diff --git a/nowcasting_dataset/data_sources/pv/pv_data_source.py b/nowcasting_dataset/data_sources/pv/pv_data_source.py
index c66c811e..7893cf84 100644
--- a/nowcasting_dataset/data_sources/pv/pv_data_source.py
+++ b/nowcasting_dataset/data_sources/pv/pv_data_source.py
@@ -33,8 +33,12 @@ class PVDataSource(ImageDataSource):
     defined by image_size_pixels and meters_per_pixel.
     """
 
-    # filenames: Union[str, Path, List]
-    # metadata_filenames: Union[str, Path, List]
+    # This are just keep in for the moment, but don't do anything.
+    # THey are needed for manager.py to work
+    # TODO: #631
+    filename: Union[str, Path, List]
+    metadata_filename: Union[str, Path, List]
+
     files_groups: List[Union[PVFiles, dict]]
     # TODO: Issue #425: Use config to set start_dt and end_dt.
     start_datetime: Optional[datetime.datetime] = None
@@ -50,6 +54,9 @@ class PVDataSource(ImageDataSource):
     def __post_init__(self, image_size_pixels: int, meters_per_pixel: int):
         """Post Init"""
 
+        assert self.filename is None
+        assert self.metadata_filename is None
+
         if type(self.files_groups[0]) == dict:
             self.files_groups = [PVFiles(**files) for files in self.files_groups]