experiences at the Grammys. “Once upon a time in Hollywood when Carole called my name,” she sings at the start of “California,” referencing Carole King handing her her song of the year award — a memory that few listeners will relate to. Later, in “Helen of Troy,” she strikes a more sour note by talking about howone minute I was killing ‘em all / And the next, a brown suit wouldn’t let me perform,” recalling the time she opted out of the telecast when she wasn’t going to be allowed to perform an original song. These are details of her life that are fun to look up — hey, Google says “arm in a cast at the museum gala” refers to attending the 2016 Met party! — and do contribute to an overall sense of truth-telling, but kinda come off as humble-brags at best.

But small things like this are quibbles in the face of how well Lorde has pulled off one of the more difficult stunts in pop music: making a happy album that’s a good album. Maybe we could have seen it coming in the four-year-old “Melodrama”; that was an album that was half about mourning or being angry about a failed first love, and half looking forward to the future, although what she saw as her happy ending then seemed to have less to do with finding perfect romance than just giving up feeling old before her time and joining the party. On “Solar Power,” there are some wonderful moments where it’s clear that for her now, love is a many-splendored thing.

One of the best of these is “The Man With the Axe,” in which Lorde pretty much finally confirms to the world who her long-rumored love interest is that it’s a non-famous guy with an “office job” and “silver hair” (and whose “favorite record was the same as my father’s”). On a previous Lorde record, the title might have been as violent as it sounds, but now when she sings “You felled me clean as a pine,” it’s the tenderest coo she can put in her love interest’s ear. In “Big Star,” an under-three-minute song where she sings only against Antonoff’s electric guitar, the big star of the title is her significant other, who’s “too good for me” and invokes “shivering pines and walls of colour.” Leaving him to go get on a plane makes her so anxious, the parting is guaranteed to make her “toss up” — a very lovely thought, if not necessarily a lovely image.

This beau isn’t the only one she has an affecting affection for. “Hold No Grudge,” a bonus track is a fascinatingly good-hearted but resigned reach-out to the ex-love she wrote about on the first two albums. “Just when I go to close the gates permanently / I realize that isn’t me,” she sings, unable to turn even the saddest song on the album very melancholy.

But the album finds its crest a little earlier in “Oceanic Feeling,” the closer of the pre-bonus-track part of the album, where she goes diving off cliffs at a favorite family spot back home in New Zealand with her younger brother, wondering aloud about his future and, of course, her own. “If I have a daughter / Will she have my waist or my widow’s peak? / My dreamer’s disposition or my wicked streak?” One would hope both, even if “Solar Power” is, to its ultimate benefit, far bigger on sweet than bitter.