Immersion Heater - PV electricity

[delleray]

Interesting thing, that power halver, though I'd wait to see how much the 3kW one is as it would mean the standard/existing element could be used......

I have used a single diode out of a MB356 BRIDGE RECTIFIER 35 Amp 600V (£2.79 posted from polarity_electronics_uk on ebay ) to halve my 3Kw immersion load. Its AC input feed is relay switched in with a wireless remote when the output from the PV exceeds fixed amount.

It gets warm but not hot as it's only having to dissipate < 10W so is mounted in a double wallbox with cooker isolating fuse/switch.

A similar unit could be used to half feed a 750W oil filled radiator.

Will try the CT differential phase control technology mentioned elsewhere when I have time...

d.

 

[thushar]

Have found a similar unit to power monitor on ebay : Business Building Kits items in Fair Trade Hub Shop store on eBay!

Hope it will be help to resolve your problem

 

[suntrap]

You mean a lower power heating element? Problem with those is that you then lose the versatility of the high power original if you need it. Advantage over diodes is that it doesn't mess up the mains current waveform.

A tip to delleray: use two diodes in parallel from the bridge (connect both AC terminals together) to reduce heat dissipation and increase reliability marginally.

 

[thushar]

Not the immersion heater. The link ( Business Building Kits items in Fair Trade Hub Shop store on eBay! ) does have an immersion heater control switch, which monitor the output of the PV and turn on the immersion when enough power is available .

 

[suntrap]

Oh you mean this? As you say, it only monitors PV power rather than exported power, so is really not a satisfactory solution because as soon as you turn on a kettle you will start to pay for the immersion heater.

 

[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.