diff --git a/src/india_api/internal/inputs/indiadb/client.py b/src/india_api/internal/inputs/indiadb/client.py
index ab4b102..2d9e8f1 100644
--- a/src/india_api/internal/inputs/indiadb/client.py
+++ b/src/india_api/internal/inputs/indiadb/client.py
@@ -1,10 +1,12 @@
 """India DB client that conforms to the DatabaseInterface."""
+import os
 import datetime as dt
 import pandas as pd
 import logging
 from typing import Optional
 from fastapi import HTTPException
 from uuid import UUID
+import sentry_sdk
 
 from pvsite_datamodel import DatabaseConnection
 from pvsite_datamodel.read import (
@@ -370,6 +372,31 @@ def post_site_generation(
                 )
 
             generation_values_df = pd.DataFrame(generations)
+            capacity_factor = float(os.getenv("ERROR_GENERATION_CAPACITY_FACTOR", 1.1))
+            site = get_site_by_uuid(session=session, site_uuid=site_uuid)
+            site_capacity_kw = site.capacity_kw
+            exceeded_capacity = generation_values_df[
+                generation_values_df["power_kw"] > site_capacity_kw * capacity_factor
+            ]
+            if len(exceeded_capacity) > 0:
+                # alert Sentry and return 422 validation error
+                sentry_sdk.capture_message(
+                    f"Error processing generation values. "
+                    f"One (or more) values are larger than {capacity_factor} "
+                    f"times the site capacity of {site_capacity_kw} kWp. "
+                    # f"User: {auth['https://openclimatefix.org/email']}"
+                    f"Site: {site_uuid}"
+                )
+                raise HTTPException(
+                    status_code=422,
+                    detail=(
+                        f"Error processing generation values. "
+                        f"One (or more) values are larger than {capacity_factor} "
+                        f"times the site capacity of {site_capacity_kw} kWp. "
+                        "Please adjust this generation value, the site capacity, "
+                        "or contact quartz.support@openclimatefix.org."
+                    ),
+                )
 
             insert_generation_values(session, generation_values_df)
             session.commit()
diff --git a/src/india_api/internal/inputs/indiadb/test_indiadb.py b/src/india_api/internal/inputs/indiadb/test_indiadb.py
index 7c8e28b..385a34c 100644
--- a/src/india_api/internal/inputs/indiadb/test_indiadb.py
+++ b/src/india_api/internal/inputs/indiadb/test_indiadb.py
@@ -1,4 +1,5 @@
 import logging
+from fastapi import HTTPException
 import pytest
 
 from india_api.internal import PredictedPower, ActualPower
@@ -105,3 +106,14 @@ def test_post_site_generation(self, client, sites) -> None:
             generation=[ActualPower(Time=1, PowerKW=1)],
             email="test@test.com",
         )
+
+    def test_post_site_generation_exceding_max_capacity(self, client, sites):
+        try:
+            client.post_site_generation(
+                site_uuid=sites[0].site_uuid,
+                generation=[ActualPower(Time=1, PowerKW=1000)],
+                email="test@test.com",
+            )
+        except HTTPException as e:
+            assert e.status_code == 422 
+            assert "generation values" in str(e.detail)
\ No newline at end of file