iboost/Eddi vs Immersion timer

[J Hunter]

I have recently had solar panels installed and the contractor is recommending a diverter for the immersion heater so I can use the solar panels to heat the water - particularly in the summer.

With the remote digital display and installation this comes to about £500.00.

My question...... for about £30.00 (plus installation costs)could you not install an Immersion timer with overide/boost facility which would give you more or less the same result without the large cost??  

Just dont feel I will ever recoup £500.00 on my immersion - I expect in the winter we will have to revert to heating our water with oil.

I would appreciate any thoughts - what will I gain for another £400???

Thank you

[JohnMo]

The timer will use 3kW per hour no matter what you PV output is.  So if your generating 1kW, you will be paying for 2kWh.

 

The diverter only sends any excess to the immersion. So if your generating 1kW and using 800W, only 200W will go to you immersion.

[ProDave]

I generally estimate that about 1/3 of the PV I generate ends up in my immersion heater via the PV diverter so at todays price about £175 per year.  So at your price 6 year payback for the diverter.

 

It all depends if you are on a tariff that pays you for export if it is worthwhile or not.

[SteamyTea]

12 hours ago, ProDave said:

I generally estimate that about 1/3 of the PV I generate ends up in my immersion heater via the PV diverter so at todays price about £175 per year. 

Much of it depends on how much DHW is used.

 

I use about 30 lt a day, other may use 200 lt.

[JohnMo]

My Solic200 cost £144.  I am displacing gas consumption, and have around 2 to 3 year payback.

 

Not sure why you are paying £500, get the basics, does what it says on the tin, nothing more or less.

[Gone West]

I fitted a Solar iBoost a few months ago and it was £300. I think they have gone up in price since then. I was exporting most of what we were producing, and using oil to heat the water, but now a lot goes to heat the DHW tank.

[AliG]

I have started to look into getting the Eddi.

 

In my case we have 3 phase and it seems like the only system that can measure export on three phases, using the Harvi add on.

 

I also have Octopus Intelligent, currently fixed at 7.5p during the night, so this water I can save money by using night time electricity rather than gas to heat my hot water.

 

I had the opposite thought, which is that I can put the cost of the timer towards a PV diverter.

 

If I didn't need the three phase capability I would get a Solic which is a lot cheaper at just over £200.

 

I have not had a smart meter for a full 12 months yet, but it looks like I will export maybe 900-1000kWh over a year.

 

I guess the sum you need to do is -

 

Export kWh x Offset cost of gas for water heating

 

Minus 

 

Export kWh x possible export payments.

 

and then look attached this relative to the cost of the diverter. @ProDaveI think you are maybe on the FiT scheme, otherwise you ned to subtract export payments from the benefit. I think Octopus Agile Outgoing has actually been paying higher export payments can the price of gas recently, so you could sign up for that instead of a diverter (I cannot as you cannot get these higher payments if you are on an Octopus Go type plan)

 

So if you are set on exporting around 1000kWh a year, then you are going to have a net saving of around £100 at the next price cap. However, if gas prices settle back to longer term averages in a few years the saving could be quite marginal. 18 months ago gas cost less than the payment I could have got for exported electricity.

 

My case is a little different as I reckon we use around 15000kWh a year of gas to heat hot water. By heating my hot water overnight using Octopus from October, before my fix is up, I could save £375. Annoyingly the Solic does not have a timer.

 

So I would have around £500 for an Eddi and a Harvi covered by year 1 savings.

 

[JohnMo]

I think like me https://forum.buildhub.org.uk/profile/8-prodave/ is a self install, so no payment for export.

[ProDave]

16 minutes ago, JohnMo said:

I think like me https://forum.buildhub.org.uk/profile/8-prodave/ is a self install, so no payment for export.

Yes mine is self install so no MCS and no export payment = I don't want any export.

 

The Octopus Outgoing tariff will change the equation for some, but I believe that still needs an MCS install?  and it needs a smart meter, something I am resisting as long as possible.

[Ferdinand]

45 minutes ago, ProDave said:

Yes mine is self install so no MCS and no export payment = I don't want any export.

 

The Octopus Outgoing tariff will change the equation for some, but I believe that still needs an MCS install?  and it needs a smart meter, something I am resisting as long as possible.

 

Yes it needs the installation certificate number, or certificate, which they check against the register.

 

And they also ask for the "DNO letter" which informed the DNO, and the DNO response. They say these smooth the way for what is quite pioneering.

 

I don't think I have a copy of the DNO letter as it was all done by my supplier as part of the deal, so would need to consult. 

 

I think I will be plumping for Octopus Outgoing Agile once I have reflected a bit more and asked some more questions.  

[AliG]

7 hours ago, Ferdinand said:

I don't think I have a copy of the DNO letter as it was all done by my supplier as part of the deal, so would need to consult. 

 

Yes, I have run into this. I have an MCS install, but I have the letter they sent the DNO, but I do not have the DNO's response letter. I emailed the DNO asking for it and got no response.

[Ferdinand]

19 hours ago, AliG said:

Yes, I have run into this. I have an MCS install, but I have the letter they sent the DNO, but I do not have the DNO's response letter. I emailed the DNO asking for it and got no response.

 

Did that cause problems with implementing the charge of tariff?

 

Thanks

[AliG]

1 hour ago, Ferdinand said:

Did that cause problems with implementing the charge of tariff?

I have an MCS system but it was installed after FiTs.

 

Because it is 3-phase I couldn't get a smart meter to see my exported electricity, so couldn't sign up for export payments.

 

Now that I have a smart meter I still cannot get export payments as Octopus want the DNO letter which I don't have.

 

I suspect the way around it is to apply again to the DNO, ut it is quite a faff.

[Ferdinand]

2 minutes ago, AliG said:

I have an MCS system but it was installed after FiTs.

 

Because it is 3-phase I couldn't get a smart meter to see my exported electricity, so couldn't sign up for export payments.

 

Now that I have a smart meter I still cannot get export payments as Octopus want the DNO letter which I don't have.

 

I suspect the way around it is to apply again to the DNO, ut it is quite a faff.

 

Tx. I may try and see what happens.

 

I have a 2015 email from my PV installer saying they will be informing DNO.

 

But installer is now in scaffolding.

[AliG]

Having looked at this I think I am just going to install an immersion timer.

 

I have looked at my export of electricity and I won't even make 1000kWh in a year.

 

If I assume I can get an export payment of around 5p versus gas cost of 5-10p long term (more in the next year I know) then I can only save maybe £50 a year.

 

Also it seems that these devices often burn out due to having 3kW going through them for hours on end.

 

But I can save a few hundred in the next 12 months using Octopus to heat my water overnight with a £50 immersion timer.

 

Any recommendations for an immersion timer that is robust and won't burn out after a few months?

[Radian]

1 hour ago, AliG said:

Also it seems that these devices often burn out due to having 3kW going through them for hours on end.

 

That's interesting, where can I read about that?

[AliG]

I just see a lot of people saying in passing that they have had devices burn out.

 

I don't have any stats unfortunately. If you look at the immersion timers on Amazon there are quite a lot of one star reviews where they have broken after a year or less. The other problem on Amazon is that loads of people review things after a few days which doesn't tell you anything about their longevity.

 

For me considering the small saving for export use and a 5-10 year payback period on an Eddi, it just doesn't seem worth it.

[SteamyTea]

9 hours ago, AliG said:

Any recommendations for an immersion timer that is robust and won't burn out after a few months?

This is what I use on my immersion heater, and my storage heaters.

Bought them in 2013, not had a problem.

https://www.amazon.co.uk/gp/product/B0066NEBO6

[MikeSharp01]

2 hours ago, AliG said:

I just see a lot of people saying in passing that they have had devices burn out.

Two of ours have - the current (no pun intended) one seems to be standing up to the load though.

[Radian]

1 hour ago, MikeSharp01 said:

Two of ours have - the current (no pun intended) one seems to be standing up to the load though.

That's not good then. These things ought to be able to last for decades. It would take some serious corner-cutting to get them to the point of near-failure (the point where most low-end products are designed to operate at). Would love to see a teardown analysis. Don't suppose you've peeked to see what failed or still have one I could buy off you?

[MikeSharp01]

6 minutes ago, Radian said:

Don't suppose you've peeked to see what failed or still have one I could buy off you?

I did keep them but sadly have thrown them away in a clearout last year. One had a blown relay the other just stopped showing anything on the screen and if the wedded bliss is to be maintained its straight down to screwfix and get another without worrying about why it's bust. 

[Radian]

2 minutes ago, MikeSharp01 said:

if the wedded bliss is to be maintained its straight down to screwfix and get another without worrying about why it's bust. 

 

I know that pressure and the look that goes with it 😀

 

It really messes up the calculations when you look at the numbers, although I always used to say something along the lines of "you can get an awful lot of energy for £x" but that's no longer necessarily true. It makes the one year statutory guarantee absolutely useless when considering how something needs a good few years operational lifespan to pay you back.

 

But this solar PV->immersion divert business is ripe for some disruption. Looking at the price trend over the last few years it looks to me as though divert manufacturers are price gouging due to the energy crisis. At a guess, the parts needed to build something like my home brew design could be bought for under £50. The main thing stopping me putting into production through the manufacturing service I use for my commercial stuff is the red tape associated with the EMC directive. That and the fact that I have no marketing branch that hangs over the home energy sector. On the other hand, items sold as kits are an altogether different proposition. My head tells me not to get involved but my heart feels for those faced with this dilemma.

 

One possible approach is that, without looking, I would expect a chinese rip-off eddi to exist with a ticket price of a shade under £100. It'd be awful and might start a fire but could be a starting point for a conversion kit. Anyone spotted anything like this?

[SteamyTea]

11 minutes ago, Radian said:

That and the fact that I have no marketing branch that hangs over the home energy sector

You find someone that does. 

But choose carefully.

[MikeSharp01]

1 hour ago, Radian said:

That and the fact that I have no marketing branch that hangs over the home energy sector.

But you do have Buildhub - although non commercial loads of people come here to get great ideas.

 

I have been thinking along the same lines about how the market we are in sees the UK as treasure island. If its going to be sold direct in the UK the price will be X while elsewhere you can get it at X-significant chunk of money and because importing is not well understood people don' do it. Some of it is about our lack of the 'delayed gratification' Gene but I suspect most of it is about being uncertain when buying from France / Germany / China direct what the admin needs are. Basically none really, although that may change if we put up barriers.

 

What is needed to get EMC compliance signed off these days - big grey box no use here I suppose? This might be worth a read: https://www.ul.com/insights/ten-things-know-successful-smart-home-product-launch from UL, one of the bigger test houses so watch for bias, but not all about just EMC.

[Miek]

2 hours ago, Radian said:

That's not good then. These things ought to be able to last for decades. It would take some serious corner-cutting to get them to the point of near-failure (the point where most low-end products are designed to operate at). Would love to see a teardown analysis. Don't suppose you've peeked to see what failed or still have one I could buy off you?

I had a 3kw tank thermostat (30l zip water heater) fail. It was down to the spade connectors on the wiring loom causing a point of high resistance which then produced excess heat ( to the point where the pastic was going brown) and eventually failed. I soldered the replacement one on to try and mitigate the problem, so far so good...