17°C
Porth, Newquay, Cornwall. UK
Updated04/09/2025 18:30 
 




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 04-09-2025 18:40
Threshold - Spring 3100 W
Current Output 407 W
Peak Output 3623 W
Last Update 04-09-2025
Meter # 5144.63
Days solar 2765
Days Gas 1604
Aprrox Savings Gas ## 2765 days @37p = £1,023.05
# Meter since 29th June 2013, updated most days
## Approx saving on gas,averaged 37p per day


Immersion Data
Date/TimeThresholdOutputAction
04-09-2025 09:48 30003018ON
04-09-2025 09:52 30001239OFF
04-09-2025 09:54 30003570ON
04-09-2025 09:58 30002423OFF
04-09-2025 10:06 30003159ON
04-09-2025 10:12 30001598OFF
04-09-2025 10:14 30003459ON
04-09-2025 10:18 30001068OFF
04-09-2025 10:38 30003478ON
04-09-2025 10:46 30002124OFF
04-09-2025 10:50 30003614ON
04-09-2025 10:52 30002229OFF
04-09-2025 10:56 30003492ON
04-09-2025 11:10 30002268OFF
04-09-2025 11:18 30003424ON
04-09-2025 11:26 30002715OFF
04-09-2025 11:28 30003290ON
04-09-2025 11:34 30001311OFF
04-09-2025 11:38 30003292ON
04-09-2025 11:42 3000633OFF
04-09-2025 11:44 30003615ON
04-09-2025 11:54 30002986OFF
04-09-2025 12:04 30003621ON
04-09-2025 12:06 30002773OFF
04-09-2025 12:08 30003279ON
04-09-2025 12:10 30002307OFF
04-09-2025 12:26 30003127ON
04-09-2025 12:28 30002341OFF
04-09-2025 12:30 20003238ON
04-09-2025 12:32 2000906OFF
04-09-2025 12:40 20003617ON
04-09-2025 14:04 2000562OFF
04-09-2025 14:08 20003566ON
04-09-2025 14:16 20001609OFF
04-09-2025 14:18 20003400ON
04-09-2025 14:36 20001667OFF
04-09-2025 14:42 20002290ON
04-09-2025 14:44 20001713OFF
04-09-2025 14:54 20002486ON
04-09-2025 15:04 2000543OFF
04-09-2025 15:08 20002607ON
04-09-2025 15:10 2000638OFF
04-09-2025 15:58 20002538ON
04-09-2025 16:02 2000566OFF


Immersion Time
Date / Time ONDate / Time OFFTime ONTotal Time On
04-09-2025 09:4804-09-2025 09:5244 mins
04-09-2025 09:5404-09-2025 09:5848 mins
04-09-2025 10:0604-09-2025 10:12614 mins
04-09-2025 10:1404-09-2025 10:18418 mins
04-09-2025 10:3804-09-2025 10:46826 mins
04-09-2025 10:5004-09-2025 10:52228 mins
04-09-2025 10:5604-09-2025 11:101442 mins
04-09-2025 11:1804-09-2025 11:26850 mins
04-09-2025 11:2804-09-2025 11:34656 mins
04-09-2025 11:3804-09-2025 11:42460 mins
04-09-2025 11:4404-09-2025 11:541070 mins
04-09-2025 12:0404-09-2025 12:06272 mins
04-09-2025 12:0804-09-2025 12:10274 mins
04-09-2025 12:2604-09-2025 12:28276 mins
04-09-2025 12:3004-09-2025 12:32278 mins
04-09-2025 12:4004-09-2025 14:0484162 mins
04-09-2025 14:0804-09-2025 14:168170 mins
04-09-2025 14:1804-09-2025 14:3618188 mins
04-09-2025 14:4204-09-2025 14:442190 mins
04-09-2025 14:5404-09-2025 15:0410200 mins
04-09-2025 15:0804-09-2025 15:102202 mins
04-09-2025 15:5804-09-2025 16:024206 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