I think the problem is that something is wrong with the ENTSO-E feed for solar and wind power in Switzerland. Data is given as "N/A" on their webpage, too, and it states that: "Due to changes to a different primary data provider, no data is published for Production Type Solar and Wind Onshore. The missing data will be published retrospectively by 28th Mar 2019."

Given that the 28th Mar 2019 has long passed, I am not very optimistic that the feed will be restored anytime soon... and unfortunately I don't know of any other (e.g. primary) public source, either.