#1 Dec. 1, 2013 12:14:00

SteveRogers
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Solar iBoost immersion switch


Does anyone have experience of this device?


http://www.biggreentechnology.com/marlec-solar-iboost-free-hot-water-from-solar-pv.html#Reviews


It seems to be different from many others in that there is a wireless sender which conveys a signal to a remote switch (which could be then next to your immersion tank in the airing cupboard - as long as you don't smother it with clothes and towels that are airing ).  This might make installation a little easier, though the bumpf states that a qualified electrician should install it.


The other advantage it has over e.g. the Intelligent Immersion is that it stores information about energy saved (i.e. diverted to heating water).


I can't make out if it is fully proportional - they seem to duck a straight answer to that question in their FAQs .


Steve





Edited SteveRogers (Dec. 1, 2013 12:14:00)

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#2 Dec. 2, 2013 09:01:00

daved42
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Solar iBoost immersion switch


how do you mean proportional


  daved42





Edited daved42 (Dec. 2, 2013 09:01:00)

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#3 Dec. 2, 2013 13:59:00

SteveRogers
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Solar iBoost immersion switch


I believe that this means that the instantaneous amount of electricity diverted to the immersion heater is proportional to the instantaneous power being produced by the PV system (subject to a small latency, I guess).  Bart Hommels will be be able to give you chapter and verse on this .  He has built his own immersion diverter (based on http://openenergymonitor.org/emon/node/2429 I think).





Many of the older immersion switches were a simple, mechanical relay that switched on when the PV power generated exceeded a minimum value.





The proportional type is much more efficient as this minimum can be very small so one can make use of excess production even under poor conditions.  I guess it can also “switch” on/off much faster than a mechanical relay too.





Now, to quote two of the iBoost's FAQs:


Is the Solar iBoost a “proportional controller” or a switch? - Solar iBoost cleverly only allows the excess power generated to be diverted to the immersion, as this varies the Solar iBoost manages that power into the immersion to any Watt value up to 3kW. It is not an open and close switch.


When does my Solar iBoost start putting energy into my hot water tank? - As your PV array starts to generate in excess of your household power requirement the Solar iBoost will begin to “dump” energy into your hot water tank. For example if you have 2.2kW of export energy then the Solar iBoost will dump 2kW into the immersion to heat your tank of water. There is a buffer of 200W to ensure that the Solar iBoost deals smoothly with the changing use of household energy and the PV array's generation thus avoiding any draw from the grid.


I am not clear why the answer to the first question was not an unequivical “yes” .  I don't know what the threshold minimum power is for other immersion diverters and whether 200W is high.


I had decided to buy the Intelligent Immersion but the data logging on this iBoost is quite attractive and the price is competitive.



Steve









Edited SteveRogers (Dec. 2, 2013 13:59:00)

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#4 Dec. 2, 2013 16:48:00

SteveRogers
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Solar iBoost immersion switch


Also, have a look at Keith's posting here - http://www.microgen-database.org.uk/forums/general-discussion/the-intelligent-immersion#idiO6iMhYfOjOu1Zs99bcpsg





Edited SteveRogers (Dec. 2, 2013 16:48:00)

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#5 Dec. 6, 2013 13:41:00

SteeveeLeevee
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Solar iBoost immersion switch


Hi Steve,


I have a Solic immersion switch, it diverts any output that would be exported to your immersion heater (until the water is hot enough by thermostat) and then exports when the water is hot enough.


Have not used gas for hot water from installation end of June until 1st week Nov.





Steve





Edited SteeveeLeevee (Dec. 6, 2013 13:41:00)

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#6 March 6, 2014 16:32:00

SteveRogers
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Solar iBoost immersion switch


Well, I bought a Solar iBoost from ebay for £255 and paid my electrician £30 to fit it which seemed easy.


Not clear if it's working yet as I forgot to re-program the central heating hot water cycle so it's had a full hot tank to start the first two mornings and today it's been really overcast (max power around 500W) and it hasn't turned on so there's been little to export 


I'll update when I know more about how well it's working.


Steve


URN 215 North Yorkshire 3.96 kWp, S facing, 40 deg tilt, minor shading





Edited SteveRogers (March 6, 2014 16:32:00)

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#7 March 18, 2014 09:35:00

SunnySouthwell
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Solar iBoost immersion switch


Any idea how your iBoost is doing yet ?


I like the look of this device and the ease of installation, and I guess that I'm just looking for some justification to my wife for spending £250 or so.


Steve Webb


URN 6390, Southwell,








Edited SunnySouthwell (March 18, 2014 09:35:00)

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#8 March 23, 2014 17:54:00

SteveRogers
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Solar iBoost immersion switch


The iBoost is working OK but I need to turn off the oil water heating to give it a proper test.  Being cautious at the moment, I am topping up with 1/2 hour of oil-fired heating in the evening (usual wet central heating system/coil in hot water tank).  This means the tank is starting warm-to-hot in the mornings.  On a typical sunny day it is diverting around 2.5 to 3 kWh to the immersion tank (and the water is very hot, at least at the top).  Being only two of us in the household we don't use a lot of hot water, though 3 kWh does sound low.  It's works out about 10-30% of the daily production (which is averaging 12 kWh since iBoost installation).


I've changed my showering habit to use water from the tank rather than the instant demand shower, so import should drop a bit.


I'll give it another few weeks before I draw final conclusions but here's some thoughts:


(i) The iBoost was cheaper and easier to install than the i2 would have been.  I paid £255 (eBay) + £30 for installation which took my electrician 1/2 hour.


(ii) The iBoost's 200W threshold means that not much is diverted on dull days and the i2 (30W threshold) would have an advantage here.


(iii) I like the amount of data that is available on the iBoost readout (instantaneous power, kWh diverted today, yesterday, last 7 days and last 28 days) whereas the i2 only give instantaneous power I think and you'd need a separate meter to monitor kWh diverted.


(iv) The update rate is 8-10 seconds, so I guess a little import might occur when a kettle is turned on for example.  The power diverted lags a bit behind the actual excess power generated by the panels and the buildup is smoothed between the updates.  The manufacturer says this, and the 200W threshold, are aimed at eliminating import and I guess avoids flickering lights, etc.  I'll investigate this smoothing further to see if I can make sense of it.


(vi) I could think about optimising the amount of the tank heated e.g. by installing a pumping system, a second immersion heater or, easiest and cheapest, a longer element (36“ vs the present 27”).  I'll see if we run out of hot water first


(v) Calculating pay back time will be complicated as I need to take into account diverted production, reduction in oil usage, reduced import (shower habit change), etc.  I think I'll need a year's use to get this right.   However, if we can save 18% on our oil usage it will pay for itself in a year and that doesn't sound an unreasonable expectation to me.  That will also be pretty “green” I think


Hope that helps for now,


Steve


URN 215 North Yorkshire 3.96 kWp, S facing, 40 deg tilt, minor shading








Edited SteveRogers (March 23, 2014 17:54:00)

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#9 March 24, 2014 00:03:00

daved42
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Solar iBoost immersion switch


I have had an I-boost since october, and changed my immersion from a24“ to a 30” the trouble is the stats are the same length 18“ so I'm going to fit a circulater pump to give a full tank. I'm hoping this will over rule my gas stat @ 24” down the cylinder, and stop the boiler from cutting in. The I-boost seems quiet good except for loosing communication once or twice due to a duff battery, and transmitter position.   I hope this helps 





Edited daved42 (March 24, 2014 00:03:00)

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#10 March 24, 2014 08:45:00

SunnySouthwell
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Solar iBoost immersion switch


Thanks for the update Steve.  I bit the bullet at the weekend and ordered one (like you, from ebay, £255), and all being well will have it installed by the end of the month.


My plan was to do as you do, reset my gas water heating time to only work for a short period early evening to top up if neccesary, my wife and I usually have baths before bedtime and use hot water then, daytime use is fairly small.  I'm hoping that there'll be enough hot water in the morning to do the washing up.  If not, we'll boil a kettle.


I don't know what my immersion thermostat is set to, but I'll probably turn it up, and I'll leave the gas water heater thermostat as it is.


I think that the ease of installation was the big selling point, and the price of course.


Steve Webb


URN 6390, Southwell





Edited SunnySouthwell (March 24, 2014 08:45:00)

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