The trend for Silicon Valley startups applying advanced technologies to solve utility grid problems is clear — go big, or stay home. After a decade of eking out a niche in the world of advanced distribution grid power controls, Silicon Valley startup Varentec has sold its key assets for an undisclosed sum. The buyer is Sentient Energy, another Silicon Valley power line sensor startup that was acquired last year by Koch Engineered Solutions, an arm of industrial conglomerate Koch Industries.