Even though the data flows back to Sense in half-second samples, or two second samples in the case of smartplugs, the data is currently only aggregated at the Sense mothership in 1 hour intervals, as well as daily, weekly, monthly and on a billing cycle basis. There’s a request in the Wishlist for smaller aggregation and export intervals, so like that if that’s what you want.
If you want greater granularity of data, and you are handy with Python or Java, you can pull real-time data using the informal API (get_realtime()), but you are going to need to poll and store it yourself. And you’ll need to poll judiciously if you do that, especially if the thing you are measuring fluctuates widely (solar on a day with passing clouds), since you are only getting a real-time sample, not aggregated data for your polling time period.