#1 Oct. 22, 2013 20:34:00

rogerhoward
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The Intelligent Immersion


Having been put on an old thread http://www.microgen-database.org.uk/forums/general-discussion/export-meters?pn=3 and then so quickly “bumped”, this was probably missed by folks.


Keith said that the Immersun which has recently attracted attention, in fact has a high reported failure rate. He reported that by contrast he's has for 18 months instead the cheaper “Intelligent Immersion” http://www.intelligent-immersion.co.uk with no issues, and good customer service too.


Does anyone else have experience of the “Intelligent Immersion” ?







Economy 10 tariff provides 6.9p/kWh off-peak import between 12am-5am, 1pm-4pm and 8pm-10pm; http://www.pvoutput.org/aggregate.jsp?id=21047&sid=18934&v=2&t=m on approx. 63% off-peak usage, 22% solar usage, and 15% peak-rate usage.
1,900kWh annually is exported, mostly in summer, on approx. 3,200kWh generation. Approx. 4,500kWh/year is imported, mostly for (a) winter and springtime off-peak Storage Heaters, and (b) off-peak hot water Immersion heating (which is “dumb”, i.e. not linked to the solar PV).
PV array is split East-West. Income is from Phase II 21p/kWh Feed-in-Tariff plus smart metered 3.2p/kWh Export Tariff.

Edited rogerhoward (Oct. 22, 2013 20:34:00)

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#2 Oct. 24, 2013 14:01:00

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Roger,


Just to qualify what I reported on the export thread.


Before I purchased a proportional controller I did a lot of research and spoke to all the suppliers that I could find of this class of device.


As I upload both live generation and consumption to PVOutput, I found a way of ordering other users data (who don't hide consumption) which showed me who was using proportional controllers. I would contact the users and ask them what brand of device they were using, how reliable it was, and would they recommend it. Combining this information with the live traces that these devices were producing on a daily basis, it was possible to determine which devices were worth exploring further and which were not.


My research showed that even when using a proportional controller, if the device in use was not capable of keeping up with rapid changes in generation due to variable cloud cover, or changes in house load (kettle etc) then some of the devices being sold would import electricity for a period whilst the device caught up. This of course is not an ideal scenario as the whole point of using a proportion controller is to minimise both export and import. It became apparent very quickly that not all devices were equal in the level of processing power, sampling frequency and the number of discrete steps that were employed to adjust the power levels sent to the Immersion. It is also evident from looking at the live traces that these devices produce, that some manufacturers attempt to compensate for this lack of processing speed/sampling/switching by leaving a larger buffer of continuous export to the grid. This can result on a variably sun / cloudy day that these systems still export over 20% of the daily generation, which makes a big difference over a year. Typically you want a device that exports the minimum amount to the grid whilst diverting the maximum to the immersion, and is capable of altering the immersion load quickly enough to prevent any import from the grid. 


I eventually settled for the Intelligent Immersion because of the fact that it typically only exports 30 watts, has hundreds of discrete power steps, has very fast sampling rates and calculates accurate power conversion factors throughout the day, it is also one of the cheapest devices on the market. In addition the users who I contacted who have this device, have never experienced a failure, nor have a bad word to say about either the device or the company that manufactures it. This was not the case for some of the other manufacturers and in particular the one I mentioned. In some cases users had experienced multiple failures after having the device replaced more than once, and were now looking for their money back.


During the eighteen months I have had the my Intelligent Immersion device, I have had the GAS boiler off between the end of April and (mine is still off as of 24th October) and October, only on a very few occasions have a I had to fire up the GAS boiler to provide hot water, when we have had two or three days without any sun. In our household there are 4 adults so that is not bad going. In total this year I have generated over 3700Kw and have only exported 191kw (which is when I went on holiday and had the device turned off). As discussed on the Export thread I do have an automatic pumping solution to ensure I heat all of my hot water cylinder, and never export to the grid.


I am not a big fan of giving recommendations online but I can highly recommend the Intelligent Immersion device, and the support the company offers. You will be pushed to get a device that equals it in performance and reliability for such a low price, which makes it from my point of view highly desirable indeed.


Though as always do your own research.


Regards Keith


 











Edited default (Oct. 24, 2013 14:01:00)

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#3 Oct. 27, 2013 16:02:00

SteveRogers
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The Intelligent Immersion


Hi Keith,


Thanks for the useful posting and I note your comments about immersun.


I note from the other thread that you estimate you are saving the equivalent of about 5,000 kWh of gas by using a proportional immersion switch.  On the other hand, you are now using around 3,600 kWh of your production.  Of course, some of this (20% I guess) will be used on other household activities so let's say you are using 2,900 kWh on heating water in your tank.


There are two points I conclude from this:


1. Using your gas boiler for 2 hours a day to heat water was probably overkill (though need to take into account the efficiency for heating water in this way to make a proper judgement as there will be losses in the boiler heat exchanger and pipework)


2. This seems to make a strong case for the “greenness” of using personal PV production with an added immersion switch.


Am I being too simplistic here?  I guess in the global sense you have to take into account the efficiencies both of heating water and converting gas to electricity too.  At the personal energy balance level though, it would seem to make a strong case for immersion switching.


Since I use an oil boiler to heat my water tank (for 2 hours a day) I am rapidly being persuaded to cast off my “green prejudices” and go for an Intelligent Immersion switch!


Steve








Edited SteveRogers (Oct. 27, 2013 16:02:00)

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#4 Oct. 27, 2013 17:25:00

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The Intelligent Immersion


Hi Steve,


Yes you assumptions look valid. My GAS heating was actually programmed to come on twice a day for 2 hours before I got the intelligent Immersion, so this was very wasteful. The best thing I did initially was to fit cheap LCD temperature sensors across the length of the tank this gave me an accurate picture of the water temperature in the tank and how it changed with usage etc.



My GAS boiler is relatively new and is efficient, however, the piping to the hot water cylinder which is about 25 meters away and run under an extension floor are not insulated. Therefore as I cannot get to insulate these pipes without a lot of hassle I guess my overall efficiency is not so good, and the losses quite high heating my water via GAS.



To me heating my water with electricity I am generating myself is appealing as an immersion is near 100% efficient. Though, as I explained above, not all the immersion switching devices are equal.



You also have to understand that immersion switching is most popular with users who have free PV systems installed, where someone else is collecting the FITs payments. Using Immersion switching for them is a way of getting the maximum benefit from the system they have installed on their roof, and they do not have any issues wrestling with green issues or their conscious, of whether or not they are exceeding the 50% export allowance.


regards Keith











Edited default (Oct. 27, 2013 17:25:00)

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#5 Nov. 5, 2013 14:57:00

rogerhoward
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The Intelligent Immersion


Wow. Absolutely stunning stuff, Keith.


I've brought this to the attention of a local Solar PV friend of mine. He'd said that he was interested in ways to better utilise his Thermal Store. Maybe now he'll finally join Microgen - God knows I've been trying to persuade him.


Surely, Keith, a posting of these investigations of yours onto forums like Navitron, the Electricians Forum, GreenLiving forum, etc. would be hugely welcomed - this is real “scientific investigation” :-)










Economy 10 tariff provides 6.9p/kWh off-peak import between 12am-5am, 1pm-4pm and 8pm-10pm; http://www.pvoutput.org/aggregate.jsp?id=21047&sid=18934&v=2&t=m on approx. 63% off-peak usage, 22% solar usage, and 15% peak-rate usage.
1,900kWh annually is exported, mostly in summer, on approx. 3,200kWh generation. Approx. 4,500kWh/year is imported, mostly for (a) winter and springtime off-peak Storage Heaters, and (b) off-peak hot water Immersion heating (which is “dumb”, i.e. not linked to the solar PV).
PV array is split East-West. Income is from Phase II 21p/kWh Feed-in-Tariff plus smart metered 3.2p/kWh Export Tariff.

Edited rogerhoward (Nov. 5, 2013 14:57:00)

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#6 Nov. 13, 2013 12:27:00

SteveRogers
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The Intelligent Immersion


Not sure Navitron would welcome promotion of the Intelligent Immersion.  The parent company behind the site promotes/sells Immersun I think!  I believe that Edward Chase has tried to discuss it on their site and was bombed off for “spamming” (i.e. promoting his own product)!


Steve





Edited SteveRogers (Nov. 13, 2013 12:27:00)

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#7 Nov. 13, 2013 14:21:00

bhommels
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The Intelligent Immersion


Hi Keith,


Excellent summary, thanks. The good folks at openenergy.com have found that (digital) consumption meters increment their internal counters in 1Wh steps. Consequently, chunks of energy smaller than 1Wh can be pushed/pulled from the grid without the meter incrementing. (This explains why burst fire immersion controllers work without the meter ticking up in the first place)


A 3kW immersion heater consumes 3000Wh in 3600s, or 1Wh per 1.2 seconds. If the immersion controller reacts to power variations within this time window, consumption is avoided. In practice, transitions from full-on to full-off rarely occur, and a somewhat longer reaction time will be fine.


The openenergy monitor implementation measures 40+ samples per mains cycle, and decides after each cycle whether to switch the next cycle on or off. IMHO this implementation is hard to beat in reaction time or efficiency.


Regards, Bart





Edited bhommels (Nov. 13, 2013 14:21:00)

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#8 Nov. 14, 2013 19:49:00

SteveRogers
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The Intelligent Immersion


Just a head's up to say that Intelligent Immersion have done a deal with Eco-eye to sell their Smart PV meter for £69 (inc VAT i.e. a saving of £15) if bought with at the same time as the I2 switch.  So you get both for £317.40 (inc VAT).


You have to buy both from Intelligent Immersion (http://www.intelligent-immersion.co.uk/).


Steve





Edited SteveRogers (Nov. 14, 2013 19:49:00)

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#9 Nov. 15, 2013 16:09:00

phsci
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The Intelligent Immersion


I have a 3.8 kWp PV system which produces just over 3000kWh per year and I had an Intelligent Immersion device fitted on 4 October (I know, just as the main production period finished for this year, but at least it will be in place for the whole of 2014).  At the same time, I had my electrician install a couple of Landis Gyr 5235 meters: one to measure cumulative export to the grid and the other to measure energy diverted to my 3kW immersion heater.  Now I know exactly how much I am exporting, and also by adding the second meter reading how much I would have exported without the Intelligent Immersion. 


Early days yet of course, but from 7 October until 11 November my PV production was just 167 kWh.  Of this, 66 kWh was diverted to the immersion and 2.9 sent to the grid. So I now know that without the Intelligent Immersion I would have exported 41% during that period but with it just 1.74%. (I am at home for much of the week and try to consume as much of my production as possible by using discretionary appliances during the middle part of the day and opting to do this on the best-looking production days.)  I realise that during the summer my figures will look rather different, but so far my experience is positive.  The installation was straightforward, and I am impressed with the speed of reaction of the Intelligent Immersion which does its stuff instantly in response to changing import/export conditions.


If I can do without my boiler being fired up for hot water during next year’s brighter months then I believe I shall be able to make some worthwhile savings.  I was shocked to discover that according to the SEDBUK boiler efficiency database, my wall-mounted, modulating, condensing boiler has an overall SAP 2009 annual efficiency of 89.4%, but the rating for ‘comparative hot water efficiency’ is only 58.2%.  It seems therefore that each kWh of electricity will be equivalent to 1.72 kWh of gas, and that’s before heat losses in transmission between the boiler and the hot water storage cylinder.





Edited phsci (Nov. 15, 2013 16:09:00)

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#10 Nov. 15, 2013 16:48:00

SteveRogers
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The Intelligent Immersion


Bart,


Not sure I understand this thing about digital consumption meters.  By this do you mean the distribution company's meter (on which our bills are based, though not the older, analogue wheel type) or something else (like the open energy monitor)?


I guess this means that 1Wh increments can be used without paying for them?  (I hope the PV production meter isn't prone to this too!  Only joking! )


I guess you are saying that the reaction time of the immersion switch is important to avoid import when the solar power takes a sudden drop?


Steve





Edited SteveRogers (Nov. 15, 2013 16:48:00)

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