Immersion Heater - PV electricity

[pauldreed]

If a Phase Angle Controller is able to restrict the amount of recorded power usage, would a simple series diode result in a 50% power reduction.
ie. does the electricity meter measure power usage over 180 or 360 degrees of the mains cycle??

 

[suntrap]

I would say yes, it records real power consumption, multiplying volts by amps continuously. That's what an analogue one does and a digital one would be designed behave the same or it would be naughty. Non-domestic meters measure VA rather than watts, encouraging customers to correct their own power factor/current waveforms.

 

[inie meanie]

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. :- )

 

[Andy_WSM]

Following this thread with interest as I am also on the look out for a device to divert my spare PV energy to my hot water tank.

 

[suntrap]

Well done on getting it going and it would be great to see a circuit diagram. However, one thing concerns me slightly:

Also to confirm that I have had NO interference generated by the triac effecting either the radio or tv (10pcv2425 contains a snubber circuit ).

I believe a snubber network is primarily to prevent the triac being damaged by high voltage ringing when it switches off. It is not sufficient to provide proper filtering of electromagnetic interference - for this you need a series inductor at least, as contained in light dimmers. You might not get interference on FM radio or TV, but you are very likely to hear it in MW or LW transmissons and it may become apparent on FM and TV when the wanted signal is weak.

 

[inie meanie]

Well done on getting it going and it would be great to see a circuit diagram. However, one thing concerns me slightly:



I believe a snubber network is primarily to prevent the triac being damaged by high voltage ringing when it switches off. It is not sufficient to provide proper filtering of electromagnetic interference - for this you need a series inductor at least, as contained in light dimmers. You might not get interference on FM radio or TV, but you are very likely to hear it in MW or LW transmissons and it may become apparent on FM and TV when the wanted signal is weak.

Yes this might be the case but IF there is some interferance I will add a circuit to resolve it. SO far so good :- ) No problems.

Hey Suntrap have you actually experienced any problems with interferance? As I havent seen any thing yet.

 

[suntrap]

I have experienced problems with interference from cheap switch-mode power supplies imported straight from China, which don't have input filters fitted - they wouldn't be allowed under EU emissions regulations. I haven't built anything like this yet so can't comment, but it may be that you are causing interference to your neighbours' equipment which you don't know about and which your neighbours won't know the source of. It could disrupt ADSL communications as this uses the lower frequency range. I can imagine that your circuit may severely disrupt power-line networking equipment, but that is very controversial with radio amateurs because it causes interference problems of its own!

 

[inie meanie]

Hi Suntrap. Well today I had the tv on the radio and my wireless router. No problem at all. I understand your concern and I will watch it very carefully. Do you have any suggestions for adding some protection? I would be happy to add it even if it wasn't required just to be on the safe side.

 

[suntrap]

I guess you'd look at circuits for light dimmers and see what they use. Unfortunately you'd need quite a hefty inductor to handle 13A though.

 

[Millerman]

Hi Suntrap
. Unfortunately you are under obligation to inform your supplier and they will change it after a month or so. :- )

My parents have had their system since last december. the electricity board came out and installed an isolator on the instructions given to them from the solar company. As of now they still have the old analogue meter good luck to them.