diff --git a/docs/manual.md b/docs/manual.md
index 2370e7c..5891ad7 100644
--- a/docs/manual.md
+++ b/docs/manual.md
@@ -168,6 +168,8 @@ The overview section shows some global information about the router.
 
 The temperature is coming from the sensor installed in the router box.
 
+**A JSY or PZEM is required to see the measurements.**
+
 ## Dashboard / Output 1 & 2
 
 The output sections show the state of the outputs and the possibility to control them.
@@ -184,6 +186,8 @@ The output sections show the state of the outputs and the possibility to control
 
 **Energy:**
 
+**A JSY or PZEM is required to see the measurements.**
+
 - `Power`: Routed power.
 - `Apparent Power`: Apparent power in VA circulating on the wires.
 - `Power Factor`: Power factor (if lower than 1, mainly composed of harmonic component). Ideal is close to 1.