diff --git a/src/access/esmf_trace/library.py b/src/access/esmf_trace/library.py
index 0b8a35c..d59178c 100644
--- a/src/access/esmf_trace/library.py
+++ b/src/access/esmf_trace/library.py
@@ -5,6 +5,7 @@
 from .batch_runs import run_batch_jobs
 from .config import DefaultSettings, PostRunSettings, PostSummarySettings, RunSettings, load_yaml_config
 from .postprocess import post_summary_from_yaml
+from .utils import normalise_str_list
 
 
 def run_from_config(
@@ -75,7 +76,7 @@ def __init__(
         branches: list[str],
         post_base_path: str | Path,
         exact_paths: list[Path],
-        model_component: str,
+        model_component: str | list[str],
         branch_pattern: re.Pattern[str] | None = None,
         pets_components: list[str] | None = None,
         pets_prefix: str = "0",
@@ -87,7 +88,7 @@ def __init__(
         branches: Experiment branch directory names; each string must match the regex provided in branch_pattern
         post_base_path: where esmf-trace writes postprocessed outputs for this config
         exact_paths: list of exact paths for each branch
-        model_component: comma-separated esmf component selector string.
+        model_component: comma-separated esmf component selector string or list[str] of selectors
         branch_pattern: regex pattern to parse layout values, with capture groups for each layout variable
         pets_components: list[str], keys to include in pets string in order
         pets_prefix: str, prefix for pets string (default "0")
@@ -120,8 +121,8 @@ def _validate(self) -> None:
         if not self.branches:
             raise ValueError("At least one branch must be provided.")
 
-        if not isinstance(self.model_component, str) or not self.model_component:
-            raise ValueError("model_component must be a non-empty string.")
+        if normalise_str_list(self.model_component) is None:
+            raise ValueError("model_component must be a non-empty string or list[str].")
 
         if not isinstance(self.max_workers, int) or self.max_workers < 1:
             raise ValueError("max_workers must be an int >= 1")
@@ -208,7 +209,7 @@ def build_config(self) -> dict:
         return {
             "default_settings": {
                 "post_base_path": str(self.post_base_path),
-                "model_component": self.model_component,
+                "model_component": normalise_str_list(self.model_component),
                 **self.default_settings,
             },
             "runs": runs,
@@ -271,12 +272,8 @@ def build_config(self, runs: list[dict]) -> dict:
             "timeseries_suffix": self.timeseries_suffix,
         }
 
-        if self.model_component is not None:
-            default_settings["model_component"] = (
-                self.model_component
-                if isinstance(self.model_component, list)
-                else [s.strip() for s in str(self.model_component).split(",") if s.strip()]
-            )
+        default_settings["model_component"] = normalise_str_list(self.model_component)
+
         if self.pets is not None:
             default_settings["pets"] = (
                 self.pets
diff --git a/src/access/esmf_trace/utils.py b/src/access/esmf_trace/utils.py
index 03df9c7..a36ae81 100644
--- a/src/access/esmf_trace/utils.py
+++ b/src/access/esmf_trace/utils.py
@@ -89,3 +89,11 @@ def construct_stream_paths(traceout_path: Path, pet_indices: list[int], prefix:
     """
     traceout_path = Path(traceout_path).expanduser().resolve()
     return [traceout_path / f"{prefix}_{p:04d}" for p in pet_indices]
+
+
+def normalise_str_list(value: str | list[str] | None) -> list[str] | None:
+    if value is None:
+        return None
+    if isinstance(value, list):
+        return [str(v).strip() for v in value if str(v).strip()]
+    return [s.strip() for s in str(value).split(",") if s.strip()]