The Light Thieves (3 book series) by Helena Duggan

Clever, quirky and hugely imaginative, discover the eagerly anticipated new eco-adventure series from the bestselling author of A Place Called Perfect. Who would you trust to save the world…a boy or a billionaire? The earth has shifted on its axis and a mysterious dark mark has appeared on the sun – the whole world is in peril! But billionaire tech genius Howard Hansom has a plan… When Grian’s sister goes missing he’s convinced she has run off to Hansom’s new city to help save the world. But when Grian and his two friends Jeffrey and Shelli track her there they find that nothing is quite as it seems. Why is everything so secret? Where is the mysterious Area 13? What does Howard Hansom want with all the people he has enticed to live in his city? The days are getting darker but what’s really happening to the sun?