PV immersion heater proportional control

[thushar]

I don't have hot water cylinder but have a boilermate 2000, I am buying a new car this year and was looking at Vauxhall Ampera hybrid car could charge it when not used with is device?

Mark II switch from Intelligent Solar PV Immersion Heater Switch - Use Surplus PV Power to Heat Water, the same guys are behind the SolarImmersion (SolarImmersion ? Surplus Solar Energy Water Heater |) could do the charging on the electrical car. It have inbuilt DIN rail that can take a relay to extend the switch capacity (to about 50A). With that you could charge the electric car from your solar PV surplus.

Looks like Mark III / SolarImmersionfrom is similar to immersun, so can take only resistive load - so probably not suitable for electric car recharging.

 

[puddy]

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

 

[liquidity]

So if the sun doesn't shine today you're staying home tomorrow?

 

[puddy]

I feel cabin fever coming on if it rains all summer.

 

[JohnFW]

Hi Newbie here. 2 person + occasion 2 household. 4kWp PV array visited with lovely south facing 32 degree roof. Considering installing a prop controller and almost bought Immersun - then happened on this great thread - and found Solarimmersion. Not too impressed with their website - looks very thin. I wonder what their turnover has been and if they have many customers who have bought the MK I or MK II units. Anyone got any ideas on this one. Also, can u explain about the "burst fire" bit please

 

[JohnFW]

Sorry - for "visited" read "sited" !!

 

[Worcester]

Immersun is the largest selling unit (some would say I'm biased ) we have installed significant numbers of them.

I could be wrong and I'm sure that eChase will correct me if I am.

Burst fire mean that for 20% power the system allows one cycle in 5 through for 40%, 2 cycles in 5 (50 cycles per second) i.e a 'burst' of energy, they are full cycles swithed at the 0V crossing point, phase angle meanse that it allows 20%, 40% as prropriate of the area under the curve of a cycle, so switches on part way through a cycle and then off part way through a cycle. Phase angle has big issues with harmonics.

ImmerSUN is owned by 4Eco, a well established PV business that now focuses on their Immersun Product, and have sold thousands of units (we can tell from the serail numbers we get )

Can't tell you much about SolarImmersion except that the owning comapny is primarily a software design house Altobo | Corporate Portal
"Altobo Ltd was incorporated on 10 Dec 2008 and is located in London. The company's status is active, with one director. Altobo Ltd is split between 3 shareholders. They have no known group companies. Their book value is £-9,921, and the value of their shareholders' fund is £-9,921."

 

[JohnFW]

Immersun is the largest selling unit (some would say I'm biased ) we have installed significant numbers of them.

I could be wrong and I'm sure that eChase will correct me if I am.

Burst fire mean that for 20% power the system allows one cycle in 5 through for 40%, 2 cycles in 5 (50 cycles per second) i.e a 'burst' of energy, they are full cycles swithed at the 0V crossing point, phase angle meanse that it allows 20%, 40% as prropriate of the area under the curve of a cycle, so switches on part way through a cycle and then off part way through a cycle. Phase angle has big issues with harmonics.

ImmerSUN is owned by 4Eco, a well established PV business that now focuses on their Immersun Product, and have sold thousands of units (we can tell from the serail numbers we get )

Can't tell you much about SolarImmersion except that the owning comapny is primarily a software design house Altobo | Corporate Portal
"Altobo Ltd was incorporated on 10 Dec 2008 and is located in London. The company's status is active, with one director. Altobo Ltd is split between 3 shareholders. They have no known group companies. Their book value is £-9,921, and the value of their shareholders' fund is £-9,921."

Many thanks for prompt reply Worcester. Fully get the point now. Yes - I understand the problem with harmonics (used to be an electronic engineer many years back!). So if as echase says, the smart meter rollout could have hiccups with harmonics coming along, will those thousands of Immersun units run into problems? And how long before we get those smart meters anyway - can't see the government meeting its target by a very long way, so it looks as if my deemed 50% will be here for some while yet

 

[echase]

Those recent points cover a lot of different subjects like metering, EMC, safety, etc.

On the smart meter subject:

1) My understanding of these is that their purpose is to know hour by hour, or more often, how much the house is consuming. Then different tariffs can be offered to encourage users to use electricity at a time better suited to the DNO (utility company). Do any have auxiliary outputs to turn on certain loads at off peak times like the old dual rate electricity meters pre Economy 7? They also can read export so you could be paid for your export. But I see little evidence that this function will get used any time soon (and there are scant details about what the DNOs are going to do with the data they gather), by which time anyone buying a solar diverter type product for less than say £400 will have paid back their investment. Even if the 3 to 4p/2 payment for export is lost, it is still much less than the cost of heating that water with even a “cheap” gas boiler (assumed to be 7-8p taking account of the inefficiencies of short water heating cycles). So I don’t see smart meters having much impact on our economics just because of losing the deemed export payment one day in future.

2) I believe all electronic utility meters, including smart meters, are clones of a wheel meter and so measure the electricity in the same way. Thus small chunks of import or export and low levels of continuous power are ignored because a wheel meter will do. Some say the threshold is 10Whr (10J) but if you read specs for meters this fact is rarely or never stated. They seem very guarded about all this, presumably to stop people inventing devices to cheat the meter into providing electricity for free (not what these solar diverters are trying to do). So any solar diverter has to work in bursts of less than 10J, which is 1.2 seconds at 3kW.

On a burst fire controller trying to keep within the flicker spec you probably have to go slower than 1.2 secs (I did a more detailed version of above flicker calc and came out with needing at least one minute per burst), so can not meet both the flicker spec and keep the meter reading zero import/export. On a phase controlled device or PWM one, like the new EMMAs, there is no problem as they are operating at >=50Hz or <=20ms per “burst”.

A good electronic meter does internally measure thousands of times a second so it is quite capable of measuring in 1J or even 0.1J increments. As DNOs do not like burst firing for various reasons they could decide to change the increment, which would render any burst fire diverter useless. Only a DNO could tell you if they have any plans to do this, although I heard a rumour that some are thinking about it. Can they send a radio signal to ask the smart meter to change its increment or is it set for ever at manufacture?

On harmonics:

Not sure I said that smart meter rollout could have hiccups with harmonics; think I was referring to the above burst fire problem. As JohnFW will know, modern switched mode power supplies on TVs, PCs, etc, emit lots of harmonic current down the supply wires. So in many UK houses I would not be surprised if the total house harmonic current is high. It may not exceed the specified value, as this is expressed as a fraction of each device's load current. But added up across the house and all the houses connected to a substation it is a lot of harmonic current, which means that the substation transformer has to be oversized to cope with it. Adding one or two extra high current phase controlled solar diverters to this make no practical difference to the substation, if only because they can cause a different set of harmonics to a switched mode power supply. The harmonic current has no effect on the safety of the house or the neighbours. Hence electricians are allowed to make a choice to fit a device even if the harmonic spec is not met.

Harmonic current does not significantly distort the voltage waveform so nobody other then the DNO notices the problem and there is no inter device interference caused by it, as you get for high frequency EMI. It would only matter if lots of them were fitted per substation. Am I right about all this JohnFW?

So safety is not compromised by harmonics. But most hight current burst fire devices do affect safety as flicker is dangerous to epileptics, besides being annoying and causing disputes between neighbours. Also a badly designed PWM or phase controlled device can emit high frequencies so not be safe, but it is filterable fairly easily.

Don't think harmonic current has any effect on electronic utility meters as the meter successfully integrates the thousands of power samples per second to calculate the real power. All voltage or current distortions are correctly turned into a real power figure. Same is not true of cheap meters like OWLs, Current Cost, etc. as they make considerable approximations in their measurement techniques. Also I wonder if wheel meters struggle.

 

[mccltd]

I pre ordered the solarimmersion.co.uk new verion 3 unit after receiving a email from them and viewing their website but have got to say I'm getting a bit worried about them.
They haven't sent any email updates as they promised, they don't answer emails and out of 4 voice messages I have left with the global switchboard they use they have only returned one call of which the persion didn't know anything.
Has any one else had any better response from them?

thanks

 

[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??