For anyone that might be interested or is curious to know the differences in functionality being employed out there - Technology Overview
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Re: Propotional Controller Technologies
it's why we pretty much stopped installing them - just done a couple since in areas of low grid impedance where the flickering shouldn't be an issue.
unfortunately that means the installation is unlikely to be compliant with the flicker regulations, and it's likely to also impact others on the same phase.
it's why we pretty much stopped installing them - just done a couple since in areas of low grid impedance where the flickering shouldn't be an issue.
There's pros and cons to burst and phase-angle control. These are typically easy enough to overcome in an industrial environment where industrial norms apply. Not so easy to comply with domestic CE (discounting self-certification) & EMC norms though....
Interesting stuff Andy
How about a list of which available controllers use what method.
From your experience, which are likely to comply with flicker regs?
How about a list of which available controllers use what method.
From your experience, which are likely to comply with flicker regs?
Hmmm, I'm cautious of being overly commercial here tbh but this document might help to outline who uses what. I'm also conscious of the fact that the Greenologic Power Reducer launch has been delayed although this is simply due to their commitment to being 100% compliant with domestic and industrial CE/EMC norms....
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Really? And why have they changed their technology??
because I pointed out 7-8 months ago that it was none compliant, and after a bit of head scratching they said they'd have to work on a fix for it - this was after we'd originally reported an issue last Autumn and been assured it wasn't a problem.
I also gave them some ideas of ways they could at least ensure that it wasn't installed in non-compliant situations via either proper impedance tests, or just monitoring the voltage change as a 3kW load was switched on and off, as a stop gap measure to ensure the unit wasn't installed in non-compliant situations, but they obviously preferred to not publicly acknowledge the issue rather than warning installers about it and giving them a simple method to ensure compliance.
None too impressed tbh that they continued to sell in volume while knowing it wasn't compliant in a small but significant number of situations, which is a shame really as I found the team there to be pretty helpful generally.
Uhuh...indeed Gavin. I don't particularly want to comment any further on any specific product that we don't already stand by so I'll keep my input on this thread technical/info only.
I probably shouldn't have either, but they've left installers and customers open to legal issues and possible DNO action, as well as the potential for epilepsy sufferers to have that condition triggered by the flickering lights their non-compliant system causes in high grid impedance situations, so I'm a bit narked with them tbh.
S
solar warrrior
Gavin
Plenty of others narked with them too for selling so many of their dubious units when there are better products available. There are some phase controlled units that are well filtered so are compliant despite what some may claim here. Greenologic http://www.greenologic.co.uk/SharedFiles/Download.aspx?pageid=176&mid=258&fileid=90 state that with filtering it is possible. Mind you there are other phase controlled products that have little/no filtering and so should not be sold. One I have seen has no more than one small snubber capacitor on its output to provide filtering. Useless.
I would have thought the majority of houses have too much impedance to use an Immersun on although suspect that many are close enough that no one notices the flicker unless it is pointed out to them, even though technically there is more flicker than allowed. What proportion of houses do you think it is not legal in? Lots of posts here about Immersun and flicker and they have never tried to defend themselves as far as I can see because it is indefensible.
I wonder if that buzzing MCB was one of the ones that should have been recalled a couple of years ago but was still installed. I forget the details but a major supplier recalled a large batch of them.
One thing Greenologic do not mention is PWM also gives out considerable EMI. But it is of such a high frequency that it can be suppressed by screening the cable between the controller and the immersion. That is added expense and imagine having to recable a long route to the immersion with screened cables. At least that is what the EMMA people have found I believe on their PWM system. It is all adding up to quite an expensive solution???
Plenty of others narked with them too for selling so many of their dubious units when there are better products available. There are some phase controlled units that are well filtered so are compliant despite what some may claim here. Greenologic http://www.greenologic.co.uk/SharedFiles/Download.aspx?pageid=176&mid=258&fileid=90 state that with filtering it is possible. Mind you there are other phase controlled products that have little/no filtering and so should not be sold. One I have seen has no more than one small snubber capacitor on its output to provide filtering. Useless.
I would have thought the majority of houses have too much impedance to use an Immersun on although suspect that many are close enough that no one notices the flicker unless it is pointed out to them, even though technically there is more flicker than allowed. What proportion of houses do you think it is not legal in? Lots of posts here about Immersun and flicker and they have never tried to defend themselves as far as I can see because it is indefensible.
I wonder if that buzzing MCB was one of the ones that should have been recalled a couple of years ago but was still installed. I forget the details but a major supplier recalled a large batch of them.
One thing Greenologic do not mention is PWM also gives out considerable EMI. But it is of such a high frequency that it can be suppressed by screening the cable between the controller and the immersion. That is added expense and imagine having to recable a long route to the immersion with screened cables. At least that is what the EMMA people have found I believe on their PWM system. It is all adding up to quite an expensive solution???
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I'd suspect it'd be more to the point to ask what proportion are actually fully compliant based on the grid impedance - the one we first hit problems with showed almost a 1V drop per kW of load, vs a 0.7V total limit under the flicker regulations (IIRC) - ie it was around 3,5 x outside the limit.
To comply for a 3kW immersion there'd need to be less than a 0.25V drop per kW of load, which I doubt applies in more than maybe 10-20% of cases close to big transformers, with chunky cabling used. I'd expect that maybe 50% or so are close enough to not really be an issue, 20-30% starting to become slightly noticeable, 10% definitely noticeable if you look for it, and 10% increasingly problematic... I think it's been masked because most solar PV adopters will also have led or CFL lights, which don't suffer flicker issues, so won't notice - but their neighbors might have halogens / filaments, and be experiencing flicker issues but not knowing why or who to complain to.
Figures are just guesstimates, but I'd think they'd be roughly in the right ball park
To comply for a 3kW immersion there'd need to be less than a 0.25V drop per kW of load, which I doubt applies in more than maybe 10-20% of cases close to big transformers, with chunky cabling used. I'd expect that maybe 50% or so are close enough to not really be an issue, 20-30% starting to become slightly noticeable, 10% definitely noticeable if you look for it, and 10% increasingly problematic... I think it's been masked because most solar PV adopters will also have led or CFL lights, which don't suffer flicker issues, so won't notice - but their neighbors might have halogens / filaments, and be experiencing flicker issues but not knowing why or who to complain to.
Figures are just guesstimates, but I'd think they'd be roughly in the right ball park
S
solar warrrior
Earlier this year an Immersun was measured against the flicker spec and failed by a margin of 4.5 on a long term (2 hrs) test and 6.7 in short term (10mins). Does your 0.25V allow for this?
My house has a 0.7V drop per kW and a different burst fire device I tried induced a lot of flicker. The few people I personally know who have tried burst fire devices of home built origin have all had flicker with 2 resulting in complaints from neighbours.
My house has a 0.7V drop per kW and a different burst fire device I tried induced a lot of flicker. The few people I personally know who have tried burst fire devices of home built origin have all had flicker with 2 resulting in complaints from neighbours.
Re: Propotional Controller Technologies
are we saying that it has this issue during the daytime only, ie when actually being sent to the immersion heater.
We have installed a few (I have 1) but havent noticed any issues (yet)
are we saying that it has this issue during the daytime only, ie when actually being sent to the immersion heater.
We have installed a few (I have 1) but havent noticed any issues (yet)
yes - well roughly speaking, IIRC the limit is 0.7V fluctuation, so 3 x 0.25V = 0.75V, which is why I said less than 0.25V per kW.
The problem with testing this is that the voltage fluctuation depends entirely on the impedance of the local grid supply, so anyone testing this in a factory environment on an industrial estate will get an entirely misleading impression of the situation when the unit is installed in domestic situations. Conversely I'd assume you must have been doing the testing in a situation with a fairly high grid impedance to get those results.
But a brief analysis of the theory would really be all it takes to conclude that there's no way units using basic burst fire technology should be controlling the power to 3kW loads in domestic situations - at least not without an analysis of the grid impedance beforehand to confirm suitability.
btw, I'm aware the flicker regulations are a little more complex than this, with the volt swing allowed varying with the frequency, but I think it's roughly true that 0.7V is the maximum allowable for a unit that has the capacity to have the burst fire operating at every other cycle, so worst case scenario needs to be used.
The published links favour one particular product whilst casting doubt on all the others. E.g. it is trying to claim that all apart from PWM ones have no Lab Conformity Certification whereas theirs does. That might be true of some/many but what evidence have they used? For instance our own product is tested and certified but is conveniently for them left off their comparison table. Were they worried that it would show up their case in favour of PWM? I am not doubting the potential of PWM for interference free operation but the products are probably expensive.
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D
danesol
When you say a MCB is/was buzzing - why does it do that as my SMA Inverter is often heard buzzing at high power generation - is this the same kind of thing ?
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