10°C
Porth, Newquay, Cornwall. UK
Updated10/11/2025 19:30 
 




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.

12-10-2023 Takes about 50p to heat water now using gas.

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

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 10-11-2025 16:34
Threshold - Autumn 2900 W
Current Output 0 W
Peak Output 3459 W
Last Update 10-11-2025
Meter # 5214.56
Days solar 2805
Days Gas 1631
Aprrox Savings Gas ## 2805 days @37p = £1,037.85
# Meter since 29th June 2013, updated most days
## Approx saving on gas,averaged 37p per day


Immersion Data
Date/TimeThresholdOutputAction
10-11-2025 10:48 29002936ON
10-11-2025 10:50 29001211OFF
10-11-2025 11:58 29003369ON
10-11-2025 12:00 29001582OFF
10-11-2025 12:30 20002407ON
10-11-2025 12:36 2000828OFF
10-11-2025 12:38 20002540ON
10-11-2025 12:40 20001100OFF
10-11-2025 12:46 20002300ON
10-11-2025 12:58 2000513OFF
10-11-2025 13:04 20002407ON
10-11-2025 13:06 2000649OFF
10-11-2025 13:10 20002483ON
10-11-2025 13:14 20001956OFF
10-11-2025 13:22 20002210ON
10-11-2025 13:24 2000870OFF
10-11-2025 13:32 20002358ON
10-11-2025 13:34 20001384OFF


Immersion Time
Date / Time ONDate / Time OFFTime ONTotal Time On
10-11-2025 10:4810-11-2025 10:5022 mins
10-11-2025 11:5810-11-2025 12:0024 mins
10-11-2025 12:3010-11-2025 12:36610 mins
10-11-2025 12:3810-11-2025 12:40212 mins
10-11-2025 12:4610-11-2025 12:581224 mins
10-11-2025 13:0410-11-2025 13:06226 mins
10-11-2025 13:1010-11-2025 13:14430 mins
10-11-2025 13:2210-11-2025 13:24232 mins
10-11-2025 13:3210-11-2025 13:34234 mins

Log

17/4/2019 Immersion Heater Replaced
12/4/2019 - Immersion Heater faulty, awaiting plumber
5/4/2017 - 8 SunTech panels replaced with 7 LG panels
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