Managing and using your generated power - a whacky idea?

[ProDave]

Yes the old disc meters run backwards if you are exporting, so your "normal" electricity bill counts down.

This effectively means anything exported earns you another 13p per unit.

Keep quiet about it. It's not your "fault" and you are not doing anything "wrong" But you obviously have a lot less incentive to do anything to use your generated power in real time, because the nice DNO are effectively giving you 100% efficient free storage of what you generate.

I'm surprised there are still disc meters in use, they must all be quite old now and I though meters had to be changed regularly. I would also have thought the DNO's would as a matter of course go and swap out any disc meters where solar PV was installed.

 

[ProDave]

Well my solar PV dump seems to be ticking along nicely.

265 minutes dump time seems to be my limit, which equates with my 700W heater to be about 3KWh of electricity "saved" from being exported. There's not enough power before about 10:30AM to trigger the dump load to come on, then after 5PM the same, not enough power as the sun's getting too far round.

So that's a "window" of about 390 minutes when the dump load could come on if nothing else was using power, so considering most days there's a dishwasher load and a washing machine load (and often that pesky tumble dryer) I think it's doing okay.

And the holy grail was achieved today, the immersion heater reached temperature and cut off BEFORE we ran out of sun, and at 5PM when the boiler time clock turned on, the boiler didn't fire up as the tank was up to temperature already.

I'm just working now on some data logging to record the On time each day. the on board eeprom should be able to store 500 days worth of data before rolling over and over writing previous data.

Am I allowed to mention it's been warm and sunny here for a few days? I hear some of you are getting a bit wet.

 

[steptoe]

its been part P-ing down round these parts Dave,

glad to hear you are getting it to work the way you want,

 

[binky]

I have 2 customers with old wheal type meters, both run backwards and one now has lower leccy reading than the last reading in Febuary - quids in :^O

 

[ProDave]

I'm surprised the energy suppliers are not rushing around to every property that registers a microgeneration system to replace the wheel meters, with digital ones.

Failing to do so is costing the energy company money.

 

[NozSpark]

I'm surprised the energy suppliers are not rushing around to every property that registers a microgeneration system to replace the wheel meters, with digital ones.Failing to do so is costing the energy company money.

You are kidding aren't you?

When has anything like this cost them money? It's all factored in and passed on to the rest of us

 

[ProDave]

You are kidding aren't you? When has anything like this cost them money? It's all factored in and passed on to the rest of us

Of course it IS costing them money. If they had a modern electronic meter that didn't run backwards when exported, then the customer would have a higher electricity bill = more income for the energy supplier.

 

[kme]

I agree with you in principle; but I think Nozzer`s point of view is that the companies have already allowed for these percentile losses due to older meter; and included it in one of last year`s price increases to all customers! So they aren`t making the money they could be; but they don`t care!

 

[brummydave]

Worked on just such a system few weeks back with a homemade changeover switch with override for the not so sunny days.Company called Chris Rudge Renewables in seaton, devon. Reckon hed sell the changeover boxes seperately

The changeover boxes are available, but for

 

[ProDave]

Okay I want some forum input now.

I'm wanting to take this little project to the next level, i.e to work out how to package it for others to use.

My prototype one has the rather odd arrangement of having the electronics in my office next to the consumer unit but the contactor that switches my immersion heater, and the 110V transformer that turns it into a low power immersion heater are upstairs in the airing cupboard.

If one were to package this unit for others, it really needs to be all in one box and using a SSR instead of a contactor.

So one box, mains in, switched mains out, and a socket to plug the current transformer in to.

In a correctly wired house, that would work okay. you would need an electrican (or be competent yourself) to take the immersion heater circuit from your CU, into the dump controller, and the output from the dump controller back to the immersion heater circuit. And the user would have to make arrangements to either fit a low power heating element, or fit a suitable transformer.

What ideas / problems can you contribute?

 

[Sidewinder]

Can be done Dave, but a heck of a product "acceptability" system to go through.

It would have to meet the LVD, the EMC directive & various A, B & C standards.

It is not insurmountable, but, it could cost a significant amount.

Perhaps you are better removing all references and keeping schtum, then trying Dragons Den!

 

[NozSpark]

Or patent the idea and then try and sell it under license????

 

[ProDave]

I was looking for suggestions on what features are needed and now it should be packaged, not help on the EMC directive. While it remains a one off home built prototype it's exempt from that.

One other feature I can think of is a switch to set the dump load turn on threshold to suit the load you are using it with. My own has that hard coded which is no use if you are not set up or don't know how to alter the code.

 

[Sidewinder]

Sorry Dave,

I took it as that you were thinking of developing it for sale!

For you to develop & use it in your home for your personal use is up to you, the only people who can have a say in anything are your house insurers really.

I'll have a re-think.

 

[NozSpark]

I think he is looking at developing it for sale TBH Sidey (reading between the lines)

 

[paulca]

Hi All, I just found this thread and it's exactly what I'm trying to do. I already have an arduino hooked up to control my main CH zones, Could do with some help finding the right CT clamps .... been on ebay and there's thousands to choose from. Also could do with some advice on where to put them to get the correct usage / generation readings.... Actually thinking about it I could do with a circuit diagram on how to connect them to the Arduino analog inputs.....so

(a) Where to get the right kind of clamp from (for the right price)

(B) Where to connect these to the CU / Inverter

© CCT diag of Arduino analog inputs

Any help gratefully appreciated.

Also Dave, do you live in Orkney or was it just a holiday ?

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Just seen these on ebay .... will they do the job ?

Non-invasive AC current sensor SCT-013 (30A max) | eBay

 

[binky]

For anyone planning a PV install and wishing to achieve control of an electrical item like an immersion I would suggest fitting a Fronius IGTL inverter. These are fitted with a 12V relay that can be programmed via the 'Energy Manager' and used to trigger a 240V relay. Just done this and it's relativel simple to achieve.

 

[ProDave]

The trouble with using the inverter to turn on a dump load, is that it doesn't take into account any other loads in use in the house.

The current transformer is this one SCT 013-030 3.5mm Output Split-core Current Transformer | eBay

You will need to open it up and disconnect any built in components (I think there was a built in load resistor) leaving it as a bare transformer, and you build your own load resistor in when you build your own circuit.

Connecting it is easy, I just used a 150 ohms load resistor in parallel with the output of the transformer, and you then connect it to any analogue input on the arduino

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(Having to make a NEW post due the the ridiculously SHORT edit time window)

The current transformer clips around the L meter tail between your meter and consumer unit(s) so it measures all power into and out of the house, and by making a voltage measurement as well can work out the phase and so determine if it's imported or exported power.

 

[binky]

Having run my own PV for 6 months now, I increasingly find it difficult at this time of year to use leccy generated. So dumping to immersion seems like a good idea, even if other appliances are running?

 

[Borwick]

A very interesting thread as I am planning something similar.

Top of the list, I was thinking about acquiring a site transformer to drop the voltage on my immersion heater to 110v. The advantage being that if it doesn't work well then I can just put it back on eBay. Does anyone have any views on the specification of site transformer which would be best to work with a standard 3KW immersion heater element?

Now, I am just a country boy and would welcome some help, However, I remember P = I.V and it occurs to me that if I use a transformer, then the power in will be the same as the power out, save for some percentage loss and heat etc. So, even though I have changed the voltage of the supply to my immersion heater the power will stay the same but the characteristics will change so there will be more current drawn by the element. Am I right about this? If so, transformers won't help us when trying to reduce the power consumption of an immersion heater.

The other route seems to be to use an electronic solution to "chop up" the AC current so that only part of the power is available to the immersion heater element. I have heard that such solutions can cause problems with other sensitive electrical equipment nearby. Has anyone had any bother with this.

many thanks.