diff --git a/main.c b/main.c
index 227c56c..15358c1 100644
--- a/main.c
+++ b/main.c
@@ -74,6 +74,7 @@ volatile bool rtc_internal_tick_flag = false; /**< flag set when internal RTC ti
 #define DDM100TC_TIMER 4 /**< timer to measure time between pulses **/
 #define DDM100TC_PORT B /**< timer ipnut capture port (TIM4_CH1=PB6) **/
 #define DDM100TC_CAPTURE TIM4_CH1 /**< time input capture used to detect pulse **/
+#define DDM100TC_RATE 1600 /**< number of impulse/kWh */
 volatile uint32_t ddm100tc_interval = 0; /**< last time interval between pulses **/
 /** @} */
 
@@ -135,8 +136,8 @@ static void process_command(char* str)
 	// parse command
 	if (0==strcmp(word,"help")) {
 		printf("available commands:\n");
-		printf("led [on|off|toggle]\n");
-		printf("time [HH:MM:SS]\n");
+		printf("led on|off|toggle\n");
+		printf("energy <Wh>\n");
 	} else if (0==strcmp(word,"led")) {
 		word = strtok(NULL,delimiter);
 		if (!word) {	
@@ -153,6 +154,18 @@ static void process_command(char* str)
 		} else {
 			goto error;
 		}
+	} else if (0==strcmp(word,"energy")) {
+		word = strtok(NULL,delimiter);
+		if (!word) { // value required but not provided
+			goto error;
+		} else { // save energy value
+			uint64_t energy = (atol(word)*DDM100TC_RATE)/1000; // get value to save
+			pwr_disable_backup_domain_write_protect(); // enable backup register write
+			BKP_DR1 = (energy>>16); // set high 16 bits
+			BKP_DR2 = (energy&0xffff); // set low 16 bits
+			pwr_enable_backup_domain_write_protect(); // protect backup register from write
+			printf("energy value set\n"); // notify user
+		}
 	} else {
 		goto error;
 	}
@@ -480,7 +493,7 @@ void main(void)
 				sensor_sdm120_measurement_request(1+sdm120_meter, sdm120_measurement); // request first measurement
 
 				// calculate and show DDM100TC measurements (base on number of pulses and interval)
-				ddm100tc_value_energy = (uint32_t)((((BKP_DR1<<16)+BKP_DR2)*(uint64_t)1000)/1600); // the meter has 1600 impulses/kWh (use 64-bit calculation to not overflow after 2684354 Wh)
+				ddm100tc_value_energy = (uint32_t)((((BKP_DR1<<16)+BKP_DR2)*(uint64_t)1000)/DDM100TC_RATE); // the meter has 1600 impulses/kWh (use 64-bit calculation to not overflow after 2684354 Wh)
 				if (ddm100tc_interval==0) { // no measurements received yet
 					ddm100tc_value_power = 0;
 				} else {