If did a complete flow as test. Maybe it helps.
[{"id":"cd5910130d6f031b","type":"change","z":"5ad55a7b0d4580eb","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"$zip(\t $keys(payload.data),\t $zip(\t payload.data.*#$i[($i%2)=0],\t payload.data.*#$i[($i%2)=1]\t )\t).\t {\t \"measurement\" : \"Solarprognose2\",\t \"timestamp\":$number($[0])*1000,\t \"fields\":{\t \"Datum\": ($moment($[0],'X').format('DD.MM.YYYY HH:mm:ss'))[0],\t \"Prognose_W\":$[1],\t \"Prognose_Wh\":$[2]}\t }\t","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":650,"y":2820,"wires":[["d15dac041a441f86","c4947de713be0f3d","690ba182ca09fbb8"]]},{"id":"d15dac041a441f86","type":"debug","z":"5ad55a7b0d4580eb","name":"Daten","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":810,"y":2740,"wires":[]},{"id":"ee1f3162147de5e3","type":"http request","z":"5ad55a7b0d4580eb","name":"","method":"GET","ret":"txt","paytoqs":"ignore","url":"https://www.solarprognose.de/web/solarprediction/api/v1?_format=json&access-token=xxxxxxxxxxxxxxx&item=location&id=3747&type=hourly","tls":"","persist":false,"proxy":"","insecureHTTPParser":false,"authType":"","senderr":false,"headers":[],"x":310,"y":2820,"wires":[["953203383cdb5a24"]]},{"id":"953203383cdb5a24","type":"json","z":"5ad55a7b0d4580eb","name":"","property":"payload","action":"","pretty":false,"x":450,"y":2820,"wires":[["cd5910130d6f031b","8c21582d4d69d761"]]},{"id":"bceeef4ce1883e59","type":"cronplus","z":"5ad55a7b0d4580eb","name":"","outputField":"payload","timeZone":"","storeName":"","commandResponseMsgOutput":"output1","defaultLocation":"","defaultLocationType":"default","outputs":1,"options":[{"name":"schedule1","topic":"topic1","payloadType":"default","payload":"","expressionType":"cron","expression":"4 6,9,11,13,15 * * *","location":"","offset":"0","solarType":"all","solarEvents":"sunrise,sunset"}],"x":160,"y":2820,"wires":[["ee1f3162147de5e3"]]},{"id":"690ba182ca09fbb8","type":"influxdb batch","z":"5ad55a7b0d4580eb","influxdb":"64647facf05f4c10","precision":"","retentionPolicy":"","name":"","database":"database","precisionV18FluxV20":"ms","retentionPolicyV18Flux":"","org":"mwdebian","bucket":"Node-Red Test","x":900,"y":2820,"wires":[]},{"id":"8c21582d4d69d761","type":"debug","z":"5ad55a7b0d4580eb","name":"result","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":610,"y":2740,"wires":[]},{"id":"64647facf05f4c10","type":"influxdb","hostname":"127.0.0.1","port":"8086","protocol":"http","database":"database","name":"MWDebian InfluxDB","usetls":false,"tls":"","influxdbVersion":"2.0","url":"http://mwdebian.fritz.box:8086","rejectUnauthorized":false}]
The JSON Node can be deleted as you can specify in the Http-request that you want to have a JSON object.
I used the batch Node - but I guess you can use the normal out Node as well with a different syntax
Do I guess you have to use the batch node when you want to specify other timestamps as the current timestamp. This is what I found out after reading the description:
