Do immersun type devices work

[robertevans68]

Hi, I'm new on here and am having a 4kw pv system installed this week.
I obviously want to get the most from my purchase and have been searching for ideas, one of the best things i can see is the immersun. Is there any other similar devices I should look at or do these type of devices work?

Thanks Rob

 

[Gavin A]

Immersun work well, I can't speak for any of the other products, but we checked them all out a few weeks ago before determining that Immersun seemed to be the best on the market at a reasonable price.

 

[sedgy34]

Will segen or Krannich sell these units a recent customer may benefit from one

 

[FB.]

Immersun work well, I can't speak for any of the other products, but we checked them all out a few weeks ago before determining that Immersun seemed to be the best on the market at a reasonable price.

And the cost if the unit is.........?

I also note in the manual that it says:
"......Do not attempt to wire this unit if you are not a qualified or an experienced electrician....."

And how much more would that add to the cost, if people have to get an electrician to fit it?

 

[sedgy34]

And the cost if the unit is.........?

I also note in the manual that it says:
"......Do not attempt to wire this unit if you are not a qualified or an experienced electrician....."

And how much more would that add to the cost, if people have to get an electrician to fit it?

Speak to your installer if they are still around

 

[FB.]

Speak to your installer if they are still around

Can give just a vague indication on what a customer should expect for pricing?
Lack of information just encourages people to do nothing and lose interest, which is what I'm now inclined to do, as I expect the secrecy on pricing means that it can be very expensive.

 

[BruceB]

google 'immersun price' and there are at least a couple of hits with prices, including a contributor here.

 

[Gavin A]

indeed... Immersun installed price from £499

which I think is relatively standard for a straightforward installation.

 

[sedgy34]

Can give just a vague indication on what a customer should expect for pricing?
Lack of information just encourages people to do nothing and lose interest, which is what I'm now inclined to do, as I expect the secrecy on pricing means that it can be very expensive.

I would imagine you are looking to pay the cost of the immersun unit and around £80/100 for a sparky to wire it in.

 

[MicraShed]

indeed... Immersun installed price from £499

which I think is relatively standard for a straightforward installation.

Thats what I have been quoted plus a bit extra because Im outside the usual coverage area for te installer. I need to sort out a date for an install with them actually but Ive been in and out of damn hospital again this week.

Given the cost of the unit is roundabout the £380 - £400 mark from the company that makes them from what I did find out (Google be your friend here).
Add in materials (cable etc), travelling, VAT and other sundries then another £99 on top isnt really that bad for a qualified spark to fit it. Whilst it might sound a fair wedge for a box of bits, having researched the unit (all-right so far it does seem to be anecdotal evidence) they do two things - the make sure almost every scrap of electric you generate is used, and they reduce the energy (gas or electric) you use to heat your water.
Now for me, given that my domestic gas use is pretty much entirely water heating use between about March time and October time and given that Im using about 14kW/day between these months of gas.

So, gas at about 4.1p/kWh x 14kWh x 210 days (appx) = £120.40

Potentially in the months where I dont have the heating on for anything other than hot water that is a saving of £120. There should be additional savings through the year as well, so the "payback" time for me at least will be about 3 to 4 years, possibly less.

These are only rough calculations of course, but it certainly seems a viable proposition. My only concern is whether or not there are any "moving" parts (eg, power relay) that might have a limited lifespan and need maintaining during the payback period.

Of course I could be talking out of my bum here, so I welcome other peoples thoughts or experiences.

 

[robertevans68]

Thanks for the replies. I've been quoted £359 for the unit

Rob

 

[Worcester]

3 to 4 years is about right, if you are on oil it'll be less.

Plus you can add in an addtional device, we have yet another installation going in next week doing just that, Immersun + 3 x Dimplex DXLWP800. Other heating is an oil fired rayburn, so once the immersion is up to temp, the goal is then to send the output to these just to take the chill off one of the bedrooms and extended hallway, as that part of the bungalow acts as a 'heat sink'. Base price as above plus e/o for the heaters, trunking, cabling isolators and time, though being a bungalow with good loft access, the extra time shouldn't be more than an hour, and customer is happy with / suggested surface mount trunking. - oh and yet again this is an installtion that we didn't do, they approached their original installer first who wasn't interested!

If you want a local installer go to Where to Buy :: immerSUN :: Use 100% generated free electricity :: A 4eco Product look closely and you find a lot of senior forum members listed as installers!

 

[FB.]

Immersun + 3 x Dimplex DXLWP800.......the goal is then to send the output to these just to take the chill off one of the bedrooms and extended hallway!

Yes, you've no doubt seen my topic relating to my central heating, and in the cooler weather earlier this year, we have been using a couple of 500W electric conservatory heaters to boost the lounge temperature when the 3.75kWp solar is producing well.
With the gas and electric tariff's we're on, and the 75% efficiency of my boiler v 100% efficiency of an electric heater, the cost of electric works out about is about 1.7x that of gas.
So as long as the solar can contibute about 250W, a 500W heater is no more expensive to run than the central heating; and probably cheaper if it's just a degree or two extra heat required in one or two rooms. Not to mention the 95W central heating pump's power consumption, the boiler's power consumption and losses through the pipes in the walls and between the floors.

In fact, my earlier interest in Immersun was the possibility of adding an additional socket in the lounge (we would really benefit from one more socket and the CU is on the other side of the lounge wall), and have that socket as a surplus solar electricity dumping point.

 

[MicraShed]

In fact, my earlier interest in Immersun was the possibility of adding an additional socket in the lounge (we would really benefit from one more socket), and have that socket as a solar electricity dumping point.

Wouldnt the load have to be resistive though and not inductive? How could you be sure that whatever was plugged in would be a resistive load - also, would the Immersun dump to the socket if there was no load detected? I dont think it would.

 

[FB.]

Wouldnt the load have to be resistive though and not inductive? How could you be sure that whatever was plugged in would be a resistive load - also, would the Immersun dump to the socket if there was no load detected? I dont think it would.

Yes, it would have to be certain types of load on the socket (and labelled appropriately), and if nothing was connected the power would be lost to the grid.
Perhaps split between a 1-2kW immersion element and a dump-socket in the lounge.
I've seen lower-powered immersion elements here (but have not dealt with them, nor do I know anyone else who has, so I can't vouch for the company):
Immersion Heaters from Surejust

 

[robertevans68]

Hi,
So basicly I could use an immersun to run a 1kw immersion and a couple of heaters in bedrooms, if total load is less than 3kw?

Thanks Rob

 

[Worcester]

Yes, or use your exisiting 3 kw Immersion and when that is up to temperature let it roll over on to the heaters, or if you have a very large system PV and low base load, you can link two immersuns together to control up to 6kW proportionally.

If you link up 1kW immersion and 2 x 800W heaters on the same circuit, at the same time as you suggest, when the 'spare' output from the PV system is 1.3 kW then 500W will go to the immersion and 400W to each of the heaters. so the water will take loner to heat up, and you may just get everything luke warm.
Also if you wire a 1 kW immersion in 'roll over' mode, will take a lot longer to heat if you have spare PV generation > 1kW as the immersion won't take more that 1 kW.

 

[liquidity]

Thats what I have been quoted plus a bit extra because Im outside the usual coverage area for te installer. I need to sort out a date for an install with them actually but Ive been in and out of damn hospital again this week.

Given the cost of the unit is roundabout the £380 - £400 mark from the company that makes them from what I did find out (Google be your friend here).
Add in materials (cable etc), travelling, VAT and other sundries then another £99 on top isnt really that bad for a qualified spark to fit it. Whilst it might sound a fair wedge for a box of bits, having researched the unit (all-right so far it does seem to be anecdotal evidence) they do two things - the make sure almost every scrap of electric you generate is used, and they reduce the energy (gas or electric) you use to heat your water.
Now for me, given that my domestic gas use is pretty much entirely water heating use between about March time and October time and given that Im using about 14kW/day between these months of gas.

So, gas at about 4.1p/kWh x 14kWh x 210 days (appx) = £120.40

Potentially in the months where I dont have the heating on for anything other than hot water that is a saving of £120. There should be additional savings through the year as well, so the "payback" time for me at least will be about 3 to 4 years, possibly less.

These are only rough calculations of course, but it certainly seems a viable proposition. My only concern is whether or not there are any "moving" parts (eg, power relay) that might have a limited lifespan and need maintaining during the payback period.

Of course I could be talking out of my bum here, so I welcome other peoples thoughts or experiences.

The only flaw I can see in your calculations is perhaps not factoring in what time of the day the gas use takes place. Although I have never looked at the meter on a typical day I suspect most of my gas use takes place in the morning, first as the hot water is brought back up to temperature after cooling overnight, then after the first shower and then once more after the 2nd shower. These showers typically take place before 09:00 5 days a week when most PV systems will only have produced a few kWh. And even if a 4 kWp system is running at 100% at 08:00 it still isn't pouring as much heat into the hot water tank as your boiler will so the reheat time will be longer.

The surplus kWh from PV will help cover the cost of any hot water use during the day and early evening though.

Thus I think the payback time for something like the Immersun will be considerably greater for my hot water use profile which is probably not far different than many people's.

 

[Gavin A]

insulate your tank properly though and the water should remain hot overnight from the previous days heating.

 

[FB.]

insulate your tank properly though and the water should remain hot overnight from the previous days heating.

Our hot water tank (3kW element, about average tank size) was without a jacket for a while earlier this year.

From almost cold, without the jacket (a basic red B&Q/Homebase-type), the heating time was about 75 minutes. With the jacket it was about 45 minutes.

If the hot water was unused, the amount of time before it began reheating went from about 75 minutes without the jacket, to about 120 minutes with the jacket.

In other words: by having a boiler jacket, the heating time was almost halved, and the time before reheating was almost halved. Half as much power usage to heat it, and half as much power usage to maintain it at a hot temperature.

So for those who don't have one; £10-15 for a boiler jacket should pay for itself after just several weeks.

 

[robertevans68]

Our tank is already insulated with foam jacket from the factory, but the tank cupboard was always really warm. Last week I fitted an additional red jacket from BQ and now the cupboard is cool so this must be a good thing.

 

[liquidity]

When you say without a jacket do you mean just a bare copper cylinder? My post above is referring to a 20 year old copper cylinder with perhaps 1.5 inches of hard foam insulation bonded to the cylinder at the time of manufacture.

 

[FB.]

Our tank is already insulated with foam jacket from the factory, but the tank cupboard was always really warm. Last week I fitted an additional red jacket from BQ and now the cupboard is cool so this must be a good thing.

The tank I mentioned earlier had a tough foam-like, pale greenish coating on it, maybe 2cm thick. It wasn't bare copper.

Adding the jacket to the hard-foam-coating roughly halved the power consumption or roughly doubled the time between reheating.
Had it been bare copper I expect it would be doubled again.

 

[Digon]

I've been using a home made proportional controller, similar to the Imersun, with my 4kWp system since April and can say they are definately worthwhile.
How much you can get out can vary a lot depending on how you set things up.
My system was a standard 120L tank with 27" immersion and because I have a toddler in the house I had to limit the thermostat to 60 DegC, which was probably still too high. For the last 3 1/2 months this setup has been shutting down at about 11 am on good days and 1pm on cloudy days. This was adequate without supplimentary heat for 2 x evening baths plus general kitchen use or 1 x evening bath and 1x morning shower. I've logged the (true) energy sent to the immersion and it's been pretty consistent at 185 kWh/ month from about 350 - 430 kWh/ month generated.
Two weeks ago I modified my system and it's made a big difference so far with 7 -11 kWh/ day now going to the immersion, conditions permitting of course.
The mods I made where to fit a larger 150L tank (second hand off Ebay), 36" immersion which reaches to within a few inches of the concave tank bottom and a thermostatic temperature control on the tank outlet so I can run the tank hotter without scald risks at the taps.
I also switched the washing machine and dishwasher to hot fill and carefully time there use. Currently the washing machine goes on about 9- 10 am as it will drain whats left of the previous days heated water before the rinse cycles.
The dishwasher which doesn't use anywhere near as much water goes on about 1- 2 pm and uses enough water to re-engage the immersion thermostat to use some more of the afternoon sun.
The thermostat will still cut out by about 5pm on good days but the only way I could store any more energy in my current setup would be to use a pump for tank stirring which would not be easy plumb in to my system.
I may put a second hand storage heater on a relay linked to the thermostat but I don't think there will be enough spare energy during the winter months when it will be needed.

 

[liquidity]

Digon - thanks for sharing your actual results to date. Can you post a link to any design info on the controller?

 

[Digon]

It is a design by a member of this forum, Pmcalli. There was a long thread on here discussing the design of these devices but I can't find it right now. as I'm not on aPC.

 

[MicraShed]

The only flaw I can see in your calculations is perhaps not factoring in what time of the day the gas use takes place.

Both my heating and hot water are controlled by a thermostat only. No time clocks.
So when the room stat calls for heat the boiler fires up and delivers heat (with surplus heat being dumped into the cylinder via the gravity hot water set up) TRV's shut off when individual rooms get up to temp.

If however the cylinder calls for heat, then the boiler fires up and delivers the heat via the gravity feed set up to the cylinder.
The downside of the gravity set up is that there is a very long run on the pipes so heat is wasted there, and the boiler ends up cycling as the heat does not disappate fast enough into the cylinder.

The cylinder is 17 years old and insulated by both a foam jacket and red jacket.
Pipes are insulated as well as they can be by foam.

 

[nicksgonesurfin]

4 KW of PV produces 4 x 900 units in the south west 850 in norfolk 800 in scotland. 3600

ten units a day at best during the winter its going to be more like 3-4 units which is when you use any hot water for heating.
This device will certainly cover hot water usage in the summer but i dont think it will achieve as much. Ideally you need a heat store Large well insulated thermal store to keep the heat in. You also need a range of immersion heaters as most are at least 2KW most are 3 KW. So if your exporting 1 KW and your 3 KW immersion kicks in then your using two units of electricty at 14p per unit =28p rather than Gas ' 4.2 p per unit x 2 = 8.4p that means it could cost you 60p a day extra

 

[Worcester]

You also need a range of immersion heaters as most are at least 2KW most are 3 KW. So if your exporting 1 KW and your 3 KW immersion kicks in then your using two units of electricty at 14p per unit =28p rather than Gas ' 4.2 p per unit x 2 = 8.4p that means it could cost you 60p a day extra

@niskgonesurfin, That's the whole purpose of inmmersun type devices, the PROPORTIONALLY control the power to the immersun so YOU DON'T import, and if you've only got 751 watts available that's all it will send to the 3kW immersion:

This ImmerSun was installed on the 22nd December 2012:

 

[danesol]

4 KW of PV produces 4 x 900 units in the south west 850 in norfolk 800 in scotland. 3600

ten units a day at best during the winter its going to be more like 3-4 units which is when you use any hot water for heating.
This device will certainly cover hot water usage in the summer but i dont think it will achieve as much. Ideally you need a heat store Large well insulated thermal store to keep the heat in. You also need a range of immersion heaters as most are at least 2KW most are 3 KW. So if your exporting 1 KW and your 3 KW immersion kicks in then your using two units of electricty at 14p per unit =28p rather than Gas ' 4.2 p per unit x 2 = 8.4p that means it could cost you 60p a day extra

Given that is you heat your hot water cylinder with electric, I thought most ppl used GCH like me ??

If you do use GCH - the benefit could be less but still rewarding, again its all about knowing your systems, your needs and whats possible with your system, especially figs like whats your export rate to grid to work out ultimately your ROI !

 

[Worcester]

I thought most ppl used GCH like me ??

Not round here! - the majority are on liquid gold aka oil, and turn their boilers off from May - October.

like whats your export rate to grid to work out

Irrelevant when deemed.

 

[danesol]

Not round here! - the majority are on liquid gold aka oil, and turn their boilers off from May - October.

Yes I would agree it would make total sense if had no GAS and were using electric, Oil etc

Irrelevant when deemed.

How can it be irrelevant if you use every last kwh from your Solar array ( ie. use more or less every thing you generate ) - these types of device simply wont return anything then as they wont switch on so I dont understand your comment - explain ??


I'm just doing the calculations now for our household and although we export only 33% of our total generation and use GCH for the primary source to heat the water - there is still some advantage in using one of these types of device but for us it will be along term investment ( looking atm at 8yrs at the cheaper SolarImmersion and far longer for the more expensive Immersun )

However still worth looking at as an add-on and should you get this as a Solar PV package/bundle at the right price your laughing... as i state before every little bit helps

 

[nicksgonesurfin]

Given that is you heat your hot water cylinder with electric, I thought most ppl used GCH like me ??

If you do use GCH - the benefit could be less but still rewarding, again its all about knowing your systems, your needs and whats possible with your system, especially figs



Domestic export is always based on 50export unless you have an import export meter.
Most people do not.

Then your getting paid export plus any savings you make from using more than 50%

@Worcester renewables.

Thanks I didn't know it was a proportional system .

So it will dump what ever is spare into your system?

Good too know.





like whats your export rate to grid to
work out ultimately your ROI !

Thanks for the help see answer in quote above

 

[danesol]

Thanks for the help see answer in quote above

Just not sure what you were trying to tell me then but so we are clear......

Your FITs provider currently give you 50% export payment ( based on your readings ) regardless of what you ACTUALLY provide.

However in reality you could be sending 80% of your total generation to the grid which although you are getting paid for its initial generation, you are ultimately wasting free energy you could utilise...... hence the inclusion of this device to "play the system".

If HOWEVER like me you use the vast majority of your generated electric - there is very little left to use elsewhere and this is what I am suggesting.... the more sauvy PV owner would know this by either monitoring devices or by use of PVO for example

hth

 

[Worcester]

Your PV system is giving you a return over 8 - 10 years which you thought was a good investment - so why isn't an ImmerSun type device when it gives the same return?

- - - Updated - - -

If HOWEVER like me you use the vast majority of your generated electric - there is very little left to use elsewhere and this is what I am suggesting.... the more sauvy PV owner would know this by either monitoring devices or by use of PVO for example

Correct, I agree.

 

[Worcester]

Try using the eco-eye Eco-Eye | Real Time Electricity Monitors | UK - it has an RF device and you can link it up through your pc via cosm (ex pachube) to pvoutput.org (Eco-Eye | Real Time Electricity Monitors | Eco-Eye with Microgeneration/Photovoltaic Installations Eco-Eye | Real Time Electricity Monitors | Eco-Eye used with your computer)

This one uses that system above and has an ImmerSun installed - you can wee how it tracks plus when they had breakfast and put the kettle on

 

[danesol]

Your PV system is giving you a return over 8 - 10 years which you thought was a good investment - so why isn't an ImmerSun type device when it gives the same return?

- - - Updated - - -



Correct, I agree.

No I agree, as long as it lasts that long.... however I was merely pointing out that some will gain enormously with one of these devices ( typically PV owner who uses no electric during the day when sun is out ) but others may not gain so much at all ie. me for example and the risk of achieving the return is higher.

 

[Warlord2001c]

Try using the eco-eye Eco-Eye | Real Time Electricity Monitors | UK - it has an RF device and you can link it up through your pc via cosm (ex pachube) to pvoutput.org (Eco-Eye | Real Time Electricity Monitors | Eco-Eye with Microgeneration/Photovoltaic Installations Eco-Eye | Real Time Electricity Monitors | Eco-Eye used with your computer)

This one uses that system above and has an ImmerSun installed - you can wee how it tracks plus when they had breakfast and put the kettle on

View attachment 17982

I recognise my graph when I see it! Worcester fitted my Immersun less than two weeks ago and it has so far pumped over 30kWh into my hot water tank... Not bad at all considering we've seen very little sun since that day. Most days we have returned from work to a tank of hot water and the boiler has spent almost no time on water heating since then. The tank has very good insulation and we've been able to draw a nightly bath for the young man plus morning showers before the Immersun started again for the following day.

The eco eye smartPV is also proving very accurate as I've been verifying these PVoutput figures against the inverter log and SD card storage from the device which is four second samples rather than 5 minute averages that are sent to COSM.

very happy with both Immersun and smartPV. The PV suppliers were pretty good too!

 

[Berneray]

We have installed about 15 immersun units...though most of them since December so its hard to tell how well they are working yet.

We charge £450 to supply and install if its done at the same time as the PV system. £500 if its a retrospective fit.

One small point we have found....None of the monitoring devices work with Immersun.

Wattson do a similar system Optimersion that works with their monitoring system....but we are sticking with the Immerson....(When we can get stock that is)...

 

[Warlord2001c]

One small point we have found....None of the monitoring devices work with Immersun

Do you mean they don't work at all or that they give false readings?
I use the Eco Eye unit and yes it does add the immersun draw to the grid total when running so gives an overstated grid consumption figure.
To be honest though I'm seeing that as a positive for me as when shown on PVOutput I'm getting a very clear indication of where the immersun is working to bring the PV and Grid totals in sync so I see how little of my PV generated power is going to the grid.
The figures for PV Generation are unaffected and accurate and the Grid total is monitored by my Electricity supplier anyway so not a biggy for me.

 

[adamgp]

Plenty of cheap offers on Google to take advantage of regardless of whether you're a trade customer or not.
Shouldn't take more than an hour to wire from the distribution board to an immersion heater. It only needs about 135 watts of excess power before switching I believe and trickling all excess to the heater!

 

[nicksgonesurfin]

I think this brings an interesting challenge to behavior, 100yrs ago we would have bathed (if we actually did bathe) With the fire heated water, possibly after cooking and eating using the fire. mainly in the evening. Going to bed clean.

Perhaps we have to bathe in the evening?!

another idea is to insulate your tank further or design so the losses over night are minimised and all the PV powered heat is maximised and ensure when the last person has had a shower the HW is turned off so no heating except the solar can go into your system.

seems a lot of hassle i know but its a little like stoking the fire to a roaring flame then going off to work. we wouldnt do that. Because we are disconnected from our energy we don't think about our boilers working when we are not there. (some people do, Timers etc!)

 

[adamgp]

Absolutely, and set your gas boiler to kick in the evening after the sun has set or is setting to make up the difference.. at least this is what I do to maximise the PV energy usage.

 

[bommels]

For more than a year I have been running an early DIY immersion controller, with energy logging capability. Attached is a bar graph of the generation in kWh for April 2013 (2.88kWp array).
The logging allows tracking of where the energy goes: yellow indicates export to grid, red means it has been diverted to the immersion heater, and green marks the PV energy that has been used elsewhere in the household. The system has proven to be so effective that we rely on it entirely for domestic hot water in summer. And, as you can see from the plots, there is still room for improvement, as 42% of our solar PV production was pumped into the grid.

Do immersion controllers work? Certainly they do!

 

[BruceB]

Coincidentally, I had an email today from one of my customers I worked with in the early months of this year putting right a solar pv, solar thermal and ashp installation put in by others. He is full of praise for the immersun. He has about 5kW of PV and a 300 litre Gledhill thermal store in the loft.

"...The Immersun unit has diverted 428 Kwh thus far and is the biggest positive of the project. The only slightly off-putting thing is the noise of a monstrous kettle going off above your head in the bedroom. On a sunny day there are 3Kwh going into the immersion, and you do know it. It becomes the sound of money being saved, and you come to love it........."

 

[BruceB]

I also installed a bank of three thermometers showing the top, middle and bottom temperatures of the thermal store. £10 each from Maplins mounted in his sitting room. Just extended the sensor cables with cat5e. Cheap, cherful and effective. 3-in-1 Digital Probe Clock Thermometer : Thermometers & Hygrometers : Maplin Electronics

".......The three temp gauges in the tv room are the most cost effective part of the deal; we now know exactly what we are dealing with and how effective the wood burner is at a quick burst of heat in the evening; superb."

 

[danesol]

For more than a year I have been running an early DIY immersion controller, with energy logging capability. Attached is a bar graph of the generation in kWh for April 2013 (2.88kWp array).
The logging allows tracking of where the energy goes: yellow indicates export to grid, red means it has been diverted to the immersion heater, and green marks the PV energy that has been used elsewhere in the household. The system has proven to be so effective that we rely on it entirely for domestic hot water in summer. And, as you can see from the plots, there is still room for improvement, as 42% of our solar PV production was pumped into the grid.

Do immersion controllers work? Certainly they do!

View attachment 19012

How many CT sensors have you got fitted to get that level of info and what make are they - do you have a central monitor too ??

 

[bommels]

Hi Danesol,
My setup uses 2 clamps. One clamp sits around the tail at the consumption meter, measuring net import/export, the other clamp sits around the tails leading to the PV system.
Earlier, I have verified that the actual power going into the immersion heater corresponds to what the system thinks is going in there, so I do not have to use a clamp for that.

The clamps were recuperated from the scrap heap and have custom resistors fitted to limit the amplitude/range. Presumably the usual clamps would work just as well. I have not been chasing sub-1% accuracy I must admit.

 

[apj]

I'm considering PV, with flat roof garage could get 6kw system.
heating system is oil, so in addition to immersion i was considering some additional wall mounted rads with heating element direct from PV, can the immersun divert to more than one outlet or would multiple units be needed?
BruceB, graph is a very good idea, a couple of very low generation days - were these much more frequent over winter??

 

[danesol]

I'm considering PV, with flat roof garage could get 6kw system.
heating system is oil, so in addition to immersion i was considering some additional wall mounted rads with heating element direct from PV, can the immersun divert to more than one outlet or would multiple units be needed?
BruceB, graph is a very good idea, a couple of very low generation days - were these much more frequent over winter??

Would it even be worth it going over the domestic threshold of 4KW, considering for a moment rates change commencing Aug 2013 and the reduction in tariff going over 4kw ??

The immersion question is possibly secondary to this ?

All I would say is do the numbers very carefully - I assume you will stay in the building for the next 20yrs too !!!