Immersion Heater Powered off Solar Panels

[Vaughan1]

I have a 4 kWp solar system which feeds into my domestic consumer unit and associated meter.  I also have a separate consumer unit connected to an off-peak meter which is used only for an immersion heater.  I would like to transfer the immersion heater to the domestic consumer unit to take advantage of the solar electricity.  I plan to simply use a timer and possibly a 110/230 volt transformer (if I can find one small enough to fit in the airing cupboard without over-heating!), to partially match the immersion heater demand with the solar output.  However, I would like to keep the option of using the off-peak electricity for the immersion heater in the winter when the solar output is low.  One possibility would be to wire in two sockets into the airing cupboard: one off each circuit: but looking through other blogs, this seems to be bad practise because 13A plugs are not intended for long use at 3 kW especially in a damp airing cupboard (the heater is 13 kW at 230 v which is just 13 A, but would be much lower if I fit the transformer).  Also I think that sockets should not be connected on off-peak supplies.  Another option would be to put a junction box alongside the consumer units and hard wire this to either consumer unit since I should only need to change over twice a year.  Ideally, some sort of change-over switch that allowed me to swap between supplies would work, but I am not sure if such a thing can be used in this situation. I would appreciate any suggestions.

[Davo]

I did a similar thing when I had a low and high power immersion in my tank.

I used a 2 pole change over switch. My arrangement switched the live and neutral from one immersion to the other immersion.

Yours would work in reverse - 2 feeds in and the immersion off the common.
I bought my switch from screwfix for about a fiver. As these need to rated at at least 13A the only option I could find was a metal cladded one. It was tucked away in the airing cupboard - so it didn't matter

[Vaughan1]

Thanks Davo.  Sounds like a very neat solution.  Have you got the Scewfix part number as I struggled to find it?

[Davo]

Hi Vaughan1
I may have been mistaken about mine being a 2 pole change over switch (it was a long time ago). I can't find one on screwfix either. Maybe I just switched the live (which wouldn't be suitable for you).

You could use something like this from eBay though. A 3 pole rotary changeover switch at £11. It's rated at 25A (a wee bit over the top) and would need to be mounted in suitable box etc but would be a very professional solution. I suspect you could fix it next to your consumer unit etc

http://www.ebay.co.uk/itm/25-Amp-3-Pole-Rotary-Change-Over-Switch-On-Off-On-/180800786058?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item2a18910e8a

There maybe other cheaper 2 way ones available as well - but that was the first one to pop up on a google search
Your local electrical wholesaler will have a range as well (not quite so cheap normally - unless you are a contractor)

[billi]

Come on Guys  ,its just  four wires  you need to connect ,do not be so dully and make a big deal  out of this connection 

Buy a couple of PV panels  and a DC immersion ,simplest   .........

A friend  showed me how he manages so slow his  el. meter down,  i actually saw  it turning slower



Fascinating ideas here , in  how to use more electricity ,but pay less

I  guess ,that is  what a renewable Forum is for   



 

[Jober]

Don't see why some of you are against using PV electric to heat water. We have to pay for heating up water, be it electric, gas or oil. As both gas and oil are costing the earth, using excess PV is the answer.