To update the meta data of an existing site you will need to provide the new parameter values in a similar way as when creating a new site. Below is an example of how to change the name of the site that was created with the solar example. To retrieve the meta data of an existing site see here.
Update site
import requests

api_key = "Your API key" # Set your API key
site_id = "a923653c-26f1-1b29-955d-ffde5d182276" # Set the site ID

payload = {
	"type": "wind",
	"name": "My new solar site", # The new site name
	"latitude": 52.5,
	"longitude": 13.4,
	"settings": {
		"model_resolution": "1h",
		"usePhysicalModels": True,
		"trainNearTermModels": False,
		"trainLongTermModels": False
	},
	"assets": [
		{
			"azimuth": 180,
			"tilt": 30,
			"capacity": 1000,
			"install_date": "2020-01-01"
		}
	]
}

url = "https://api.rebase.energy/platform/v2/sites/{site_id}"
headers = {"Authorization": api_key, "Content-Type": "application/json"}

response = requests.put(url, headers=headers, json=payload)
response.raise_for_status()
response = response.json()
Response example
{
    "message": "Site updated successfully"
}