A motorized sailplane pilot departing a non-towered airport reported a NMAC with an aircraft not on CTAF which overflew them and into an active parachute jump area.

Narrative

ZZZ is home to X Skydiving; which claims they conduct XX;000 jumps onto the airport per year. Parachutists descend in large numbers to a landing zone on the southwest side of the airport. Charts depict a Parachute Jump Area (PJA) around the airport from surface to XX;X00 feet; ASOS constantly warns pilots to 'avoid overflight when parachute operations are in effect'; and the pilot of the jump plane on frequency at the time of the near-miss was repeatedly announcing on CTAF that operations were in effect. I departed the airport in self-launching motor glider and made a left downwind departure. Climbing through 7;100 feet; a small aircraft overflew me and into the PJA. There was no radio call from the small aircraft. I radioed the jump plane and alerted them to the passage of a NORDO plane through the jump zone at 7;100 feet. The pilot thanked me for the head's up. I don't know if they altered their jump plans.Aircraft Y passed behind me traveling southwest at 7;380 feet and 143 knots. I was traveling northwest at 7;095 feet and 75 knots. There was 285 feet vertical separation and 427 feet lateral separation. I am not so sure of these numbers. It felt much closer. My plane is equipped with ADS-B OUT and I have several onboard collision avoidance displays. I did not see any warnings. My first indication was the flash of Aircraft Y passing over from my 4 o'clock to my 9 o'clock. I was flying solo from the left seat and did not have the ability to see behind and to the right. I would have been at their 11 to 12 o'clock and they were overtaking me by 70 knots. As a faster airplane overtaking a slower glider; the small aircraft should have seen and avoided me. They also should have exercised more caution flying into an active Parachute Jump Area. We were both extremely lucky there was no collision.