PV immersion heater proportional control

[lydart]

I also pre orderd and received this email on 1st Feb.

"Hi,


Firstly I would like to thank you for pre-ordering our SolarImmersion Switch Mark III. We are happy to inform you that we will begin shipping of the switches in the third week of February with the intention of them reaching you between the 20th and 25th of the month.


Our SolarImmersion Switch Mark III is a fantastic way to save money and energy, helping not only your wallet out, but the environment too. I would appreciate if you could spread the word about our fantastic pre-order offer to your friends and family so they can feel the benefit of solar heated water too! You could also use the link below to tell your friends about SolarImmersion.


SolarImmersion ? Surplus Solar Energy Water Heater | Tell Your Friends



If you have any questions or would like any more information, please don't hesitate to contact us.



Kind Regards, "

 

[mccltd]

Thanks Lydart,
Well your the second person I know to have received that email.
My problem is they havnt responded to any of my emails and only one phone call. (which was useless)
Just getting a little worried about what happens if you should get a problem, who your gonna call as Ghost busters cant help

 

[vti-chris]

Hi,
I'm new to photovoltaic and water heating and have a Q about it.
I've seen in the net that i need to have different wattage immersion heaters so that when the light is low it will switch to a lower W heater to use the low energy and use all heaters when the sun is on "full" power.
Is there a controller like this offered by any company OR can be made DIY???
(i don't know if this has been discussed before...so i appologise if so!!)

 

[Earthstore]

I have put this before, but I will ask again, Why is everybody obsessed with heating their hot water from excess PV?

Domestic hot water is only 5%-10% of you heating cost, so that leaves 90%-95% which is to heat your home, surly if you are going to the expense of controllers it would make more sense to run some small heaters to reduce your heating costs, this way the sums might add up too.

Once your hot water tank is hot that's it, you still export if you have a surplus, however if you could raise the temperature in your house a couple of degrees that would be more beneficial.

If you owned two cars and there was a device that would save you 50% on your MPG Would you put it on the one that does 20MPG giving you a 10MPG gain, or would you put it on the one that does 60MPG giving you a 30MPG gain?

Before anyone buys a controller, do the mathematics first.

 

[vti-chris]

You mean not to use one at all and rely on gas/wood boiler to heat water up??

 

[Earthstore]

You mean not to use one at all and rely on gas/wood boiler to heat water up??

No that is not what I asked, If you have some free energy IE surplus PV then you should use it, but use it wisely.
Why pay £500 for something that will only save you £50 per year, when if used differently could save you £200 per year.

The figures are not exact of course, they are just examples.
The same as my MPG example, if you only had one device which car would you put it on, the one that gains you 10 MPG or the one that gains you 30 MPG?

 

[Gavin A]

I have put this before, but I will ask again, Why is everybody obsessed with heating their hot water from excess PV?

Domestic hot water is only 5%-10% of you heating cost, so that leaves 90%-95% which is to heat your home, surly if you are going to the expense of controllers it would make more sense to run some small heaters to reduce your heating costs, this way the sums might add up too.

Once your hot water tank is hot that's it, you still export if you have a surplus, however if you could raise the temperature in your house a couple of degrees that would be more beneficial.

If you owned two cars and there was a device that would save you 50% on your MPG Would you put it on the one that does 20MPG giving you a 10MPG gain, or would you put it on the one that does 60MPG giving you a 30MPG gain?

Before anyone buys a controller, do the mathematics first.

presumably because most of the excess generation occurs at the time of year when heating isn't required, and adding electric heaters will add around £3-500 on top of the cost of the Immersun or similar device vs an existing immersion circuit.

We have done both, and in some situations it can be worthwhile to feed excess to a small storage heater eg in a room that doesn't get any sun in the afternoon if the rest of the house is being warmed by the sun later in the day, but it's only really going to reduce boiler use for relatively small periods in the year when just a little supplementary heat is wanted in a single room.

 

[jason121]

I have put this before, but I will ask again, Why is everybody obsessed with heating their hot water from excess PV?

Domestic hot water is only 5%-10% of you heating cost, so that leaves 90%-95% which is to heat your home, surly if you are going to the expense of controllers it would make more sense to run some small heaters to reduce your heating costs, this way the sums might add up too.

Once your hot water tank is hot that's it, you still export if you have a surplus, however if you could raise the temperature in your house a couple of degrees that would be more beneficial.

If you owned two cars and there was a device that would save you 50% on your MPG Would you put it on the one that does 20MPG giving you a 10MPG gain, or would you put it on the one that does 60MPG giving you a 30MPG gain?

Before anyone buys a controller, do the mathematics first.

Kinda disagree
Why not install a TMV and up immersion stat to 70-80 degree
That way immersun will always input into tank

 

[methley]

Yep, that's what I'm doing. However my home built controller was much cheaper than an Immersun anyway. I've also wired in a couple of electric elements to towel radiators also. It's useful to have those hot during the day in summer to dry out towels in the bathrooms. If you don't use it you lose it so why not!

 

[Gavin A]

Kinda disagree
Why not install a TMV and up immersion stat to 70-80 degree
That way immersun will always input into tank

waste of time, effort and money IMO with most cylinders as you'll lose most of that additional heat overnight anyway as the delta T between the tank and ambient air pretty much doubles.

plus it turns a nice simple job into one where you're into messing around with the plumbing around the tank which is usually in a pretty confined space, and opens up all manor of other potential problems once you work out that the isolation valve is buggered etc

 

[methley]

I've also fitted a secondary tank jacket to counteract this. Cost a fiver ;-)

 

[jason121]

waste of time, effort and money IMO with most cylinders as you'll lose most of that additional heat overnight anyway as the delta T between the tank and ambient air pretty much doubles.

plus it turns a nice simple job into one where you're into messing around with the plumbing around the tank which is usually in a pretty confined space, and opens up all manor of other potential problems once you work out that the isolation valve is buggered etc

open the door and warm the hall way

 

[Gavin A]

I've also fitted a secondary tank jacket to counteract this. Cost a fiver ;-)

that's always worth doing, but as an example, we've got a monitored solar water heating system at home with a 50mm insulated jacket, which overnight will drop from 80deg to 70deg C. This isn't really an issue with our system as all the plumbing was needed anyway, but I don't see it being worthwhile most of the time when all you're doing is putting a controller on the existing immersion circuit as it's just opening up a whole different can of worms for minimal benefits and adding at least 50% to the installed cost of the immersion controller.

 

[Gavin A]

open the door and warm the hall way

just what's needed on those hot summer nights....*






*and now I've got John Travolta / Olivia Newton John singing away in my head

 

[Greenday]

Just chatting to a customer who we fitted an immersun for. He turned his boiler off for hot water 4 weeks ago and has enough hot water for his needs since via just the immersun.
The reason for his call was that he wants us to fit an electric heater to the relay. I had to discourage him a little and have asked him to monitor to check that the immersun is showing water hot at some stage during each day!
Must admit I'm surprised he is getting enough hot water at this time of year even if he is a small user.

 

[echase]

Why is everybody obsessed with heating their hot water from excess PV?

Before anyone buys a controller, do the mathematics first.

Here is some maths and some hard facts.

Intelligent Immersion Ltd has done a detailed analysis of several of its proportional controllers that have been in service for more than a year, based on logging their power flows. It is concluded that a fair average figure for energy put into an immersion heater is 1400kWhr per year for 4kW PV systems. Based on a gas cost (plus boiler inefficiencies due to short cycling in summer) of 7p per unit that amounts to £100 per year saved. With oil, bought wood, LPG or full priced electricity that might be double. So with a £200 device price it pays itself back in 1-3 years, not including any installation cost (which should be zero for DIY install). That is an excellent payback for a green device with many, such as double glazing and PV, taking much longer. It would be good even at a base 4p per unit gas cost. That is good reason to be obsessed with water heating.

The biggest reason for not exceeding 1400kWh is because the water temperature on summer days reaches its set temperature part way through the day.

Of course there are things that can be done to extract more than 1400kWh out of it such as heat a towel rail, second immersion, underfloor heating, etc, but 2 problems:-

1. Our data shows that there is only significant excess export from say Mar to Sept and only then on very sunny days, which are pretty rare in UK. That is not the days when you normally want underfloor heating, etc. A towel rail is about the only summertime use for the heat and personally I never need to heat my towel rails in that period. Battery charging is about the only thing I can think of that can be done with any excess year round.

1. It incurs costly additions to the basic immersion application, whose payback will be long as their benefit is small (e.g. due to the short period when they are useful).

So to adapt your car analogy a car that does 60mpg is good. One that does 80mpg is better but not if it costs 50% more to buy, as the extra will never recover itself in saved fuel.

There are some strange claims being made by some in this market area. You can generate very optimistic numbers that lead to marketing statements like “save £250” but only if you assume at least 2 out of 4 of the following factors: 100% of the generation goes into water heating (i.e. no house usage), fuel is >15p, it is a large household using lots of water and is in south of England. It is disingenuous to claim that it applies to all.

For stepped contollers and 1kW immersion elements the payback is much longer.

 

[echase]

1. Our data shows that there is only significant excess export from say Mar to Sept and only then on very sunny days, which are pretty rare in UK.

Just to be clear, by that I meant more export than the immersion can absorb because it is up to temperature or the export is over 3kW. Of course it can carry on powering the immersion all year round, albeit with much less export available to be absorbed in the depths of winter. At the moment it is cold and sunny and my unit is putting 1kW into the immersion. There will though not be enough input over the short day to have any spare for say towelrails, unless I am very abstemious with water usage.

 

[Worcester]

.
The same as my MPG example, if you only had one device which car would you put it on, the one that gains you 10 MPG or the one that gains you 30 MPG?

It depends how often and far you drive each of the vehicles, ....

 

[Worcester]

Here is some maths and some hard facts.

Intelligent Immersion Ltd has done a detailed analysis of several of its proportional controllers that have been in service for more than a year

Here are some more hard facts, available publicly from Companies House

Name & Registered Office:
INTELLIGENT IMMERSION LIMITED
THE GREETINGS
GRANGE ROAD
WINCHESTER
ENGLAND
SO23 9RT
Company No. 08271212
Date of Incorporation: 29/10/2012

Some I'm not quite sure how it can have done 12 months analysis?
Or perhaps Edward Chase, sole director of Intelligent Immersion Ltd was working with and selling his products through a different company?

 

[Gavin A]

I think he's been running and monitoring some pre-production pilot systems for a while, I'm aware of the evolution of his design from concept through to this stage as he basically documented it on the Navitron forum prior to eventually being banned when he commercialised it.

I have no reason to doubt that he has the years worth of data that he says he has, though I do think the savings figures he's supplying look quite high, and probably relate to relatively high hot water consumption levels eg family houses rather than single or 2 people households.

 

[echase]

I have no reason to doubt that he has the years worth of data that he says he has, though I do think the savings figures he's supplying look quite high, and probably relate to relatively high hot water consumption levels eg family houses rather than single or 2 people households.

The first prototype Intelligent Immersion was installed in mid 2011 and was followed shortly by many other prototypes. Some were connected to monitoring systems from late 2011 logging them every 5 minutes. The first production versions were in early 2012 but not in the II name. They are now available under the new company structure so technically you are correct that some of the analysis comes from units not marketed by Intelligent Immersion Ltd but, especially since late 2011, it is essentially the same software and hardware. It’s been improved but, as the method of operation is the same, data from over a year ago is still valid.

If you think I am optimistic then some others are quoting much more than I do. I did the analysis partly because I was concerned about these optimistic predictions and wanted to see where the truth might lie. You are right that a 1-2 person household may get less benefit but not say if they use baths whereas the larger household uses short showers. It is not possible to give a better result without collecting statistics for a large range of houses. Not seen anyone else who has been willing to publish any statistics. It isn’t that easy to do because unless you have a whole year of statistics you have not measured the full annual solar cycle. Our full data set exceeds 1million datapoints.

Navitron don’t like mention of any product that they don’t sell/promote themselves.

 

[Gavin A]

well, I know that our 80 tube solar water heating system (east facing, small 47mm tubes) produces around 1000kWh a year of usable energy, as we've been monitoring it for 3 years, and that's in a house with 4 people.

It equates to around daily showers for 3 people, so I think that 1400kWh is going to be pretty top end.

tbh I suspect that your tanks are probably leaking heat quite badly. The tank we're monitoring loses around 1.5-2kWh a day in heat, and it's got 50mm of insulation - if you're heating older tanks with 25mm jackets then this heat loss is likely to be more like 3-4kWh a day if they're being heated during the day, with most of the use actually being the next morning.

So while I can see that the figures could be right for the actual power going into the immersion, I'd suspect that it's not actually replacing that level of heat input unless the house previously had the tank being heated all day long or something. I certainly doubt that this level of savings could be made in any house with less than 3 people living in it.

ps I've also had similar discussions with another supplier who was making much less possible predictions.

 

[echase]

Gavin

In pre solar days the main loss I would have thought is in short cycling your boiler if you leave it on all the time. It may say fire up for just 5-10 minutes many times a day and in between the on times >95% of the heat in the boiler and pipes is lost/not useful in summer. Most people though may top their tank up twice a day which keeps their water quite hot all day so I can’t see the overall heat loss per day changing a lot, depending on whether it’s heated all day or with one or two top ups. Newton’s Law of Cooling. Have no hard data on this though.

The limitation on a PV water heating system is not usually production of spare export but the ability to absorb it into the tank.

Two of our systems had 2 loose blankets added on top of the normal foam insulation and the temperature in the airing cupboard went down dramatically. On one of these it makes a top up at 7pm if the sun that day is inadequate and has hardly lost any temperature by next morning. This PV controller only inputs about 750kWh to tank as it has a small solar thermal system as well, limiting the amount the immersion can do, and the couple are quite abstemious with water. But as the summertime heating is full price electricity and wintertime is gas, 750kWh represents nearly £100 pa saved so payback is around 2 years. As it’s been in service for 2 summers and actually cost less than £200 for a prototype it has probably recovered all its cost already. The solar thermal system was hardly going to recover its cost in >10 years and will get removed as it has got reliability problems.

Our data is mostly for London and Hampshire. Afraid we don't have any monitoring on systems much further north. Clearly you have less sun in Leeds but there are UK places with more like south west of England. I am not sure where in UK is considered to be average. Solar thermal is quite popular in Scotland I hear.

That could be said to be regional bias but remember that there is more population and probably more PV in the southern half so any averaging of results would be biased towards the south. We use to quote lower figures for energy into immersion until the real measurements came in and it became apparent that most PV systems, at least in the southern half of UK, are well exceeding their MCS predicted figures, e.g. Hampshire is around 50% higher and every 10% extra is more than 10% extra available to the immersion as the house load does not increase.

Whether the payback is 1 or 4 years could be said to be not that important, the important point is that it is much better than almost any other product in the energy saving market, barring draught proofing strip, and so earns more money than leaving it in the building society.

The Immersun tells you the amount of energy saved today. Does it not accumulate this value over a year to tell the annual saving and so are there any figures for this available? Rumored to be a pseudo measurement based on counting the on cycles of the burst firing, rather than a real current measurement into immersion, but this should be quite accurate.

 

[lydart]

I see that the SolarImmersion introductory price has now ended.

Gone up by £50 to £249.

 

[echase]

The Intelligent Immersion costs less than that and there is stock available now for immediate shipment.

 

[lydart]

My Solarimmersion switch (Mk 3) has just been delivered.

 

[Gavin A]

you're asking that question on the public forum.

 

[MicraShed]

^^ It isnt hugely difficult to find the retail price of the Immersun out on t'internet.

I cant say I begrudge paying what I did to have it supplied & installed because its not just a case of paying for the device, the VAT and some chap to drive round to the house and fiddle about losing an hour or so of his life installing it and setting it up.
Its all the associated stuff that goes with that - knowing if i have a problem I have a port of call to discuss it and likely some support.

Its been bitterly cold today here in Granada-land and yet in between flurries of snow its been heating the water up a treat.
Happy?
Oh yes.

 

[Gavin A]

^^ It isnt hugely difficult to find the retail price of the Immersun out on t'internet.

he's asking about the trade price though.

You're being reasonable about it, but some customers seem to not understand the concept of a business needing to pay staff wages and running costs on top of the actual cost of the equipment, never mind the time spent researching the equipment, training staff etc.

 

[infinity]

post removed, sorry was not thinking...

 

[mixit]

I have recently commissioned a 5kw wind turbine.
I requested a device to reduce export of power and they offered and fitted the immersun.
The switch has most of the bells and whistles I wanted but unfortunately my lights flickered to such an extent, when the surplus was being fed into the immersion, that I complained.
The turbine company researched the switch more carefully and decided the device was not really legal as it had no approval, so they want to remove it. This, they say, applies to all burst fire switches.
I checked out as many switches as pos and believe the Solar immersion does not use this system.
It has more or less the same options as the Immersun so I will opt for this if the turbine company agrees with me. Electronics are a bit mind blowing.

I believe it is essential to have at least 2 circuits to switch to, however what I would really like is a device which can remotely, via the ring main, switch on a selection of loads with sensing switches using various frequencies.
This would allow loads drawing from a ring main to take power when it is available or in rotation.

Regarding the immersion heater, If I cant find the remote switching I propose to EXTRACT heat from the tank when it is fully hot by running a selection of radiators through the indirect coil. This will cool the bottom area and the power will be redirected to the tank to replenish it. The pump would run when the relay diverts to the second service.
If anybody sees a flaw in this please advise.
MOST especially, if there is an electronics wizard out there will he direct me to a remote switching product.
Perhaps the switch manufacturers who read and contribute to this discussion could consider adding this to their product.

 

[echase]

I believe it is essential to have at least 2 circuits to switch to, however what I would really like is a device which can remotely, via the ring main, switch on a selection of loads with sensing switches using various frequencies.
This would allow loads drawing from a ring main to take power when it is available or in rotation.

Regarding the immersion heater, If I cant find the remote switching I propose to EXTRACT heat from the tank when it is fully hot by running a selection of radiators through the indirect coil. This will cool the bottom area and the power will be redirected to the tank to replenish it. The pump would run when the relay diverts to the second service.
If anybody sees a flaw in this please advise.
MOST especially, if there is an electronics wizard out there will he direct me to a remote switching product.
Perhaps the switch manufacturers who read and contribute to this discussion could consider adding this to their product.

The Intelligent Immersion model i2 will do your basic function without flicker but we can’t do the extras that you ask for with the standard product. Certainly can look at it but I suspect that it would add so much to the price of any product that it would not be cost effective in terms of payback. It’s the law of diminishing returns in that the basic function of one immersion is very cost effective but every extra load that you set up to be fed is less and less beneficial in terms of the cost of providing the function versus the electricity saved/used.

It strikes me that 2 output controllers have some design compromises in terms of the way the second load is triggered, like time delays before it is switched in and back again. You have to make some big assumptions when setting the timings. This results in significant time periods when the generated electricity is being exported or redirected to the wrong load. Would not a simple tank thermostat, that switches over to the second element when the top half is hot, do the function better?

I have taken some flack on forums for pointing out the flicker problem with burst fire devices so it’s good to see that some others do agree with me.

 

[Earthstore]

What about a heat escape radiator plumbed into your hot water cylinder, basically when your cylinder is up to temperature the hot water would circulate through a radiator.

Just a thought.

 

[GOL]

@mixit - there are many instances where light flickering is only the visible effects of such load switching devices available in the market. Majority of which require hard-wiring and citing in and around the consumer unit, hence why some installers will not touch these products with a barge pole.
Your turbine company is correct in their conclusion that the method of Burst Fire TRIAC is not particularly "legal" in any circumstance, due to the method in which the devices proportionally control resistive loads.

No doubt, I feel there is a gap in knowledge available to the marketplace regarding the particulars in how these products work and whether they actually comply to all of the domestic regulations outlined. Hence, I feel these forums are an excellent way for people to come together, learn and understand more about the products available and how best to go about saving energy!

Unfortunately, some of these market products have a very short-termist perspective in their lifeline. I personally believe they will eventually be looked at more closely, in a dim light by DNO regulators and energy suppliers. However, that is not to say that all devices can be painted with the same brush.

The idea to monitor and manage loads within a household is really the next step for any micro-generation system. The immersion has received a lot of attention as this is a prime candidate, being able to store that energy generated as hot water to make use throughout the day - a no brainer! However, not all households have immersion tanks..

Do not forget, this is not the only electrical appliance available in the household!!

 

[danesol]

So apart from the cost deferential, what are the advantages if any, of the Immersun unit over say the Solar immersion mk3 Switch for example ??

 

[echase]

require hard-wiring and citing in and around the consumer unit, hence why some installers will not touch these products with a barge pole.

Don’t understand the problem. Installation in that position is really simple unless there is no space there. PV installers are usually wiring in that region so adding a diverter is a trivial extra task. A totally plug in solution using 13 amp plugs might be easier but few immersions uses 13A plugs so hard wiring is needed. I’d not trust a 13 plug/socket to pass 13A reliably long term so I’d not supply such a product. E.g. how do you know the customer's socket is not in poor shape?

Current distortion is a problem for the DNOs because of all the many switched mode supplies (SMPS) in service. SMPS tend to consume most of their current in the 60-100 degrees phase angle region as per:-

https://www.electriciansforums.net/attachments/harmonics-pdf.120358/ Section 1.4

Power factor - Wikipedia, the free encyclopedia Section Non-sinusoidal components

which show a short triangular current spike centred on 70-80 degrees

A phase angle controller, when at other than full or zero power, on average consumes its power later than 90 degrees and it’s not as spiky as for an SMPS, unless at low powers (>120 degrees) when the spikes are not that high anyway. Phase fired controllers - Wikipedia, the free encyclopedia So it’s filling in the gap in the last half of the SMPS’s cycle.

Therefore if I were a DNO I’d quite welcome some phase controlled devices onto the supply to compensate for SMPSs or at least be ambivalent about it. It’s not perfect compensation and so I’d not recommend a street full of phase controlled diversion boxes, but I don’t see a problem with a few. There is no adverse effect on the rest of the electrical devices in a property or in its neighbours, unlike with burst firing, as long as a decent EMC filter is used. It’s only the DNO that might notice some distortion if there were too many of them.

A PWM device is one solution but they will be expensive and you have to have a screened wire between the device and the immersion due to the very high switching speed of the PWM that causes this wire to radiate EMI. In my house it is well nigh impossible to access this wire to change it and in almost any house this will involve significant work. So it will add a lot of cost.

 

[danesol]

echase - any comment ??

So apart from the cost deferential, what are the advantages if any, of the Immersun unit over say the Solar immersion mk3 Switch for example ??

 

[echase]

echase - any comment ??

Sorry, nothing to do with me. Not our units. All I can say is that the Intelligent Immersion is well proven, reliable and does not use burst firing. And cheaper than many.

 

[danesol]

Sorry, nothing to do with me. Not our units. All I can say is that the Intelligent Immersion is well proven, reliable and does not use burst firing. And cheaper than many.

Which btw are yours ( Ive assume solar immersion ) ??

and what others are there as personally I only know of 3 units which do this - all completely different prices and all not wanting to explain how they stop flickering - lol

 

[danesol]

Thank you for the info its given me 1 more reason to buy the Vauxhall Ampera

Great car btw