Yesterday the abstraction police descended on me: Saturday morning, unannounced, in an unmarked vehicle and brandishing paper copies of my abstraction licence. The intent was clear: to catch a criminal in the act of transgressing the terms of his licence. Is it just me who gets irritated by such tactics ?
I was irritated from the start, and that was a shame because the Natural Resources Wales (NRW) policeman who came to make the inspection was a decent fella, with a wife and child, worried about the security of his job with NRW, and with an interesting career before joining NRW. But we got off on the wrong foot with each other, largely because the circumstances of the unheralded visit made me resent being treated as a neo-criminal. Not just that: there's a long standing sore dating from when I first applied for my abstraction licence which has yet to heal. I still feel hard done by and am left nursing a grievance that NRW as an organisation fail to properly engage with clients.
With the decent fella however, toward the end of his visit, bridges had been built.
This is the third inspection I've had and each time it's someone different. No continuity which might make for a fruitful discussion with someone who knows the site from a previous time. So he was seeing it afresh. Everything needed to be explained. Queried. Photographed.
There really ought to be another way, a better way, of doing this sort of compliance visit. Most of us who have small hydro sites are people who are environmental enthusiasts. We're not going to be trashing the water courses of Wales or draining them dry from over-abstraction. And in any case, the damage possible from such minnow schemes as mine hardly makes it justifiable to do a compliance visit every year.
NRW have more important things they should be addressing: they still haven't managed to sort out a reporting system for hydro abstractors to give their annual readings on-line. It's been banded about for over three years, launched and failed twice and still hasn't seen the light of day.
It's a question of priorities: their finances are tight so they need to deploy wisely what little they have. Not happening at the moment though !
6.48 mm diameter nozzle delivering 0.91 l/s to the runner which is rotating at 1084 rpm and generating 225 watts into the grid at an overall efficiency of 47%.
Showing posts with label Paper work. Show all posts
Showing posts with label Paper work. Show all posts
Sunday, 12 August 2018
Monday, 8 August 2016
Grievances with NRW.
In the past couple of weeks I've been having a dialogue with a very nice lady at NRW. NRW stands for Natural Resources Wales. It is the body in Wales responsible for issuing and regulating licences for water abstraction.
In the UK, we call such a body a "quango", - an acronym for quasi autonomous non-governmental organisation. A quango has power to set and enforce legislation. The disconcerting thing about the power possessed by a quango is that where such legislation is later shown to contain glaring anomalies amounting to abuses which arouse protest, yet can the quango close its ears and say that such abuses are in the nature of things so must be accepted without demur.
Ordinary people like myself, coming into contact with NRW for the purpose of getting an abstraction licence, may perceive these wrongs; may perceive that an injustice is being imposed; and this creates a feeling of resentment at being unfairly treated. Yet the deafness of the organisation makes it impossible to get even a hearing, let alone redress.
The particular matter which has been the subject of my dialogue concerns the imposition of a charge for the water I abstract. Water abstracted for the generation of electricity does not attract a charge. Neither does water abstracted for domestic use, so long as the volume is less than 20 m³ per day. Yet if these two abstractions come from the same place, the way NRW has written the rules makes it compulsory to 'aggregate' the two volumes and aggregating inevitably brings the total daily volume to greater than 20 m³. Such a volume now triggers a charge; in effect: two abstractions, each on its own free yet together being made not to be free !
There have been other injustices in NRW's self written rule book which I have drawn attention to before. Let me mention two again:
1. - in this third year of operating my Powerspout I am going to generate over 4000 kWh of energy. The volume of water I have abstracted to generate this is calculated by applying a 'hydro-abstraction factor' (HAF). For my site this is 13 m³ per kWh; To have generated 4000 kWh I will thus have abstracted in excess of 52,000 m³. This is more than the limit set by my licence (49,982 m³) and yet I have generated this number of kWh's, an exceptional number for me, only because it has been an exceptionally wet year; the instantaneous flow abstracted and the daily volume abstracted, figures for both of which are also stipulated on the licence, have not been exceeded.
The injustice here is that it is inconsistent for a licence to set both a daily limit and an annual limit; there is no knowing when one applies for a licence how many wet days there will be in future years, so making prediction of an annual limit impossible. All that should matter to NRW with its concern for harm to the watercourse is that the daily limit is not exceeded. It ought to matter not at all to them if a year happens to be so wet that water is plentiful enough to allow people like myself to generate an exceptional number of kWh's.
A subsidiary point to be made about the yearly volume, if indeed there has to be one, is that it is mathematically amateurish to stipulate a figure which purports to be more precise than the accuracy possible from the method used to calculate it. My licence, instead of saying 49,982 m³ would better have said 50,000 m³, and better still from a mathematical standpoint, should have added an error allowance of, say, 10%, acknowledging the calculation method can sustain no greater accuracy than this. By allowing some measure of flexibility then at least licence holders would be saved the anxiety of overstepping their limit in occasional years.
2. - in describing the way to calculate one's HAF, NRW say that the component efficiencies of the different parts of the installation at maximum power must be used. To say this is unscientific and subtly over calculates the HAF by the effect of two linked factors:
These points of grievance are highly specific. They refer to arcane detail which is not for everyone. There is however another matter of grievance, which requires no knowledge of obscure detail, is relevant to all hydro owners and reaches to the deepest level. It has been the subject of a long running argument between NRW and the two organisations in the UK which represent owners of small hydro installations, the British Hydropower Association and the Micro-hydro Association.
It is the argument about how abstraction for electricity generation should be treated; the proposition that abstraction for the generation of electricity should not be treated as abstraction for other purposes because the one permanently removes water from a watercourse whilst the other does not; that the principles, right and proper principles as they are which guide NRW in wanting to restrict and have control of the removal of water from Wales' water courses, need to be modified when applied to abstraction for electricity.
Unfortunately for hydro owners, the response of NRW so far has been characteristic: the organisation has been unwilling to engage on the issue. In like manner I have had no real engagement on the particular grievances I have put forward. Such is the typical quango stance.
Who in an organisation like NRW are those responsible for the conduct of the organisation ?
Certainly it is not those like the lady I have been corresponding with or the two NRW field workers who paid me a visit two years ago, all of them open and approachable people but people who are necessarily constrained to work within the legislation that NRW has itself devised. What needs changing is the legislation itself.
The people at the top who sit on the board are the ones who carry the responsibility for the image the organisation conveys. As it happens, I am familiar with a few of them ! One is a micro-hydro owner who lives near to me and whose installation I have visited. With two others I share the experience of having been a senior employee of the Welsh Health Service.
Come on you board members ! - ensure NRW puts in place mechanisms for real consultation on matters of grievance concerning your legislation.
Why not have a board member who acts as an internal 'ombudsman', to whom grievances about your legislation can be addressed ? Your complaints procedure specifically excludes using the complaints route for legislative change.
In the UK, we call such a body a "quango", - an acronym for quasi autonomous non-governmental organisation. A quango has power to set and enforce legislation. The disconcerting thing about the power possessed by a quango is that where such legislation is later shown to contain glaring anomalies amounting to abuses which arouse protest, yet can the quango close its ears and say that such abuses are in the nature of things so must be accepted without demur.
Ordinary people like myself, coming into contact with NRW for the purpose of getting an abstraction licence, may perceive these wrongs; may perceive that an injustice is being imposed; and this creates a feeling of resentment at being unfairly treated. Yet the deafness of the organisation makes it impossible to get even a hearing, let alone redress.
The particular matter which has been the subject of my dialogue concerns the imposition of a charge for the water I abstract. Water abstracted for the generation of electricity does not attract a charge. Neither does water abstracted for domestic use, so long as the volume is less than 20 m³ per day. Yet if these two abstractions come from the same place, the way NRW has written the rules makes it compulsory to 'aggregate' the two volumes and aggregating inevitably brings the total daily volume to greater than 20 m³. Such a volume now triggers a charge; in effect: two abstractions, each on its own free yet together being made not to be free !
There have been other injustices in NRW's self written rule book which I have drawn attention to before. Let me mention two again:
1. - in this third year of operating my Powerspout I am going to generate over 4000 kWh of energy. The volume of water I have abstracted to generate this is calculated by applying a 'hydro-abstraction factor' (HAF). For my site this is 13 m³ per kWh; To have generated 4000 kWh I will thus have abstracted in excess of 52,000 m³. This is more than the limit set by my licence (49,982 m³) and yet I have generated this number of kWh's, an exceptional number for me, only because it has been an exceptionally wet year; the instantaneous flow abstracted and the daily volume abstracted, figures for both of which are also stipulated on the licence, have not been exceeded.
The injustice here is that it is inconsistent for a licence to set both a daily limit and an annual limit; there is no knowing when one applies for a licence how many wet days there will be in future years, so making prediction of an annual limit impossible. All that should matter to NRW with its concern for harm to the watercourse is that the daily limit is not exceeded. It ought to matter not at all to them if a year happens to be so wet that water is plentiful enough to allow people like myself to generate an exceptional number of kWh's.
A subsidiary point to be made about the yearly volume, if indeed there has to be one, is that it is mathematically amateurish to stipulate a figure which purports to be more precise than the accuracy possible from the method used to calculate it. My licence, instead of saying 49,982 m³ would better have said 50,000 m³, and better still from a mathematical standpoint, should have added an error allowance of, say, 10%, acknowledging the calculation method can sustain no greater accuracy than this. By allowing some measure of flexibility then at least licence holders would be saved the anxiety of overstepping their limit in occasional years.
2. - in describing the way to calculate one's HAF, NRW say that the component efficiencies of the different parts of the installation at maximum power must be used. To say this is unscientific and subtly over calculates the HAF by the effect of two linked factors:
- 'run of river' hydros in Wales will never operate at maximum power throughout a year
- efficiency, at least for a pelton, is not very good at maximum power
These points of grievance are highly specific. They refer to arcane detail which is not for everyone. There is however another matter of grievance, which requires no knowledge of obscure detail, is relevant to all hydro owners and reaches to the deepest level. It has been the subject of a long running argument between NRW and the two organisations in the UK which represent owners of small hydro installations, the British Hydropower Association and the Micro-hydro Association.
It is the argument about how abstraction for electricity generation should be treated; the proposition that abstraction for the generation of electricity should not be treated as abstraction for other purposes because the one permanently removes water from a watercourse whilst the other does not; that the principles, right and proper principles as they are which guide NRW in wanting to restrict and have control of the removal of water from Wales' water courses, need to be modified when applied to abstraction for electricity.
Unfortunately for hydro owners, the response of NRW so far has been characteristic: the organisation has been unwilling to engage on the issue. In like manner I have had no real engagement on the particular grievances I have put forward. Such is the typical quango stance.
Who in an organisation like NRW are those responsible for the conduct of the organisation ?
Certainly it is not those like the lady I have been corresponding with or the two NRW field workers who paid me a visit two years ago, all of them open and approachable people but people who are necessarily constrained to work within the legislation that NRW has itself devised. What needs changing is the legislation itself.
The people at the top who sit on the board are the ones who carry the responsibility for the image the organisation conveys. As it happens, I am familiar with a few of them ! One is a micro-hydro owner who lives near to me and whose installation I have visited. With two others I share the experience of having been a senior employee of the Welsh Health Service.
Come on you board members ! - ensure NRW puts in place mechanisms for real consultation on matters of grievance concerning your legislation.
Why not have a board member who acts as an internal 'ombudsman', to whom grievances about your legislation can be addressed ? Your complaints procedure specifically excludes using the complaints route for legislative change.
Tuesday, 15 March 2016
The UK "Energy Performance Certificate".
There might not seem to be any relevance on a blog devoted to a Powerspout for me to be writing about the UK Energy Performance Certificate (EPC). Yet for readers in the UK, and this entry is really for UK readers alone, there is great relevance. Not only is the matter relevant to owners of Powerspout turbines but to owners of all 'domestic scale' hydros in the UK.
To rehearse the background: an EPC is required by law whenever a property is built, sold or rented. It contains info about a property's energy use and typical energy costs, and it gives recommendations about how to reduce these. The certificate gives a property an energy efficiency rating on a scale from A (most efficient) to G (least efficient), is valid for 10 years and is issued following an energy assessment undertaken by a qualified assessor.
The origin of EPC legislation lies in the UK government's efforts to reduce carbon emissions and influence global warming: the energy we use for heating, lighting and power in our homes produces over a quarter of the UK's CO2 emissions. The certificate makes explicit this link to CO2 by including another scale which quantifies how good or bad the property is in terms of CO2 emissions for each energy efficiency rating A to G.
So you would logically conclude from all this that a property which is lucky enough to have a hydro, which is to say a zero carbon energy source working 24/7, that such a property ought to score pretty well, at least in respect of that part of the assessment which deals with electrical energy consumption.
Moreover, you could not possibly expect the benefits from a hydro to be excluded when the certificate recommends one way of improving a property's EPC is to instal a wind turbine, - a technology which produces a far inferior energy flow compared to a hydro.
But you would be wrong if you concluded and expected these things: the reality is no electric generation from a hydro is permitted to count in the domestic energy assessor's survey of the property. The contribution from a hydro contributes not a jot to the calculation of the energy performance rating of the property.
The back story behind this completely daft anomaly is convoluted. It does not bear telling in full here. I have been arguing it this past 6 months all the way to the Minister of State for Energy, the Rt Hon Andrea Leadsom MP. Her explanation in one sentence, though in the way of politicians she took several, is that assessing the contribution from a hydro is too complicated, therefore to train the energy assessors would be too expensive, and there are too few hydros to make it all worthwhile. End of matter.
So good bye fairness, logical thought, coherent reasoning, plausible argument and sensible decision taking in the legislative process ! Those of us with hydros simply have to take it on the nose that the point on the scale where the EPC places us will be lower than it ought to be, - in the process placing a lower value on the property, and in my case, dictating that I receive a lower Feed in Tariff payment for my solar generation.
As the French might say: "tant pis pour nous" (hard luck for us). Which is indeed the only way to accept it, - but accepting it does nothing to suppress the irritation which still wells up because of such idiotic legislation.
To rehearse the background: an EPC is required by law whenever a property is built, sold or rented. It contains info about a property's energy use and typical energy costs, and it gives recommendations about how to reduce these. The certificate gives a property an energy efficiency rating on a scale from A (most efficient) to G (least efficient), is valid for 10 years and is issued following an energy assessment undertaken by a qualified assessor.
The origin of EPC legislation lies in the UK government's efforts to reduce carbon emissions and influence global warming: the energy we use for heating, lighting and power in our homes produces over a quarter of the UK's CO2 emissions. The certificate makes explicit this link to CO2 by including another scale which quantifies how good or bad the property is in terms of CO2 emissions for each energy efficiency rating A to G.
So you would logically conclude from all this that a property which is lucky enough to have a hydro, which is to say a zero carbon energy source working 24/7, that such a property ought to score pretty well, at least in respect of that part of the assessment which deals with electrical energy consumption.
Moreover, you could not possibly expect the benefits from a hydro to be excluded when the certificate recommends one way of improving a property's EPC is to instal a wind turbine, - a technology which produces a far inferior energy flow compared to a hydro.
But you would be wrong if you concluded and expected these things: the reality is no electric generation from a hydro is permitted to count in the domestic energy assessor's survey of the property. The contribution from a hydro contributes not a jot to the calculation of the energy performance rating of the property.
The back story behind this completely daft anomaly is convoluted. It does not bear telling in full here. I have been arguing it this past 6 months all the way to the Minister of State for Energy, the Rt Hon Andrea Leadsom MP. Her explanation in one sentence, though in the way of politicians she took several, is that assessing the contribution from a hydro is too complicated, therefore to train the energy assessors would be too expensive, and there are too few hydros to make it all worthwhile. End of matter.
So good bye fairness, logical thought, coherent reasoning, plausible argument and sensible decision taking in the legislative process ! Those of us with hydros simply have to take it on the nose that the point on the scale where the EPC places us will be lower than it ought to be, - in the process placing a lower value on the property, and in my case, dictating that I receive a lower Feed in Tariff payment for my solar generation.
As the French might say: "tant pis pour nous" (hard luck for us). Which is indeed the only way to accept it, - but accepting it does nothing to suppress the irritation which still wells up because of such idiotic legislation.
Saturday, 21 February 2015
NRW Inspection visit
This week, Natural Resources Wales (NRW), the organisation responsible for regulating water abstraction, paid me a visit to check that I was keeping to the terms of the licence they issued.
For an organisation which has been deaf to the protestations of the UK Microhydro Association and the British Hydro Power Association that its licensing procedure is inappropriate for hydro installations, I was pleasantly surprised that the two NRW people who came were willing to listen to the arguments I wanted to put forward.
I had prepared for them coming. I wanted to get across three things:
1. calculating abstraction volumes using the efficiency of the system at maximum power is wrong headed.
2. stipulating an annual maximum volume of abstraction is meaningless if the licence specifies the maximum instantaneous flow which can be taken.
3. the wording of their licence is internally inconsistent by stipulating in one section the maximum volumes to be extracted, yet in another section giving these same volumes as being minimum volumes.
To make the point about efficiency I gave them this graph which shows how efficiency falls off toward the upper end of power output. It is the same plot as I've posted before but in a different format and with additional data points added. By making licence holders calculate their abstraction volumes at maximum power, where the efficiency is less, NRW force their clients to overstate the volume abstracted. Moreover, very few sites operate at maximum power for many weeks in a year so that forcing the use of efficiency at maximum power is unlikely to be representative of efficiency for the whole year. (edited 28 Oct 2025).
To make the point about having to adhere to an annual maximum volume, I pointed out that with the volume I've abstracted up to the end of January being 39,727 m³ and with two months still to go before the end of their "abstraction year" on March 31st, I was almost certainly going to breach the annual limit set at 49,982 m³, despite having kept within the limit of instantaneous flow set at 3 litres per sec.
Will anything come of it all ? - I'm not holding my breath, but on the day of the visit at least, it was nice to be reminded that there are, working within this bureaucratic quango, intelligent, approachable, rational, human beings.
For an organisation which has been deaf to the protestations of the UK Microhydro Association and the British Hydro Power Association that its licensing procedure is inappropriate for hydro installations, I was pleasantly surprised that the two NRW people who came were willing to listen to the arguments I wanted to put forward.
I had prepared for them coming. I wanted to get across three things:
1. calculating abstraction volumes using the efficiency of the system at maximum power is wrong headed.
2. stipulating an annual maximum volume of abstraction is meaningless if the licence specifies the maximum instantaneous flow which can be taken.
3. the wording of their licence is internally inconsistent by stipulating in one section the maximum volumes to be extracted, yet in another section giving these same volumes as being minimum volumes.
To make the point about efficiency I gave them this graph which shows how efficiency falls off toward the upper end of power output. It is the same plot as I've posted before but in a different format and with additional data points added. By making licence holders calculate their abstraction volumes at maximum power, where the efficiency is less, NRW force their clients to overstate the volume abstracted. Moreover, very few sites operate at maximum power for many weeks in a year so that forcing the use of efficiency at maximum power is unlikely to be representative of efficiency for the whole year. (edited 28 Oct 2025).
To make the point about having to adhere to an annual maximum volume, I pointed out that with the volume I've abstracted up to the end of January being 39,727 m³ and with two months still to go before the end of their "abstraction year" on March 31st, I was almost certainly going to breach the annual limit set at 49,982 m³, despite having kept within the limit of instantaneous flow set at 3 litres per sec.
Will anything come of it all ? - I'm not holding my breath, but on the day of the visit at least, it was nice to be reminded that there are, working within this bureaucratic quango, intelligent, approachable, rational, human beings.
Saturday, 29 November 2014
More paper work !
At the end of each month I need to remember to keep my records up-to-date.
This November has been a bonanza month for generation, especially considering it was only from Nov 5th that there was sufficient flow to generate anything at all. By the end of the month, 393.7 kWh will have been clocked up, and the capacity factor for the month will be a very presentable 0.73.
I need to remember because a return stating the volume of water I've abstracted has to be sent to Natural Resources Wales (NRW). NRW like the year to be broken down into individual months, and you have to give the volume abstracted in each month. The return has to be sent in within 28 days after 31st March but fortunately they post the form to you as a reminder.
For my scheme, to generate each kWh requires 13 m³ of water; this is a figure the NRW call the Hydro Abstraction Factor and they tell you how to calculate it for your scheme. The inputs to the calculation, which will vary from site to site, are the 'water-to-wire' efficiency and the head of the scheme.
Here is the spreadsheet I keep of monthly abstraction so everything is to hand at the end of March to complete the annual return:
This November has been a bonanza month for generation, especially considering it was only from Nov 5th that there was sufficient flow to generate anything at all. By the end of the month, 393.7 kWh will have been clocked up, and the capacity factor for the month will be a very presentable 0.73.
I need to remember because a return stating the volume of water I've abstracted has to be sent to Natural Resources Wales (NRW). NRW like the year to be broken down into individual months, and you have to give the volume abstracted in each month. The return has to be sent in within 28 days after 31st March but fortunately they post the form to you as a reminder.
For my scheme, to generate each kWh requires 13 m³ of water; this is a figure the NRW call the Hydro Abstraction Factor and they tell you how to calculate it for your scheme. The inputs to the calculation, which will vary from site to site, are the 'water-to-wire' efficiency and the head of the scheme.
Here is the spreadsheet I keep of monthly abstraction so everything is to hand at the end of March to complete the annual return:
So that was one bit of paperwork I had to remember to do. The other was applying for payment for the kWh's generated in the past 3 months. Since the turbine doesn't operate for most of that quarter, for lack of water, a November claim is the lowest of the year: just £71 on this occasion.
Claiming feed-in-tariff is a much more straightforward business. I opted for a contract with Scottish and Southern Electricity (SSE) simply because they're the company we purchase power from and it seemed to make sense to stick with them. Submitting a generation-meter reading on-line is simplicity itself at the SSE webpage. You immediately get email confirmation of your claim being processed and payment comes through direct to your bank account, - somewhat unusually on this occasion, within 48 hrs.
Co-incidently, I had a letter from SSE today telling me they're in the process of updating their FIT payment system. When completed, I'll be assigned a new date in each quarter on which to submit my FIT claim and more detail will be provided about how it is calculated. Additionally, their man who comes to read the meter will, in future, read both consumption and generation meters at the same visit.
So the take-home message is: in the UK at least, there is a fair amount of bureaucracy involved in operating even a small hydro installation, but like a tax return, so long as you keep on top of all the figures and the deadlines, it isn't burdensome.
Friday, 14 November 2014
TIC, DNC, Abstraction and all that stuff.
For the first time, I now have the Powerspout operating at 'design flow', - at least it's the first time I've had any certainty the flow being delivered is the design flow: 3 lps. So for the first time too, I have reliable figures for those two parameters so loved by OFGEM: Total Installed Capacity (TIC) and Declared Net Capacity (DNC). OFGEM is the UK body giving accreditation for an installation to receive payment for the electricity it generates.
Just to set the record straight: DNC is TIC "less any electricity consumed by the generator". So for a Powerspout the power taken by the inverter (see last post) has to be deducted from TIC to get DNC. Both of these figures need to be specified at the "highest capacity at which the generating station could be operated for a sustained period ... without causing damage to the generating station". I took that to mean at 'design flow'.
I may have taken it to be at design flow but in fact a Smart Drive alternator can put out in excess of 1kW for a sustained period and without being damaged, so there is nothing actually to stop me from delivering a flow in excess of 3 lps, when it's available, and getting more power. That would've meant giving OFGEM a higher TIC and higher DNC. So where do you draw a line in the sand ?
I opted to give values for TIC and DNC based on 3 lps because my abstraction licence limits me to that flow. Which begs the question "why didn't you ask for a higher abstraction volume?" And the answer to that is another line in the sand: it seemed from the flow duration plot for my site to be the optimum peak flow when the pattern of flow over a full year is taken into consideration.
I relate all this to make the point that filling in all the forms to make an installation 'legal' is a headache. Moreover what you put on one form, the Abstraction application, has a bearing on what you put on your OFGEM form to get accredited for Feed in Tariff payments.
To get back to real figures, below is the actual return I submitted to OFGEM last year for my FIT accreditation...
... and as you can see, I put 0.8 for TIC and 0.75 for DNC. These were, at the time, the best estimates I could come up with. They were supported, as the extract above requires, by independent confirmation from Michael Lawley, the manufacturer of Powerspouts, who used the calculator tool on the Powerspout website to confirm my expected output.
But the thing is: it's very difficult to get the accuracy of the inputs to that calculator tool to be spot on; now I have real data available, I find the true TIC and DNC aren't what I submitted. The DNC turns out to be 0.92kW and the TIC 1.1 kW.*
Do these small differences matter ?: no ! - no one at OFGEM is going to be any the wiser that my submission figures were 5% out. But the saga does draw attention to the fact that in completing these forms, what you enter on one, the abstraction application, has a bearing on what you should enter on the other: the FIT application. And deciding where 'the lines in the sand are to be drawn', I found to be a hard call.
Finally, if you're wondering what OFGEM's definition of DNC is in full, as hyperlinked in the above extract, this is it:
Confused ? - so was I, - and to a large extent, I still am. The forms are, truly, a headache.
* figures amended April 2020 with knowledge gained over the 6 years since original post was written.
Just to set the record straight: DNC is TIC "less any electricity consumed by the generator". So for a Powerspout the power taken by the inverter (see last post) has to be deducted from TIC to get DNC. Both of these figures need to be specified at the "highest capacity at which the generating station could be operated for a sustained period ... without causing damage to the generating station". I took that to mean at 'design flow'.
I may have taken it to be at design flow but in fact a Smart Drive alternator can put out in excess of 1kW for a sustained period and without being damaged, so there is nothing actually to stop me from delivering a flow in excess of 3 lps, when it's available, and getting more power. That would've meant giving OFGEM a higher TIC and higher DNC. So where do you draw a line in the sand ?
I opted to give values for TIC and DNC based on 3 lps because my abstraction licence limits me to that flow. Which begs the question "why didn't you ask for a higher abstraction volume?" And the answer to that is another line in the sand: it seemed from the flow duration plot for my site to be the optimum peak flow when the pattern of flow over a full year is taken into consideration.
I relate all this to make the point that filling in all the forms to make an installation 'legal' is a headache. Moreover what you put on one form, the Abstraction application, has a bearing on what you put on your OFGEM form to get accredited for Feed in Tariff payments.
To get back to real figures, below is the actual return I submitted to OFGEM last year for my FIT accreditation...
... and as you can see, I put 0.8 for TIC and 0.75 for DNC. These were, at the time, the best estimates I could come up with. They were supported, as the extract above requires, by independent confirmation from Michael Lawley, the manufacturer of Powerspouts, who used the calculator tool on the Powerspout website to confirm my expected output.
But the thing is: it's very difficult to get the accuracy of the inputs to that calculator tool to be spot on; now I have real data available, I find the true TIC and DNC aren't what I submitted. The DNC turns out to be 0.92kW and the TIC 1.1 kW.*
Do these small differences matter ?: no ! - no one at OFGEM is going to be any the wiser that my submission figures were 5% out. But the saga does draw attention to the fact that in completing these forms, what you enter on one, the abstraction application, has a bearing on what you should enter on the other: the FIT application. And deciding where 'the lines in the sand are to be drawn', I found to be a hard call.
Finally, if you're wondering what OFGEM's definition of DNC is in full, as hyperlinked in the above extract, this is it:
* figures amended April 2020 with knowledge gained over the 6 years since original post was written.
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