Immersion Heater - PV electricity

[thushar]

Yes. they are good enough to use when the house is in standby - When no one is in the house. Working fine for the last one month with my install. It leaves 500W for the in house use - So will turn on the immersion automatically at above 1.5 kW PV production. I'm getting full tank of 60C ho****er even in feb with this setup- boiler hardly runs.

I have a immersion switch as well, will turn it off during weekend when washing machine is on.

 

[sharpener]

A bigger tip to delleray: it's illegal to do this because it puts a large direct current back down the mains. Someone else has posted the actual permissible limits, but you can be sure an immersion heater exceeds them by a very wide margin.

It's also dangerous for you because ordinary Residual Current Devices (ELCBs) don't work with a large d.c. component to the current, so you and your family will not be protected against electric shock any more.

For both these reasons it is preferable to use a step-down transformer e.g. a 240/110V site transformer to reduce the power to the immersion heater.

 

[bommels]

If you want to go the transformer route, you might want to consider these:
BLOCK Transformatoren-Elektronik GmbH :::: Products :::: Transformers :::: Product Details
Although an autotransformer would be good enough for the job, the price still lies between £130-160. But that is the price for smooth waveforms, I guess!

 

[Plotty]

Hi all,

Found this site via a PV thread: my eyes did glaze over as I waded thru all 44 pages.

I'm not an electrician or an engineer, nor am I interested in this field - I just want to use my free electricity to heat my hot water (apologies to those who think that's not green). However ...

it would seem to me that if a device monitored the pulse on the import meter so that it only switched on the immersion circuit when you're NOT importing, that would allow any excess PV electricity to be diverted to the immersion. (or is that too simple an idea?).

BTW, echase, claims for your system appear interesting, but there's too much secrecy to give me confidence - even your customers on this board are not willing to discuss something a simple as the price??

Would be good to hear about Sparqui's progress with that solution (post 338).

 

[echase]

Hi all,

I'm not an electrician or an engineer, nor am I interested in this field -

BTW, echase, claims for your system appear interesting, but there's too much secrecy to give me confidence - even your customers on this board are not willing to discuss something a simple as the price??
QUOTE]

This forum is mainly for people interested in sharing design ideas for solving this issue. I respect that so don’t clog what is already a very long and interesting thread with adverts for my design and I ask people who have my units not to do so either. Happy to receive Private Messages on it though and give out testimonials that way. I supply people with at least some electrical or electronic engineering expertise. It’s not for the beginner.

 

[old grouser]

Just found this 27" 2 1/4" BSP thread 1 kW immersion heater in ebay -
1 kw / 1000 W 27" Immersion Heater - Use Spare Solar Panels Power For Heating | eBay

Hope that will help

Similar available from Surejust | Manufacturing equipment for the marine industry for over 25 years -and at about the same price.

OG

 

[suntrap]

Similar available from Surejust | Manufacturing equipment for the marine industry for over 25 years -and at about the same price.

OG

Are they the same length though?

 

[Sparqui]

Plotty,
I have successfully created a remote monitor with a repeater in the kitchen which actually tracks my turning loads on/off and I have created logic to give a ramp up/down signal for a thyristor circuit. I had a false start when I bought a cheap 4 way 433MHz remote control and have since identified a more professional encoder/decoder transmitter system.
I have used the monitor mainly to confirm/justify putting tumble dryer etc on in the daytime while I've been at home. I created a hard wired link to a crude controller circuit with electric kettle (and light so as to see dimming effect) and proved to myself that the concept worked but needed some tweaking in the feedback loop, it was more on/off than dimming, but i know where to go to sort this now

My work has stalled as a result of re-entering the world of employment and lack of sunshine in theevenings to test it by.
I have a dilemma as whether to patent this, with searches costing ~£3k, find someone to develop this with me, or just publish and be damned so that the design is in the public domain.

Hi all,

Found this site via a PV thread: my eyes did glaze over as I waded thru all 44 pages.

I'm not an electrician or an engineer, nor am I interested in this field - I just want to use my free electricity to heat my hot water (apologies to those who think that's not green). However ...

it would seem to me that if a device monitored the pulse on the import meter so that it only switched on the immersion circuit when you're NOT importing, that would allow any excess PV electricity to be diverted to the immersion. (or is that too simple an idea?).

BTW, echase, claims for your system appear interesting, but there's too much secrecy to give me confidence - even your customers on this board are not willing to discuss something a simple as the price??

Would be good to hear about Sparqui's progress with that solution (post 338).

 

[Richchad]

Plotty,
I have successfully created a remote monitor with a repeater in the kitchen which actually tracks my turning loads on/off and I have created logic to give a ramp up/down signal for a thyristor circuit. I had a false start when I bought a cheap 4 way 433MHz remote control and have since identified a more professional encoder/decoder transmitter system.
I have used the monitor mainly to confirm/justify putting tumble dryer etc on in the daytime while I've been at home. I created a hard wired link to a crude controller circuit with electric kettle (and light so as to see dimming effect) and proved to myself that the concept worked but needed some tweaking in the feedback loop, it was more on/off than dimming, but i know where to go to sort this now

Isn't this a similar device that monitors the flashing generation meter light to help decide if to use spare electricity... or am I getting this completely wrong and there is more to it than just monitoring?

GEO SOLO PV Solar Energy Monitor

 

[Plotty]

Hi Sparqui,

Thanks for the update. Pleased that you're back earning. Now that we're moving towards longer days, I hope you can finish your testing. I'm in the market for one that I know works and won't burn my house down.


Richard

I too have a Solo PV but this just monitors the gen meter output. However, the same technology could monitor the import meter LED and only divert the excess PV leccy when you're not importing. I assume that in addition to monitoring your import meter, it'll also need to monitor your consumption to work out when you have excess. Or it could just monitor both import and export meters and do the maths. The only proven device I know that can do this is the EMMA, but it's not a feasible option for me at c£2K. Others on this board also appear to have solutions: echase - he had my hopes up but his reply speaks volumes; Paul; & inie meanie.

Me, I'm after a solution I can plug in straight from the box or get my electrician to fit.

 

[Richchad]

Thanks for the reply Plotty, I haven't got the Solo PV but was thinking of buying it to give a more visual display of generated electric, is it any good?

I have also looked at the EMMA and that is exactly what I want but not at their price... lol

With the PV growing market, although maybe slowed somewhat by reduction in FIT, there must be a market for what we are all looking for, a box to either fit or get someone to fit that does what the EMMA does at a much more competitive price, like less that £200..... :smiley2:

 

[Sparqui]

Richard et al.
Thanks for that, saved me a patent search I'm sure! I spent ages last year searching internet for EMMA alternatives and could find no other device. My device monitors the meter LED in the same way (but is hard wired back to repeater LED in kitchen). I have no need for digital display as my ultimate aim is still to use the flashing import or steady export state of the LED to control a 3kW dimmer so as to mop up any excess PV electricity by dumping it into the immersion heater - whether there is anyone at home or not. I estimate the component cost to make at home to be about £50 max, but I will not market it commercially because of the mains implications. However, the simple hard-wired LED repeater, using a spare USB PSU, one photo transistor, one transistor, one LED and about 3 resistors - only cost about £5. It is watching this that tells me if I can switch appliances on or off. It is fairly easy to judge what the consumption is since one flash represents 1Wh so one per second is 3600kW.

 

[echase]

Richard et al.
my ultimate aim is still to use the flashing import or steady export state of the LED to control a 3kW dimmer so as to mop up any excess PV electricity by dumping it into the immersion heater - whether there is anyone at home or not. I estimate the component cost to make at home to be about £50 max. It is fairly easy to judge what the consumption is since one flash represents 1Wh so one per second is 3600kW.

Think you will find it not so easy as you think. If you try to control down to say 100W accuracy the flash rate will then be only 1 per 36 secs. You need to let a few flashes go by so you are sure you are measuring it accurately. So you can't respond to small changes in power in less than a few minutes. Plus if the LED is not flashing for export how do you know it's exporting 1W or 4kW?

The SSR needed to do this may on its own be more than your £50.

 

[Sparqui]

Think you will find it not so easy as you think. If you try to control down to say 100W accuracy the flash rate will then be only 1 per 36 secs. You need to let a few flashes go by so you are sure you are measuring it accurately. So you can't respond to small changes in power in less than a few minutes. Plus if the LED is not flashing for export how do you know it's exporting 1W or 4kW?

The SSR needed to do this may on its own be more than your £50.

As soon as I see a flash, I ramp the power down, plus built in slow downward drift to cater for loss of communications. When seeing continuous LED, ramp up again, slowly, stopping when no LED. Ultra cautious, but for the money a marginal loss in maximum power usage. My £50 was for one-off component prices, building for myself. The trick is in getting the control loop gain and damping correct. My first attempt was too crude, resulting in a simple on/off cycle of about 10 seconds. I Know where I went wrong and is now a matter of breadboarding this - I could have done with another month's redundancy :icon9:!

 

[Fazzathebrave]

here is schematic for control loop. I haven't finalized the +- 15v supply components so haven't included them will post full schematic when finishedView attachment 8187

hi pmcalli. Many thanks for posting the circuit. I think it's a lovely simple solution to get the job (of not exporting) done. I wondered if you have updated the circuit diagram to show the +- 15 v supply and a parts list? I was hoping to go and buy the bits to build it.... panels being installed Tuesday! This whole thread has taken me back to the electronics degree I completed 22 years ago. No

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