diff --git a/homeassistant/components/forecast_solar/config_flow.py b/homeassistant/components/forecast_solar/config_flow.py
index 47e1afaec7b..6066c85e74e 100644
--- a/homeassistant/components/forecast_solar/config_flow.py
+++ b/homeassistant/components/forecast_solar/config_flow.py
@@ -75,7 +75,9 @@ class ForecastSolarFlowHandler(ConfigFlow, domain=DOMAIN):
                     vol.Required(CONF_AZIMUTH, default=180): vol.All(
                         vol.Coerce(int), vol.Range(min=0, max=360)
                     ),
-                    vol.Required(CONF_MODULES_POWER): vol.Coerce(int),
+                    vol.Required(CONF_MODULES_POWER): vol.All(
+                        vol.Coerce(int), vol.Range(min=1)
+                    ),
                 }
             ),
         )
@@ -126,7 +128,7 @@ class ForecastSolarOptionFlowHandler(OptionsFlow):
                     vol.Required(
                         CONF_MODULES_POWER,
                         default=self.config_entry.options[CONF_MODULES_POWER],
-                    ): vol.Coerce(int),
+                    ): vol.All(vol.Coerce(int), vol.Range(min=1)),
                     vol.Optional(
                         CONF_DAMPING_MORNING,
                         default=self.config_entry.options.get(