Intelligent Switch Question

greyteam1959

Might seem a daft question to those of you that know the answer !!
When they say 'uses surplus PV power' does this mean that if your PV generation at a certain point in the day is say 1.7 Kw & your house is consuming 700w at that point the 'surplus' power of 1000w is switched to your immersion heater ???

We consume very little electricity during the day as there is nobody at home so an intelligent switch would seem on this basis to be a good idea for us ???

Am I correct ??

Martyn1981

Hiya, will depend on costs and savings, which in turn will depend on the product you buy, and the fuel you'll be displacing. Try this thread:

https://forums.moneysavingexpert.com/discussion/4152489

A few people have them and are starting to put some numbers together (Sly Dog Jonah for example). The crucial factor will be how well they perform in the sunnier 6 months of the year.

Mart.

Cardew

Yes you have it correct.

However is you have gas or oil, you need to price your savings at the cost of gas/oil - and take into account the efficiency of boiler.

There are threads on this subject and you need to weigh up if the cost of buying and installing the appliance is justified by potential savings.

Some people who have fitted the immersun are posting the kWh diverted to the immersion.

greyteam1959

I just needed clarification regarding the 'surplus power' bit !!
As most of my gas consumption is for the heating of hot water an intelligent switch would seem to me to be a good idea.
Or course the cost & potential saving would need to be looked at.

Many thanks.

Hobbo2006

mervyn11 wrote: »

Might seem a daft question to those of you that know the answer !!
When they say 'uses surplus PV power' does this mean that if your PV generation at a certain point in the day is say 1.7 Kw & your house is consuming 700w at that point the 'surplus' power of 1000w is switched to your immersion heater ???

We consume very little electricity during the day as there is nobody at home so an intelligent switch would seem on this basis to be a good idea for us ???

Am I correct ??

Yes you're correct in your thinking. The immersun and the mark 3 solar immersion switch are proportional so will divert as little as 10w of excess generation, if that's all the excess there is at the time. I have the immersun as I was eager to get one installed at the back end of the "summer". You have time to make a decision as this gadget won't do anything significant until March at the earliest.

A key factor for me was that we have people at home during the day , so the automatic nature of the proportional switches was necessary due to the mrs putting washing on and kids watching TV etc, although that's where the higher cost of the product comes in.With nobody at home you could do the same with much less intelligent, and therefore cheaper, products and realise the savings more quickly. Having said that I do feel safer that the product was been fully certified for commercial sale rather than DIY.



The payback on the Immersun is around 3 years for me as my hot water is provided 100% by the immersion element and therefore expensive. It would have been about 2 years with the mark 3 solar immersion switch.


Would be great to hear what you decide and any figures once installed.

supastar42

I have a new system that was installed on 9 Jan. I had an immerSUN from the start and it has run continuously apart from needing a replacement, so wasting a few days. In two months my system has generated 206 units and the immerSUN has exported 78 units. So virtually all the units I have ever had generated, have been used. My base load is around 300 watts. In the summer I expect the immerSUN to provide all my hot water needs. I have a large tank (210L) for two people and by heating it to 80C I will have a nice heat buffer. A much better bet than having solar thermal installed.

My system. Oxford. 14 x 260 watt panels in two strings, 6 and 8, due to shading. 45deg roof, SSE facing. Samil two string inverter.

EricMears

I wanted to add a report about my Optiplug and this topic seems more appropriate (and a lot less cluttered) than the mentions it has had in the 'My Generation' thread.


As previously mentioned, Optiplug arrived in bright sunshine but sky clouded over before postman got to end of road then we had three days with virtually no sun. Testing therefore had to be postponed.

Initially very disappointed. Optiplug just wouldn't pair with my Wattson transmitter. However, I can't praise 'Energeno' enough: they realised that my 'old' (I bought it secondhand about 18 months ago but it can't have been very old when I did so) transmitter was an early model which isn't compatible with the Optiplug so they sent me a modern replacement without charge.

I don't suppose they'll do that for everybody so if you are considering an Optiplug, don't count on it working if it is fitted with a red aerial wire; modern ones have a white aerial wire. If you haven't already got a Wattson, they're on offer at the moment for just £125 or you can buy a transmitter (without the display unit) for £50 - but you'll still need at least two (possibly more) measuring heads.

Since then it's been working my immersion heater just fine. Unlike the Immersun & its 'cousins' , the optiplug only switches a device ON if it thinks there's enough free power to run it or OFF if you'd have to buy any. It wouldn't therefore be a lot of good with a 3kW immersion heater as you'd practically never see that much free electricity. Devices that divert just the free amount of electricity to an immersion heater cost a lot more than the Opiplug's £50.

My immersion heater wiring has been modified to run via a site transformer which drops voltage at heater to 115V and hence derates heater to 750W - a figure that is often available from my generation excess. I've only finally got the thing working today but it seems to be working as intended.

I've also bought another one (Energeno sent it along so that I could test whether first one was indeed faulty. I decided to buy it rather than return it) which I'm using to run my 600W 'caravan kettle' . That too seems to be working as intended.

silverwhistle

You talk about 3kw immersion heaters but I seem to recall that many tanks were designed with two potential immersion installation positions, particularly with cheaper rate night electricity in mind: a large immersion and a top up one to use with day rate. It's been some years since I lived in the Uk or been in my own house, so perhaps my memory is failing me!?

Would a smaller, say 1kw (240v) immersion be a reasonably productive solution?

legoman62

silverwhistle wrote: »

You talk about 3kw immersion heaters but I seem to recall that many tanks were designed with two potential immersion installation positions, particularly with cheaper rate night electricity in mind: a large immersion and a top up one to use with day rate. It's been some years since I lived in the Uk or been in my own house, so perhaps my memory is failing me!?

Would a smaller, say 1kw (240v) immersion be a reasonably productive solution?

You could use a 1kW immersion.. I have. Obviously takes longer to heat up, but using energysavingexp's (from a forum on this site) excellent device, I can produce enough hot water from April - Sept + to turn my gas off.
I do get some HW in the winter months but need the boiler to back up.

I also changed my old copper cylinder for a new stainless steel one.
It has a connection at the top for a standard 21/4 immersion, with a spare 22mm connection on the side. When I had the tank fitted I made provision to fit another immersion in the bottom as well as the side by modifying the drain p/wk but, non standard immersions are very expensive so have not pursued this. Another option I considered was to put (weld) a 21/4 boss in the side of the cylinder to accept a standard immersion. TBH I am getting enough hot water for our needs without this:D

[Deleted User]

Is it true that an ImmerSUN [at £350 inc VAT] in the real world would take approx 5.8 years to pay for itself for average hot water use? That's my back of a fag pecket calcs. Seems high... Am I wrong?