It’s too late - I’m working for it for a few hours now and I formatted the SD card, new rasbian…
But thanks for help.

My plan was to install all modules and then copy the config.js back.

I did it like it is written in the MM manual.

git clone && npm install

But I saved the MM folder with all my settings.

That’s a good beginning :D
At the moment I have to install MM new, because the update failed and the system was stuck.
I will test it when MM ist working again.

How to get the MMM-Fronius results in a table?
It would be nicer with the code from @Cetax but at the moment it would be ok for me when I know what I have to change to get the result in a nicer form.

Is it possible to tell me how it works with the table?
In that case on the original code.

Wunderground API calls:
current weather:

https://api.weather.com/v2/pws/observations/current?stationId=here_PWS&format=json&units=m&apiKey=here_API

7 Day forcast:

https://api.weather.com/v2/pws/dailysummary/7day?stationId=here_PWS&format=json&units=m&apiKey=here_API

I don’t have an old version, but here the actual forecast:

{"summaries":[{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2020-12-26T22:59:49Z","obsTimeLocal":"2020-12-26 23:59:49","epoch":1609023589,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":91.02,"uvHigh":0.0,"winddirAvg":189,"humidityHigh":97,"humidityLow":86,"humidityAvg":91,"qcStatus":0,"metric":{"tempHigh":5,"tempLow":-1,"tempAvg":3,"windspeedHigh":21,"windspeedLow":0,"windspeedAvg":7,"windgustHigh":31,"windgustLow":0,"windgustAvg":9,"dewptHigh":3,"dewptLow":-1,"dewptAvg":2,"windchillHigh":5,"windchillLow":-1,"windchillAvg":2,"heatindexHigh":5,"heatindexLow":-1,"heatindexAvg":3,"pressureMax":1022.82,"pressureMin":1002.71,"pressureTrend":-0.82,"precipRate":1.80,"precipTotal":0.30}},{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2020-12-27T22:59:15Z","obsTimeLocal":"2020-12-27 23:59:15","epoch":1609109955,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":19.45,"uvHigh":0.0,"winddirAvg":198,"humidityHigh":95,"humidityLow":81,"humidityAvg":90,"qcStatus":1,"metric":{"tempHigh":5,"tempLow":3,"tempAvg":4,"windspeedHigh":27,"windspeedLow":2,"windspeedAvg":12,"windgustHigh":42,"windgustLow":4,"windgustAvg":17,"dewptHigh":3,"dewptLow":1,"dewptAvg":2,"windchillHigh":4,"windchillLow":-2,"windchillAvg":1,"heatindexHigh":5,"heatindexLow":3,"heatindexAvg":4,"pressureMax":1002.81,"pressureMin":977.62,"pressureTrend":-1.03,"precipRate":3.00,"precipTotal":10.21}},{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2020-12-28T22:59:43Z","obsTimeLocal":"2020-12-28 23:59:43","epoch":1609196383,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":79.27,"uvHigh":0.0,"winddirAvg":199,"humidityHigh":98,"humidityLow":93,"humidityAvg":95,"qcStatus":1,"metric":{"tempHigh":4,"tempLow":1,"tempAvg":3,"windspeedHigh":10,"windspeedLow":0,"windspeedAvg":2,"windgustHigh":17,"windgustLow":0,"windgustAvg":3,"dewptHigh":3,"dewptLow":1,"dewptAvg":2,"windchillHigh":4,"windchillLow":0,"windchillAvg":3,"heatindexHigh":4,"heatindexLow":1,"heatindexAvg":3,"pressureMax":982.83,"pressureMin":977.31,"pressureTrend":0.18,"precipRate":3.00,"precipTotal":3.00}},{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2020-12-29T22:59:40Z","obsTimeLocal":"2020-12-29 23:59:40","epoch":1609282780,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":61.53,"uvHigh":0.0,"winddirAvg":195,"humidityHigh":98,"humidityLow":93,"humidityAvg":96,"qcStatus":1,"metric":{"tempHigh":4,"tempLow":0,"tempAvg":2,"windspeedHigh":11,"windspeedLow":0,"windspeedAvg":2,"windgustHigh":17,"windgustLow":0,"windgustAvg":3,"dewptHigh":3,"dewptLow":0,"dewptAvg":1,"windchillHigh":4,"windchillLow":-1,"windchillAvg":1,"heatindexHigh":4,"heatindexLow":0,"heatindexAvg":2,"pressureMax":992.62,"pressureMin":981.61,"pressureTrend":0.44,"precipRate":1.80,"precipTotal":4.60}},{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2020-12-30T22:59:37Z","obsTimeLocal":"2020-12-30 23:59:37","epoch":1609369177,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":98.36,"uvHigh":0.0,"winddirAvg":189,"humidityHigh":96,"humidityLow":92,"humidityAvg":94,"qcStatus":1,"metric":{"tempHigh":4,"tempLow":3,"tempAvg":4,"windspeedHigh":15,"windspeedLow":0,"windspeedAvg":6,"windgustHigh":24,"windgustLow":0,"windgustAvg":9,"dewptHigh":3,"dewptLow":2,"dewptAvg":3,"windchillHigh":4,"windchillLow":0,"windchillAvg":3,"heatindexHigh":4,"heatindexLow":3,"heatindexAvg":4,"pressureMax":1001.63,"pressureMin":992.42,"pressureTrend":0.37,"precipRate":3.00,"precipTotal":2.31}},{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2020-12-31T22:59:34Z","obsTimeLocal":"2020-12-31 23:59:34","epoch":1609455574,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":78.05,"uvHigh":0.0,"winddirAvg":191,"humidityHigh":96,"humidityLow":87,"humidityAvg":91,"qcStatus":1,"metric":{"tempHigh":4,"tempLow":3,"tempAvg":3,"windspeedHigh":15,"windspeedLow":0,"windspeedAvg":5,"windgustHigh":18,"windgustLow":0,"windgustAvg":8,"dewptHigh":3,"dewptLow":1,"dewptAvg":2,"windchillHigh":4,"windchillLow":0,"windchillAvg":2,"heatindexHigh":4,"heatindexLow":3,"heatindexAvg":3,"pressureMax":1004.74,"pressureMin":1001.02,"pressureTrend":0.12,"precipRate":1.80,"precipTotal":2.01}},{"stationID":"IWURST7","tz":"Europe/Berlin","obsTimeUtc":"2021-01-01T11:19:57Z","obsTimeLocal":"2021-01-01 12:19:57","epoch":1609499997,"lat":53.771483,"lon":8.590322,"solarRadiationHigh":51.99,"uvHigh":0.0,"winddirAvg":191,"humidityHigh":98,"humidityLow":96,"humidityAvg":97,"qcStatus":1,"metric":{"tempHigh":3,"tempLow":-1,"tempAvg":1,"windspeedHigh":6,"windspeedLow":0,"windspeedAvg":1,"windgustHigh":7,"windgustLow":0,"windgustAvg":1,"dewptHigh":2,"dewptLow":-1,"dewptAvg":1,"windchillHigh":3,"windchillLow":-1,"windchillAvg":1,"heatindexHigh":3,"heatindexLow":-1,"heatindexAvg":1,"pressureMax":1007.11,"pressureMin":1004.23,"pressureTrend":0.17,"precipRate":4.80,"precipTotal":2.31}}]}

That is correct - here is my reply from Wounderground:

{"observations":[{"stationID":"IWURST7",
"obsTimeUtc":"2021-01-01T10:57:13Z",
"obsTimeLocal":"2021-01-01 11:57:13","neighborhood":"Deichsende",
"softwareType":"EasyWeatherV1.5.6","country":"DE",
"solarRadiation":16.0,
"lon":8.590322,
"realtimeFrequency":null,"epoch":1609498633,
"lat":53.771483,
"uv":0.0,
"winddir":193,
"humidity":98,
"qcStatus":1,"metric":{"temp":3,
"heatIndex":3,
"dewpt":2,
"windChill":3,
"windSpeed":5,
"windGust":5,
"pressure":1006.74,
"precipRate":1.19,
"precipTotal":2.01,
"elev":6}}]}

One way I forgot.

Upload the data to openweathermap and use a module it is working with, but I was unable to connect my weather station to openweathermap.