Porth, Newquay, Cornwall. UK  Tell A Friend
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Updated15/12/2017 19:45 

Solar PV - Immersion Heater

29/6/2013 System live at 13:00

Project:- Use excess electric generated to heat the hot water

I heat the hot water by gas, which on average costs 37p per day, based on a sample of 7 days (10th to 17th June 2013), can this be reduced ?

Yes hopefully especially in summer, I wrote an extra script to deal with this, it checks the current output agaist a threshold figure, if its below this nothing happens if above, it switches an ip power switch on which in turn operates a relay putting the immersion heater on, should the output fall below the threshold it switches off the ip relay and contactor and immersion heater, the script checks every 2 minutes output against threshhold setting.

The immersion heater is 3 kw, appears to take less than an hour to heat water,so unless brillant sunshine there will be usage from the grid, say max 1kw that equates to 12.6p, still a possible saving of 25p. Ideal solution would be a 1kw element thereby increasing the time over threshold.

Script and ip power relay installed and electrical work completed. Scripting work not finished, when complete this page will show status of immersion heater/solar pv heating.


immersion control ip switch

 Immersion Mod Cost

 including p&p
 Meter, switch and cable I already had

IP Power Switch Ebay £112-98
Din Rail Relay Ebay £14-95
Din Rail Enclosure Ebay £4-95
2m Female kettle extn lead Ebay £2-39
  Total £135-27

Solar PV - Immersion Data
Date / Time 15-12-2017 16:12
Threshold - Autumn/Winter 2000 W
Current Output 0 W
Peak Output 2692 W
Last Update 15-12-2017
Meter # 1548-44 kwh
Days solar 1044
Days Gas 518
Aprrox Savings Gas ## 1044 days @37p = £386.28
# Meter since 29th June 2013, updated most days
## Approx saving on gas,averaged 37p per day

Solar - IP Power Switch Output Port Status  Last Update  15-12-2017 16:12
Port 1Immersion Heater OFF
Port 2 -  OFF
Port 3 -  OFF
Port 4 -  OFF

Immersion Data
15-12-2017 10:52 20002035ON
15-12-2017 10:54 2000464OFF
15-12-2017 10:58 20002143ON
15-12-2017 11:18 2000537OFF
15-12-2017 11:26 20002416ON
15-12-2017 11:28 2000893OFF

Immersion Time
Date / Time ONDate / Time OFFTime ONTotal Time On
15-12-2017 10:5215-12-2017 10:5422 mins
15-12-2017 10:5815-12-2017 11:182022 mins
15-12-2017 11:2615-12-2017 11:28224 mins


4/1/2016 - One string connected, other faulty, no immersion heating.
2/2/2014 - Added Status of the ip power switch ports
29/6/2013 - Electrical work completed, live at 13:00, then the fog rolled in off the sea.
23/6/2013 Started on addition to script to show minutes on and total time over threshold.

Page under construction - updated 2nd February 2014
Update to display ip switch port status