Immersion Heater - PV electricity

[suntrap]

Yes, it helps if no-one's there to mess up the consumption during the day! A diode will of course not do wonders for the current waveform but I agree is a very easy way to halve the heater's consumption.

 

[bradburts]

Do you have a link to the inverter with the relay?
Its sounds a good solution.
The diode would seem a lot simplier/cheaper than changing the immersion coil (which is where this thread started).
Does the inverter allow other power settings at which the relay switches? 1.8Kw seems quite a high threshold, I only go over 500W when the kettle goes on....
Would there be the problem with chopping out half the wave within a house?

 

[echase]

Hi,

Looking back at earlier suggestions; a light dimmer board was thought to be a simple solution, having all needed interference protection etc, but was rejected through having a potentionmeter control.
It may help to note that you could use digipots, digitally controlled potentiometers, to replace the light dimmer potentiometer. You would have to use a microcontroller to control the digipot of course but to my way of thinking the microcontroller circuit has got to be the best way forward with its meter, display and perhaps wireless control capabilities.

I will research and post suitable devices and provide programming examples if converting a light dimmers make electrical sense!

The device I have designed and am now selling does all this. Send me a private message if interested.

 

[echase]

I too am interested in getting an extra current transformer for my OWL, as I noticed the transmitter has three sockets on it (unless that's just for three phase supplies?). I haven't investigated it further yet, though.

I checked with OWL some weeks ago. It’s for 3 phase, but it just adds the 3 powers together and displays one figure so you can’t use it to display 2 or 3 different things like PV generation and export. Plus it has no idea of the direction of the current so an import and export read the same. The trick in any immersion control device is to discriminate them and my device does that.

 

[pauldreed]

Hi All, as I posted a few days ago, I have been working on version 2 of my solar controller, and it is now complete and fitted, so I thought that I would post a few photos.

The PCB contains the input filter and protection components, as well as the main processor and power supply stabiliser. The LCD display is recycled from an old alarm keypad.

Fitted it all into a small 'Maplins' project box after sawing a few holes in the lid and sides.

All wired up to the power supply and CT's, the first display screen shows the current power state, ie. how much power is being used within the home, and also how much solar power is being generated.

By pressing the button on the front, I can select different screens. This one shows how much power has been used/generated in kwh's. This total is culmative and resets every midnight.

Another screen displays the instantaneous mains voltage and power factor. This works very accurately, and is mostly within the tolerance of 1v to that recorded with a professional test meter.
The voltage measurement is what makes the power calculations much more accurate, instead of assuming that the mains is 240V AC.
As you can see here, it is currently 247V, but sometimes drops to just over 240V.

The small LED just above the button lets me know at a glance what the unit's status is;
1) flashing every 4 seconds - indicates that the unit is functioning, but not enough solar power to activate either relay.
2) steady but lit 25% - indicates that 500w is being unused, and activates relay 1, with a diode in series to limit the load to 500w (yes it does work, I've done the sums on the leccy meter!)
3) steady and lit brightly - 1kw power is now available, so relay 1 is deactivated, and relay 2 activated switching the 1kw load.

The device also provides a 0 - 5v variable output, which could feed a 'Crydom power controller' for progressive power control, which I may purchase at some stage.

 

[suntrap]

Fantastic. You must have spent ages doing that!

You could make the LED flash with every fraction of a kWh produced by the cells, like an electronic meter. Watching the LED flash beats TV any day of the week! When the relays are on, it could inverse flash (flash "off").

Pedantic note: your "w"s (watts) should be capitals :stuart:.

 

[pauldreed]

Pedantic note: your "w"s (watts) should be capitals :stuart:.

You are correct of course, amended accordingly!
The building time wasn't long compared to the learning curve, see post Immersion Heater - PV electricity - Page 3 and you will see that it's developed from that point forward with a lot of help from others, especially Home | OpenEnergyMonitor who have written most of the coding and been inspirational and confidence builders.
With the explosion of renta roof solar installations, similar devices are much in demand and I would encourage interested others to buy a Arduino Uno Arduino - HomePage and have a bash! they are great development circuits, and code is loaded directly from your PC without expensive programmers.
However, 240v is a very different matter, and is best left to the experts.

 

[Andy_WSM]

I am very pleased to say that I have completed my system. I have heated the top part of my tank very quickly. ( only as deep as the length of the immersion heater ) I raised water temp 10 deg before the solar water system had got up to temperature and started to circulate. This was important as some people have said this system won’t work quickly enough and this proved it is much faster than the water type system. Also to confirm that I have had NO interference generated by the triac effecting either the radio or tv (10pcv2425 contains a snubber circuit ). This system, just to confirm doesn’t use an expensive plc and follows the spare power level in an analogue way NOT waiting until there is a spare 1,2 or 3 kw before switching on in steps and thus wasting potential energy. It runs as soon as there is a spare 100 watts and continues to feed all the way up to full power 3kw. All it contains is a small comparison circuit made from 2 opamps ( 741, 75p each ). I triac crydom 10pcv2425 ( just bought one on eBay for £12 ) . A power supply that provides -12 0 +12 vdc, 2 current coils from LEM model AT20B10 ( £ 54 inc vat for the two ). I have fitted and extra dist board with a Henley block to separate the measurements. I now need to find a nice box to put it all in and maybe add a couple of voltage meters form eBay just to make it very easy to see what power is being supplied. The future improvements would now be to add another heating element to the bottom of the tank and a relay circuit to switch between the elements once the top one is up to temp. I hope this will encourage some of you to develop your system. It just goes to show there are several routes to achieve free hot water. :- )

Hi all,

Been liaising with Tony (inie meanie) and purchased a PCB off him for the control circuit he describes here. 2 current coils and crydom triac later and I too have a "spare power recovery" hot water system. I fitted the kit on Tuesday morning and haven't used the immersion heater at premium rates since. Today is a dull, cloudy, intermittent sunshine kind of day - I only have a spare 800w being generated, so to heat my water now would normally cost me 2.2kWh from the grid + the 800w generated locally. By using this cct I can just dump the 800W in for longer until the tank has reached temperature, then any surplus goes to the grid. I've really enjoyed this little project and will continue to enjoy the financial benefits it will bring

 

[echase]

Fantastic. You must have spent ages doing that!

You could make the LED flash with every fraction of a kWh produced by the cells, like an electronic meter. Watching the LED flash beats TV any day of the week! When the relays are on, it could inverse flash (flash "off").

Mine does that and also has an override to turn the immersion on if you want a top up on a sunless day. Some LEDs or an LCD are useful or else you don't know if the unit is working properly.

Looks like we have at least 3 viable solutions here. My one achieves the same aim as the others but I use cheaper components that are just as effective. The Crydom 10pcv2425 is pretty expensive (around £100) unless you find a cheap one somehow, as inie meanie did. So I went for a different approach that does not use such an expensive relay but provides the same function. My whole component cost including the box, current transformer, fuses, relay, processor board, etc. is less than just the 10pcv2425. On the other hand I am charging a modest cost for the design and for assembling it, as I don’t have the kit version available at the moment. My making them up saves you the potentially hazardous work of dealing with the mains side (but some of you are electricians so you don’t mind that).

I don't currently supply an LCD but am providing the connections for one as I do connect one to test and calibrate the units. I’ll make them available later for retrofitting when I get around to writing the full LCD software. LEDs provide much of the info that an LCD could supply.

 

[echase]

2) steady but lit 25% - indicates that 500w is being unused, and activates relay 1, with a diode in series to limit the load to 500w (yes it does work, I've done the sums on the leccy meter!)
3) steady and lit brightly - 1kw power is now available, so relay 1 is deactivated, and relay 2 activated switching the 1kw load.

Have you established that all electricity meters can cope with this half wave rectification? For the positive half cycle you will be importing from grid and exporting for the negative half cycle, or vice versa. As long as the meter successfully averages out the power over a few cycles this is OK but if not it will register an export or import when none really exists (apart from the error between the 2 discrete steps and the real power available for export).

 

[pauldreed]

Have you established that all electricity meters can cope with this half wave rectification? For the positive half cycle you will be importing from grid and exporting for the negative half cycle, or vice versa. As long as the meter successfully averages out the power over a few cycles this is OK but if not it will register an export or import when none really exists (apart from the error between the 2 discrete steps and the real power available for export).

I have only tested it with my meter which is a Ampy 5235 and it uses exactly half the full load.
The Ampy, as with most modern meters is fitted with a flashing LED, which flashes every Watt/hour recorded by the meter, so it is easy to check.
Simply count the flashes over 6 minutes and multiply by 10 to give you kWh's.
It's not as good a solution as using a linear power controller such as the Crydom, but it's a safe option (doesn't get hot and is well isolated from the low voltage side via opto isolators), and costwise, a 6A 400V diode costs 99p from Maplins, and a double relay module at £3.99 2-Channel 5V Relay Module for Arduino PIC ARM AVR DSP | eBay

It's great that we have got some solutions to this, albeit different routes, and hope more come on board!

 

[Mark Gee]

Great to hear there are 3 viable solutions.

Am having panels installed (tomorrow!!) and I'm not an electrician (although I dabble). I have a second CU that is already being used off one circuit to power an outside office/garage/studio

Am I correct in assuming that what I need to to 'future-proof' my system (for adding an immersion later) is to get the guys to do is
1. Install another CU (I won't do that)
2. Fit a Henley/Henly block

Is that all...if so I'll get down to Screwfix for the CU this afternoon! That's after I use the scaffolding (going up now) to mess around with the chimney stack and aerial...a bodgers work is never finished ;-)

 

[suntrap]

As I said in my posting, I'm OK with using the existing CU because there is enough space inside it to clamp a current transformer on a single core of the cable where the cores are split.

 

[pauldreed]

Great to hear there are 3 viable solutions.

Am having panels installed (tomorrow!!) and I'm not an electrician (although I dabble). I have a second CU that is already being used off one circuit to power an outside office/garage/studio

Am I correct in assuming that what I need to to 'future-proof' my system (for adding an immersion later) is to get the guys to do is
1. Install another CU (I won't do that)
2. Fit a Henley/Henly block

Is that all...if so I'll get down to Screwfix for the CU this afternoon! That's after I use the scaffolding (going up now) to mess around with the chimney stack and aerial...a bodgers work is never finished ;-)

Mark, who is the installer? is it a renta roof system (like mine).

 

[echase]

1. Install another CU (I won't do that)
2. Fit a Henley/Henly block QUOTE]

No, my system requires no wiring changes. It is useful if the immersion is on its own MCB in any of the CUs, rather than having other devices hanging off that MCB. But not essential.

 

[suntrap]

Another idea which wouldn't absorb so much spare energy but would probably save proportionately more money as it displaces eletricity rather than gas (in my case) consumption: get your freezer to run while the sun's out. ISTR that the instructions for mine say that you should press the fast freeze button (which just overrides the thermostat) 24 hours before adding non-frozen food, so there is some scope for lowering the temperature below normal and letting it recover at night, hopefully not having to run the compressor at all. (They are supposed to cope with power cuts of many hours if the door isn't opened.) Of course the lower the temperature in the freezer, the faster heat gets in, so it might be a good idea to put some limit on the lower temperature or it would become wasteful. Also, you must not switch the compressor off and on in quick succession as it won't start up while the refrigerant is compressed. (It sits there stalled until a self-resetting thermal cutout disconnects it, which is wasteful and can't be good for it long term.) You would therefore need a strategy involving a timer and starting at a higher threshold of spare power than what the compressor needs.

 

[Andysimm2000]

Hi All, as I posted a few days ago, I have been working on version 2 of my solar controller, and it is now complete and fitted, so I thought that I would post a few photos..

Brilliant stuff Paul - shows what can be done - I assume that this is the "display head" and you have the "guts" else where for the CT inputs and contactor outputs.

Are you prepared to release your designs free or for a fee?

Andy

 

[pauldreed]

Brilliant stuff Paul - shows what can be done - I assume that this is the "display head" and you have the "guts" else where for the CT inputs and contactor outputs.

Are you prepared to release your designs free or for a fee?

Andy

Andy, I have tried to separate the low voltage from the high voltage side, both electrically and physically, so yes you are correct, I have 2 opto-coupled relays housed separately to switch the high voltage (£4.20 delivered from Ebay).
The 4 CT inputs however are plugged into the USB socket, directly into the board.
So in effect, I have two boxes, one as shown in the photos, and another containing the high voltage stuff.
As for the design, well I have posted full build details here including PCB layout, and the programming sketch. No fee! but lets work together, share ideas and make it better still!

 

[inie meanie]

Mine does that and also has an override to turn the immersion on if you want a top up on a sunless day. Some LEDs or an LCD are useful or else you don't know if the unit is working properly.

Looks like we have at least 3 viable solutions here. My one achieves the same aim as the others but I use cheaper components that are just as effective. The Crydom 10pcv2425 is pretty expensive (around £100) unless you find a cheap one somehow, as inie meanie did. So I went for a different approach that does not use such an expensive relay but provides the same function. My whole component cost including the box, current transformer, fuses, relay, processor board, etc. is less than just the 10pcv2425. On the other hand I am charging a modest cost for the design and for assembling it, as I don’t have the kit version available at the moment. My making them up saves you the potentially hazardous work of dealing with the mains side (but some of you are electricians so you don’t mind that).

I don't currently supply an LCD but am providing the connections for one as I do connect one to test and calibrate the units. I’ll make them available later for retrofitting when I get around to writing the full LCD software. LEDs provide much of the info that an LCD could supply.

Hi just wanted to point one thing out. My device is analogue and therefore doesn't wait for a set amount before switching a relay and therefore wasting blocks of up to 500 watts at a time. Also no mechanical relays to fail and triac package is a neat pre manufactured device with built in snubber, so high voltage side is nice and proven and only requires a pair of wires to screw down terminals. Calculation side is all low voltage stuff. 12 0 12 v. Any cost savings on the front end will soon be lost in efficiency over the long term. My system works right down to just a few watts so I can heat water at almost any level of spare capacity. This forum has been a great place to share ideas and has pushed me on to complete the system. I too considered using a switching method but I didn't like the idea of exporting 499 watts before switching on the circuit etc, it could mean the difference between a hot shower or a cool one. I am so pleased with my ability to heat water at any spare capacity form the roof I will be removing my hot water vacuum tubes and fitting more pv

 

[pauldreed]

The difficulty with buying products/kits in these circumstances is that forum members are unable to assess what they are actually buying, especially in the case of echase who will not divulge his circuitry claiming 'copyright' and protecting his own interests.
I don't know if you have adopted the same approach inie meanie, but if not, why not publish your circuitry, photos of your device, etc. so more electrically savvy members may pass opinion, and thereby reassure other members. It also stimulates advancement and results in a better product for the end-user.
A few members may copy your ideas, but many would not be able to build the units, through ability or lack of confidence, and would be reassured by the open source approach.

I don't make or sell units for anyone other than myself, but I have openly published my work, which has taken many, many hours of my time to develop, and since publication, I have had quite a lot of feedback which has made my device better still.
Solar Power Manager | OpenEnergyMonitor

 

[inie meanie]

Hi Paul
I too have spent many many hours developing and testing, and I am at the stage of deciding whether to develop into a fully commercial product. I am currently investigating patents in this area. If I am not able to proceed I will produce a drawing and try to explain the calibration process. It's all moving a bit fast at the moment, But have been told not to show the circuit. I hope you understand.

 

[pauldreed]

Hi Paul
I too have spent many many hours developing and testing, and I am at the stage of deciding whether to develop into a fully commercial product. I am currently investigating patents in this area. If I am not able to proceed I will produce a drawing and try to explain the calibration process. It's all moving a bit fast at the moment, But have been told not to show the circuit. I hope you understand.

Yes I agree, but shouldn't there be a dividing line between a commercial product and a Open Source product?
If you go down the road of producing a commercial product, then customers would have the protection set out in law and you would have the patent protection, but with a Open Source product, it is a work-in-process which the responsibility and development is jointly shared.
With both echase and yourself, you appear to be neither, and yet are promoting your individual projects without any accountability.
Are both of you insured and willing to accept the responsibility of your designs, or are you encouraging customers to accept the products as 'developmental modules' with no 'come back' to yourselves?

Sorry to be blunt, but if houses catch fire through bad design/bad component selection, which way will you jump??

If it were not for those questions, I would probably market my own device!

 

[echase]

I am shipping some units to customers next week and am hoping they will be able to give an unbiased view here of the unit’s performance. That will I hope partially make up for my reluctance to publish the design here. Full marks though to Paul for his excellent and clear posting of his design. I think the only item I share with his is the same CT.

If anyone wants a more accurate clamp style CT I recommend the Magnelab units available from Rapid Online. But >twice the price. I have 2 on a commercial system that sends my PV statistics to a web portal so the installer and I can remotely monitor my system. High accuracy is not needed for an immersion controller but is for accurate energy metering.

 

[pauldreed]

I am shipping some units to customers next week and am hoping they will be able to give an unbiased view here of the unit’s performance. That will I hope partially make up for my reluctance to publish the design here. Full marks though to Paul for his excellent and clear posting of his design. I think the only item I share with his is the same CT.

If anyone wants a more accurate clamp style CT I recommend the Magnelab units available from Rapid Online. But >twice the price. I have 2 on a commercial system that sends my PV statistics to a web portal so the installer and I can remotely monitor my system. High accuracy is not needed for an immersion controller but is for accurate energy metering.

The unit's performance is not in question!
forget the clamp meter steer..
I am questioning the safety of the unit, can you state that this unit is safe, and if not, do you have the collateral to meet any compensation claims?
Has you're product been underwritten by an insurer?
I suspect not, and if so, how do you intend to deal with any any claims?

 

[TonyL]

I don't think there would be too many people who don't recognise the concerns you raise and the answer is pretty self evident. There will be a big difference between the insured position of a person who builds and installs a device and somone selling or supplying designs for a device.

The reference to Open Source would benefit from some clarification; Open Source code, designs etc are normally supplied as a licensed product under GPL. Google GNU GPL and you will find out all about it. GPL makes it clear that the item is supplied 'as is', without any warranty of fitness for purpose or other obligation. You take the good with the defect.

The common misunderstanding with GPL is that people do not realise the obligation they ACCEPT by virtue of downloading the item to publish their amendments and enhancements. Many people do just TAKE with GPL when in fact you accept an obligation to SHARE.

When I checked with my insurers about building and contents cover when having PV installed, the reply was simple; if I was using approved products supplied and fitted by an accredited installer in compliance with building regs then there is no issue other than to ensure the value of the insurance is upped by the amount paid.

 

[pauldreed]

I hope that I haven't upset too many people by asking 'pointy' questions, but they needed to be asked, and the absence of a reply speaks volumes....

 

[echase]

If that last post was pointed at me then I previously answered you by PM so you can’t say you got no response.

As a bit of an aside I question the legal framework we have in UK. If someone has designed something they can get that design to other people in several ways:-

1. Put it in full on internet either as circuit diagram/software or as a full design with drawings/pictures.
2. Put the “low risk” (e.g. low voltage parts) on internet and only hint at the “dangerous” parts, leaving the user to work out his own design).
3. Get a DIY electronics magazine to publish it.
4. Make up finished units and sell them.
5. Make up finished units but leave all the mains side to the user to wire up.
6. Get the product fully type approved and sell it.

No. 6 is clearly the safest way, but out of no. 4-5 and 1-2 which is safer? Anyone from an idiot to the best electrician/electronic engineer can take the design from no. 1 and 2 and try to make up a unit. As the design detail, especially in no. 2, is limited the end result could be completely unsafe and injure the person using the unit. But the designer is hoping that he is not blamable, especially in no. 2. But by failing to publish a good full design he is actually encouraging dangerous experimentation.

In no. 2 can it actually be said that the low voltage side is low risk? It could drive the output in such a way as to cause a hazard, e.g. cause a relay to chatter.

No. 4 gives the public good quality units and takes away the risk that an idiot makes up the design in an unsafe way. Also feedback from early users helps to improve the product. So it improves the safety over no. 1 and no. 2.

No. 5 transfers some risk to the user but does not improve safety over no. 4 as some may make a hash of it.

I have done no. 3 before with a design that had mains relays in it and the magazine said they checked the design (and made no changes) and that there is no real liability problem with this approach. But the user can still make a very unsafe unit by comparitively minor deviations from the publised design or by sloppy constuction, so it is not a particularily safe approach.

So in summary I contest that no. 2 is the least safe approach followed by no. 1 and no. 3, even though the designer is more protected from the law that under no. 4 or 5. This is not a fair application of law when the outcome is potentially more people being injured and not the intended less.

In another part of legislation the law recognises DIY electrical efforts in that initially it was proposed to ban all solder with lead in it, but I believe that an outcry from the DIYers left it such that it is now still OK in home built products.

 

[pauldreed]

I had hoped that we all could have worked together to develop something inspirational, but it appears that personal gain has got in the way.
So to the future.. I won't be posting here further, but if you want to keep up to date with the next generation of energy management, please follow me and other devotees at openenergymonitor

Good luck Guys...

 

[bradburts]

Thats a real shame.
The best way forward isto develop a solution within an open source framework - we all havecomplimentary skills and working together is the way forwards.
Onthe practical commercial level I find it hard to see where a company would find theROI to support development, testing and qualification as there areeither patents preventing us and/or our discussions have now limitedthe field for new patents (well done all!).
We are after alltalking about a very simple design, one that would be easy to copy,easy to add new feature too and then claim as original design. Thosepursuing the commercial route would need a patent or some magic otherdevice property (cost, features, company reputation etc.) in order tohead off alternatives. The fact that several here have developedtheir own system would tend to make this case. At a certain marketsize (which seems likely) some of those playing catch up willhave surface mount and will therefore trash all for cost andreliability whilst also having a company name which can be trusted.
Certainly there's a few pounds to be made selling kits or homers. At some point I suspect that runs foul of the law though.
I recognise though thatit must be hard though for some to share the design which they havesweated blood over.
Perhaps one area wecould all share in is the status of patent protection, which may inturn help understand the best way forwards.
The Emma patentLOAD MANAGEMENT CONTROLLER - Cooper, Timothy Patrick would seem to cover all the devices which we have discussed. PerhapsI am wrong, I would be grateful for a second reading and somediscussion. If I am wrong and there was a gap in the patentthen have we now prevented new patents through our discussion?
Personally I find itquite hard to accept the Emma patent. I am sure that I have readabout similar home energy management systems in the past. I have inthe past designed control systems which monitor supply and controloutput currents to match available power (battery chargers). Where isthe intellectual effort/novelty in saying finite resource would benefit frommanaged output control or that a closed loop system needs an input function and an output function?
Sunny Boy's homemanagerSUNNY HOME MANAGER. SMA Solar Technology AG capabilities would seem to overlap the Emma patent, wonder whatthat's all about.
To open the field toboth those seeking commercial gain and, to a lesser extent, free opencollaboration then we should post any references to articles whichpre-date and therefore may invalidate the Emma patent.
In my view the Emmapatent is simply too far reaching and may stifle the development ofenergy saving devices, whilst only providing an expensive solution.That cannot be good for the planet.
If Emma were innovativeto say £200 or so (the bits cannot cost more than £50 in volume)then I would be more inclined to believe some effort which justifiedprotection and a large markup return.
Perhaps the Emma engineers worked outside the open discussion forums and have a lot of NRE to recover.........

Finally this is a discussion forum we should discuss & share.
For those struggling with construction side should look at Renewable Energy UK where Niel has a 100 and 1 microcontroller / AC control systems at low cost, usually less than £30. Last time I looked he had a solar immersion controller (no diode) using an LDR rather than CT. They are all PIC microcontroller based. Think the software is often posted so should be easy to modify. Buy a control system, buy a learn to program a PIC book (its easy to learn) and I can support your code. Buy me a system and I will write the code for you.







As we all lack patentprotection (hopefully) then what would our individual business modelsbe?Lowest product cost, most product features? – that comes fromteams and the discussions we share here.
Sell low volumes to thehome enthusiast / kit market through the forums? Hardly seems worththe effort, especially considering the safety risk. I am sure thatthose involved are properly trained and highly skilled. There ishowever a reason why standards organisations require design reviewhowever, we all make mistakes sometimes. Anyway at the end of the dayall someone in China has to do is buy a kit , reverse engineer andmass produce in surface mount. Try proving that is your design then!

 

[echase]

it appears that personal gain has got in the way.

Good luck Guys...

All my sales income apart from the component cost and postage goes to charity so it’s not for personal gain. I am thinking of switching to kits from now on.

I commend those who want to pursue the open source route but beware your own safety.

 

[bradburts]

A kit is good. A kit with explanation and discussion even better!
IMHO offering a kits with explanations support an open development so long as copyright is not claimed. Others can then learn from the kit.
Better still sell the AC side properly built and boxed, that would leave others able to develop the digital side.
I would be keen for example on a AC proportional control module rated to 3KW and accepting, say, 0 to 5V demand with the demand appropriately buffered and isolated within the module.
On practical level I find it hard to see where a company would find the ROI to support development, testing and qualification as there are
either patents preventing us and/or our discussions have now limited the field for new patents (well done all!).
Commerialisation would be hard as we are after all talking about a very simple design, one that would be easy to copy,
easy to add new feature and then claim as original design. Those pursuing the commercial route would need a patent or some magic other
device property (cost, features, company reputation etc.) in order to head off alternatives. The fact that several here have developed
their own system would tend to make this case. At a certain market size some of those playing catch up will have surface mount and will therefore trash all for cost and reliability whilst also having a company name which can be trusted.

There was some earlier discussion on patents.
The Emma patent LOAD MANAGEMENT CONTROLLER - Cooper, Timothy Patrick would seem to cover all the devices which we have discussed. Perhaps
I am wrong, I would be grateful for a second reading and some discussion. If I am wrong and there was a gap in the patent
then have we now prevented new patents through our discussion?
Personally I find it quite hard to accept the Emma patent. I am sure that I have read about similar home energy management systems in the past. I have in the past designed control systems which monitor supply and control output currents to match available power (DC only). Where is the intellectual effort/novelty in saying finite input requires managed output control?
Sunny Boy's home manager SUNNY HOME MANAGER.*SMA Solar Technology AG capabilities would seem to overlap the Emma patent, wonder what that's all about.
To open the field to both competing commercial and, to a lesser extent, free open collaboration then we should post any references to articles which
pre-date and therefore may invalidate the Emma patent.
In my view the Emma patent is simply too far reaching and may stifle the development of energy saving devices, whilst only providing an expensive solution.
That cannot be good for the planet.

If Emma were innovative to say £200 or so (the bits cannot cost more than £50 in volume) then I would be more inclined to believe some effort which justified protection and commercial return.

 

[inie meanie]

Hi
I have obtained the pdf versions of the EMMA patent. If any body wants a read send me a private message with an email and I will forward it on. Tell me what you think. I personally dont want to get into any thing on the legal battle side as I cant aford to go head to head via laywers. :-(

 

[bradburts]

Hi
Tell me what you think. I personally dont want to get into any thing on the legal battle side as I cant aford to go head to head via laywers. :-(

I don't think we need to worry about lawyers right now.
Noone is going to take a home hobbyist on. I brought up the EMMA patent to settle the confidential design/commerical debate.
I would be keen to see the patent disappear though.
I am pretty sure that power control similar to the EMMA has been discussed before the EMMA patent. I may be wrong.
If anyone finds an article published before the EMMA patent then post. Thats pretty much all we have to do.
If we find the evidence then we will open up competition to those who know how, competition giving rise to improvements, hopefully cost savings, more improvements etc, etc. Once the systems are reasonably priced we can all just buy one rather than risk a home fire (Mr EMMA thats a market gap hint).
I am especially miffed about the EMMA patent as I had the same idea round the same time but through a number of reasons (thought it had been discussed before, was told that meters ran backwards etc) and a medical condition (bone idle) left it alone. Secondly the EMMA cost is really high.
I think that SB home system overlaps the EMMA patent which if so is interesting. SB seem switched on and seem to have a green home game plan. They have had digital interfaces in their inverters (bluetooth now) for a while. I think that may reveal a plan which may predate EMMA. Hoping anyway.

 

[TonyL]

I don't think we need to worry about lawyers right now.
Noone is going to take a home hobbyist on. I brought up the EMMA patent to settle the confidential design/commerical debate.
I would be keen to see the patent disappear though.
I am pretty sure that power control similar to the EMMA has been discussed before the EMMA patent. I may be wrong.
If anyone finds an article published before the EMMA patent then post. Thats pretty much all we have to do.
If we find the evidence then we will open up competition to those who know how, competition giving rise to improvements, hopefully cost savings, more improvements etc, etc. Once the systems are reasonably priced we can all just buy one rather than risk a home fire (Mr EMMA thats a market gap hint).
I am especially miffed about the EMMA patent as I had the same idea round the same time but through a number of reasons (thought it had been discussed before, was told that meters ran backwards etc) and a medical condition (bone idle) left it alone. Secondly the EMMA cost is really high.
I think that SB home system overlaps the EMMA patent which if so is interesting. SB seem switched on and seem to have a green home game plan. They have had digital interfaces in their inverters (bluetooth now) for a while. I think that may reveal a plan which may predate EMMA. Hoping anyway.

The EMMA people did a mailer via LinkedIn contatcs a few months back. I first contacted them last year so they must have picked it up from that. When I spoke to them this time, they said Mk II version is due out soon - I thinkk they said this summer but don't quote me on that - and it addressed the high cost issue.

Still waiting. I am absolutely convinced this is the thing to do with spare power but only at a reasonable cost. i.e. hundreds, not thousands. Will be very interested to see what SMA quote for their new peice of kit

 

[TonyL]

Actually, it really is just that despite the talk on the thread. EMMA is a switching device that allows PV surplus power to be directed to an immersion. Alternative devices are scarce and knowledge of them would be welcomed by all looking at this thread.

 

[bradburts]

Hi TonyL,
Not sure that I understand your post.
Are you saying that you originally had the idea for dumping spare PV power into heating?
Did you communicate via email?
The cost should be low hundreds. There is nothing complicated in this design, all the technology (as I would do it) is well established, its just a small control system really.
The component costs would be well under £100. The rest goes on development, marketing etc. A system could easily be developed & qualified in under 3 or 4 months, say £50,000 development cost. Plan to sell 500 so add another £100 to recover development. Add another £50 for support manuals etc. I just don't see the price tag.
Unfortunately the SMA system seems likely to cost £1000 or so.
Again I don't see where the costs come from but the system may be better featured.

 

[echase]

The EMMA people did a mailer via LinkedIn contatcs a few months back. I first contacted them last year so they must have picked it up from that. When I spoke to them this time, they said Mk II version is due out soon - I thinkk they said this summer but don't quote me on that - and it addressed the high cost issue.

...... at a reasonable cost. i.e. hundreds, not thousands.

Far as I can tell they are promising a new range called Cascade in Sept but it is for large installations so not addresing the cost issue for you and I. My unit is less than hundreds.

The SMA kit will only switch loads on an off so does not do close load matching.

 

[suntrap]

Noone is going to take a home hobbyist on.

Not only because it wouldn't be worth it but because there would be no legal grounds to do so. However, if anyone is using intellectual property covered by the patent to make money, they may well do, and I presume that is one reason why people here selling kits or complete units are being cagey about what their systems consist of.

As for home fires, well of course there is a risk, but if you are competent at electronics the risk is very small: if the relay sticks closed or the triac fails short circuit, it will merely supply full power to the immersion heater, which will switch itself off with its existing thermostat.

 

[echase]

No, cagey because I have some unique design features not used by anyone else so protecting my IP.

 

[suntrap]

So are you going to make anyone you sell it to sign a non-disclosure agreement then?

 

[old grouser]

I'm an idiot (in the Greek sense of not being one of you guys who understand electrics) but I do have a solar pv system and a conventional 3kW immersion heater, and I recognise that there is an obvious need for a system to store surplus electical energy as hot water. So there's an obvious need for some sort of switching/power reduction device of the sort you are collectively developing and discussing, and there's no reason why it should be particularly expensive, since (forgive the idiot language) it's really just an intelligent switch (I could do it myself if I sat in the airing cupboard all day with my Sunny Beam, waiting to turn on the immersion heater at those magic moments when the generation reached 3kW. Of course, it would be better if I could divert just the available surplus generation... but even I can see that this isn't an insuperable problem....). What is clear to an outsider is that there will be a sizeble market for this sort of product in, say, five years' time; that it's understandable that people would want to protect the value of their ideas; and that it's laudible that people should want to benefit us all by producing a collective, open source solution. Probably the commercial model will win; but it doesn't have to be patented. Volvo developed the 3-point seat belt, and deliberately didn't patent it. It's a commercially viable idea nevertheless. Lots of people make them. Presumably they all make a living from them. I hope that between you you'll produce a cheap, safe, viable and marketable solution soon, and that everyone will benefit. I'm impressed that you are trying...

 

[bradburts]

Not only because it wouldn't be worth it but because there would be no legal grounds to do so.

I think that the EMMA patent covers use of phase controllers.
inie meanie has downloaded the PDFs and I have posted links.
I would be interested in your and other's views as I am new to the language of patents i.e. do these patents cover a specific design or do the patents cover all designs, used in this PV context, which embody a phase controller?
Again I find it hard to understand how a patent may restrict designs which use well understood components, its would be like saying that a resistor were part of the patent claim and that therefore all solutions which use resistors are covered by the patent. Daft.
Anyway would be interested in views as the systems on offer are very expensive and competition (open or commercial) would be best.

 

[inie meanie]

I think that the EMMA patent covers use of phase controllers.
inie meanie has downloaded the PDFs and I have posted links.
I would be interested in your and other's views as I am new to the language of patents i.e. do these patents cover a specific design or do the patents cover all designs, used in this PV context, which embody a phase controller?
Again I find it hard to understand how a patent may restrict designs which use well understood components, its would be like saying that a resistor were part of the patent claim and that therefore all solutions which use resistors are covered by the patent. Daft.
Anyway would be interested in views as the systems on offer are very expensive and competition (open or commercial) would be best.

Hi Bradburts
Basically the Patent covers the principal of a household load management system that allows the spare electricity to be dumped into another house hold load. Ie. Immersion heater. I am not sure if this patent has actually been granted or is still in the applied format. If it still is in the applied state then there probably isn't too much chance of it being granted as so many other people are all working on other types of load management. It might be a bit of a scare tacktic to halt the competition.

 

[bradburts]

Hi,
U sure? M
y understanding is that the EMMA patent was registered 2 years or more ago. Others may work in this area now but as I understand it if the original first published 'design' is the patent then EMMA people have the rights.
I would be interested & very pleased to be shown to be wrong.

I have no experience of patents but as I understand it the patent falls if others have discussed similar designs before.
Please post if any such designs found.
I am sure that Star Trec have many episodes dealing with energy & load management (the crystals are always failing). Wonder if some solar powered space station attacked by klingons used load control. I'm off to check.
I'm working! I will tell the wife as I go through the last 40 years of scifi.

 

[old grouser]

I don't know much about electricity - I assume it's like plumbing but with smaller holes for the electricity to pour through - but it has just occurred to me that I do have an old friend who is an intellectul property lawyer. I'll try to get him to look at this thread and report back. (This may take some time...keep on inventing solutions...)
OG

 

[bradburts]

That would be great.
I have been researching some more & the following seems relevant:
1) (1974) Load management detailed in U.S. Patents 4,241,237 and 4,455,453 and Canadian Patent 1,155,243 (Apparatus and Method for Remote Sensor Monitoring, Metering and Control)
2) 'Smart grid' as used in 2005 "Toward A Smart Grid", authored by S. Massoud Amin and Bruce F. Wollenberg appeared in the September/October issue of IEEE P&E Magazine (Vol. 3, No.5, pgs 34–41)
Seems to me that the EMMA system is a form of 'economic demand response' that is to say it costs you nothing to use the PV and costs you to use the grid. Selecting one supply or the other is therefore an economic demand response.
I was very happy to find that load managment has been discussed since 1974. I think therefore that there is nothing to worry us in the patent, just the difference between macro and micro grids.
I also found reference to office lighting systems which dimmed as a response to grid load.
http://www.lrc.rpi.edu/resources/newsroom/pdf/2004/LoadShed.pdf
I suppose therefore/also that I/we could offer systems which dimmed lights (say a 3KW system for those with big houses) when PV output was low & before we start to tax our fragile grid.
The light is not an energy store (as discussed by EMMA) and light dimming has been done before, see link above.
Of course I would be powerless to stop someone fitting the dimming device to an immersion heater..........


Think inie meanie was right. Would be great to have a proffessional's view though!

 

[suntrap]

The difference between patent theory and practice is that even if a patent is ultimately invalid, if the company holding it decides to prosecute you because you are selling a product that infringes it, you could spend a large amount of money defending yourself in court.

 

[bradburts]

The difference between patent theory and practice is that even if a patent is ultimately invalid, if the company holding it decides to prosecute you because you are selling a product that infringes it, you could spend a large amount of money defending yourself in court.

Agreed.
I hope however that as the prosecuting company would need to spend money they would not, especially if there is a lot of 'holes' on clear display!
I will post as many 'holes' as I can find and hope that the wiser explain their validity.
I hope that somewhere along the line someone will think that the route is open for their own system to go to market but at a much lower cost.

BTW, old growser,
You're right, the control systems being discussed are quite simple. A microcontroller monitors both PV generation and home use using a pair of current transformers. The microcontroller then controls the amount of power going to the immersion heater using a phase controller. A phase controller is a posh name for the circuit in your light switch dimmer, it works by switching the AC on some way into each AC wave cycle and therefore limits the amount of power being transmitted in each cycle.
Some are using simply relays which have the advantage of being even simplier to design. The problem with a relay solution is that a relay cannot be switched on/off within the AC wave and therefore a relay will clock any meter at the relay's load's rating, typically 3KW for an immersion. The relay's PV generation trigger point must therefore be much higher than the phase control system. Using a lower watt immersion heater lowers this threshold but at cost and hastle. Adding a diode in series would reduce the 3KW to 1.5KW. Your trigger point PV generation would then be, say, 2KW, 1.5KW for the immersion and 0.5KW for the home.
You're right you could be the control system by sitting in your airing cupboard, with unemployment and energy prices going the way they are you may be able to employ someone to do this, start a company and see if you can get an intern! Technically you would be open to prosecution (if you think that the patent is valid) though as 'a switch' is described in the patent, the patent also covers Thyristors which suggests use of a phase controller (which is just a more advanced switch synchronised to the AC waveform).
Most in this forum (it would seem independently arrived at design that) think that a phase controller would be the best way to go. By far the most effective system is a phase controller as it allows you to control power dumping with a high level of resolution thus sucking up all the excess power rather than having to reach a generation threshold related to the immersion heater's power rating.

 

[suntrap]

Phase controllers (despite my intention to use one) have two disadvantages:

- they generate heat
- they generate electromagnetic interference, which to suppress properly (i.e. to comply with regulations for a commerical product) is bulky and expensive for this sort of current

Actually, aren't there regulations stipulating that power factor correction is needed on any appliance drawing over a certain amount? This would add even more to the cost. And the use of a simple diode to reduce power consumption by half would also need power factor correction in this case.

There's no reason why an immersion heater controller should need to sense both house and PV current; if it gets a sniff of the voltage waveform you can tell which way the current is flowing in a meter tail so one current transformer is all you need.

 

[bradburts]

Hi suntrap,
Having just one CT would be a nice simplification.
Forgive my ignorance but how would you sense the direction by looking at the voltage waveform?
Your right power factor will drop. I recently scanned the low voltage regulations looking at CE marking but did not see anything about power factors. Do you have a link?
I agree heat could be an issue. I gather that Rds values can be really very low these days though.
RF is always fun. Best bet with RF is to sacrifice a cat under the full moon, that’s what the RF engineers I know do, I'm sure.
What do you think the EMC problems would be?
I am not sure that there would be a major EMC problem though.
I have read a few application notes and have not seen any mention of EMC, the application notes are very detailed as well (enough for a softee like me to understand!).
Also I don't remember the EMI rules forming a distinction between continuous emissions and discrete and a relay switched on or off would chatter albeit for a short duration.
A phase controller would pulse giving you a step at 50Hz for sure.
13Amps is a lot to switch but how many multiples before we get to a regulated band?
Have you done any calculations? Is the simple on/off at 50Hz circuit in the face of the standards or marginal?