Listen to Paula talking to Winifred Robinson on Radio 4’s You & yours about the report and the issues of standby power, here

On Tuesday 26th June, ‘Powering the Nation’, the latest report I have written on behalf of the Energy Saving Trust, Defra and DECC was launched.  The publication is a summary of a much longer report that, in turn, is the outcome of a three year project to get to the heart of understanding the electricity using habits of the typical English, owner-occupier household.

The study has been ground-breaking, nothing of its ambition or depth has been attempted before in the UK.  Indeed, on a global scale, similar studies have only been carried out in Sweden and France.

The study looked at 251 homes in total.  Twenty six, or 10%, of them were studied for an entire year, whilst the other 225 were monitored for a month on a rolling basis.  Their usage then adjusted for seasonality of use as displayed by the annual householders.  The householders were picked to represent a good spread of socio-demographic types, but one limitation was that they were all, by necessity, owner occupiers.  It proved too problematic to recruit private and social tenants.

The results and insights the study has unearthed are both fascinating and intriguing in equal measure.  Although the study’s householders were, on average, more likely to be careful about saving energy in the home than the national average (86% versus 75%), the average electricity usage was 10% higher than the nationally accepted average (3300 kWh/yr.).

Stand-by power, typically quoted as about 8% of electricity bills, came out at between nine and 16% of total consumption.  Costing our study households between £50 and £86 per year, simply to keep gadgets on whilst not doing anything useful

The other shocking insight is how inefficient it seems to be to live alone.  Hard though it may be to believe, single occupancy, non-pensioner households use more electricity powering their washing machines than families do.  They spend as much on cooking as two people households and nearly as much on using the dishwasher. They also light their homes more than families.

If we own a tumble drier, we tend to use them four out of every five times we do a wash, much higher than the previously modelled average of 60% of the time.  Indicating that people potentially are not making use of the outside space they may have available to them for drying clothes, and costing them a fortune for their laundry, over £80 instead of just £26 if people just own a washing machine.

We did find a huge variation in usage and ownership levels however, both within similar dwellings and household make-up, and across the board.  One of the most startling examples of excessive use was the household who used their washing machine 1200 times in one year, when the typical average was around 300 washes.

These are a few tasters of the fascinating insights uncovered by this study, to find out more:

Click here to get a link to the summary report I have authored on behalf of  EST, DECC and Defra

Click here to get to the full report, (print out warning:600 pages long)

Click here to find out more about the database containing all the data and diary entries of the study which will be available for interrogation soon.

If you would like to talk to me about the findings of the summary report, please contact me here.


I upgraded my old dilapidated combination boiler about 4 years ago for an ultra efficient condensing variety.  And, fair play, it has worked very well ever since with no issues.  Indeed, at a recent efficiency check carried out by my plumber, it hasn’t lost any of its efficiency in the intervening years.  But, there has always been one aspect of a combination boiler that has bothered me – and that is the length of time it takes to warm up water for that first shower of the day, or when you are washing up and have not used the hot water tap for a while.

I haven’t quantified exactly how much water I have to waste whilst waiting the the shower to get hot, but it is at least a minutes worth before the water has sufficiently warmed for me to get in it.  Similarly with washing up, the waste of clean water down the sink whilst waiting for it to get warm enough to wash dishes in is criminal, and as I’m also on a water meter, it’s a waste of money too.

At one stage I was collecting the shower water in a bucket and using it to water the indoor plants, but there is only so much of that you can do.  So I’ve often pondered that there should be a solution to this dilemma – and one not involving going back to a boiler with hot water tank, which can be equally wasteful of gas if you do not use the hot water that it regularly heats up in the hot water tank whether you need it or not.

Anyway, my wonderful plumber John, of Aqueous Plumbing (a south London based company if anyone is in need of a good plumber), has alerted me to a potential solution.  It’s called a ‘Combisave’ and it claims to reduce the water flow at those crucial times when the water is heating up from a standing start – this, according to their website, saves not only time in getting your hot water quicker, but both water and gas too.

The claims on the website, for a monetary saving for a family of 4 in a typical household, are quite ambitious.  Apparently, they claim you can save:

 – £55 on your hot water bill, but that could be as much as over £100

– if on a water meter, then the savings here are quoted at  £180 per year.

I have a few issues with these figures, as they seem to be based on each one of 4 family members using a hot water tap and/or shower 7 times each a day (28 uses of hot water per day in total – more than 1 use an hour!) – and each time having to wait a minute for the water to heat up!  My big issues with these assumptions are, if as in most normal households, especially on weekday mornings, the showers are taken in quick succession, then the water will not take up to a minute to heat up for all 4 showers, only the first one, after that the hot water is instantaneous as it is still warm in the pipes.  So their claim that a 4 person household can save 55,000 litres of water a year seems very optimistic to say the least.

But if it saves just the first 6 litres per day of the family’s showers, then that’s an annual saving of around 2200 litres of shower water.  Then you can add maybe another 6 litres waiting for the water to warm up when washing up in the evening (in non-dishwasher households), so that saving could presumably be doubled to about 4400 litres per year.

This could save you about £14.50 per year on a water meter (using 0.3pence/litre – their figure).

I’m not clear how to calculate the gas saving in this situation, but if we take their optimistic figure for a gas saving, and divide that by 12 (this is the reduction in the water saving given what they have calculated versus what I estimate it could be, ie 55,000/4400 litres = 12 times smaller) that gives a yearly saving of 1650 kWh/12 = 137.5 kWh.  Typical price of gas is currently around 4.5pence.  Hence saving in gas could be £5.50.  Giving a yearly combined saving in gas and water bills of about £20.  This might be a conservative low end saving, but I think its more realistic than their £200 – 300 saving figure

So, given a Combisave costs around £90, and then you will have fitting costs too ( it has to be fitted by a qualified plumber) of around £50 upwards, then we are looking at a payback, if you are on a water meter, of around  7 years.  I’m not sure how long a ‘Combisave’ is made to run for, but if it’s a ‘fit it and forget it’ device, and the lifetime is longer than 7 years, you will eventually make your money back – but most importantly, in my view, you will be doing your bit to save water in these drought-ridden times.

I’ve been monitoring my daily water and gas usage over the last week, and will be getting one of these fitted by John my plumber soon.  So watch this space for a review of how much it is actually saving me.

Want to read the results of my first month of use? Click here:


Being a bit of a geek, I thought I’d ‘do the math’ on my PV system’s generation, total household usage and the amount of my own electricity I’ve consumed over the last 7 months.  I chose 7 months, rather than the total 10 months of PV generation, as it was 7 months ago that my electricity meter was swapped for a new backstop meter; before then, because of the backwards running meter issue, it was impossible to tell how much of my own power I was actually using.

So, what are the scores on the doors?  Since the end of September 2011, I have clocked up approximately 1000 kWh on my new consumption meter.  This being the amount I have needed to pull from the grid.  However, because of my nifty Wattson meter, I have a record – month by month and day by day – of my actual total electricity consumption over that time.  A brief calculation on my usage data from October until the end of April shows I have actually consumed a total of 1250 kWh.

Hence by the powers of subtraction I can say that, from the period from October to end April, I have used 250 kWh of my own generated power.  That doesn’t seem a huge amount really! Then I looked at my total generation over the same period, and it totaled a rather meagre 350 kWh.  So, this shows that I have used just over 70% of my total generated power from October to the end of April, higher than the average, assumed, 50%.  And I can also say that my system has provided me with around 20% of my total electricity need over the same scale. 

I will perform the same calculation again at the end of the summer, it’s my theory that my percentage of used PV power will drop considerably as I’m expecting, if we do actually see some sun this year, that my generated power will start to really pick up in the next 3 months, but I will not be able to make optimum use of it as there is only so many laundry washes you can put on when the sun is shining!  The unfortunate truth is your peak demand for electrcity is in the evening, when you need light and are cooking, hence you still need to top up on grid electricity, even if you have generated more than enough power to meet your daily needs during the day.  I’m more than ever convinced of the urgent need for a small – in both size and capacity (only needs to be a few kilowatts), cheap, battery storage solution for domestic PV systems.  Only then will we really begin to make headway in reducing peak load issues.

So, what else have I learnt lately?  One thing is to check your system after a power cut!  A while ago, when the solar flares were threatening to hit earth and ‘destroy human life as we know it’ but then didn’t, we in south London suffered a power cut in the middle of the night.  It was all back to normal by morning, but, a couple of days later when I was absentmindedly checking my generation on a sunny day, I realised that I wasn’t generating anything?!  Cue mild panic and worry that maybe the ‘deadly’ solar flares had killed my system, and worried calls to my PV installer.  It turns out that it is not necessarily a power cut that can turn your system off, but if there is a power surge before the black out then that can certainly trip the system and it doesn’t automatically reset itself when the power is restored.  So the lesson to learn is regularly check your system, especially if you haven’t got a display unit that easily shows you what you are generating at any given time.  It could be easy to lose days of good generating potential without even realising it.

Related blog posts:

Lessons I have learnt Part 1

Electricity meter going backwards after PV installation?

Unintended consequences of PV systems and meters running backwards


The visits to my blog post on backwards running electricity meters are still increasing, and the comments, both publicly and privately to me, continue to flood in.  I have now had over 1,500 visits in the last few months alone.  And people say this is not a big issue?!?  I figure the exponential leap in interest in this issue coincides perfectly with the ‘dash for PV’ that happened since the government’s announcement of the cutting of the FiT rate back in the autumn, and it’s been since Feb/March when the weather has got much more clement (and so they are beginning to generate more than they use) that this new breed of PV micro-generators are experiencing the backwards running of their electricity meters for the first time and are befuddled by it; hopping on Google to find out more and then hitting my site.

What I am noticing recently is a new worrying trend, worrying that is if you think that all these micro-generating households should be reducing their use of ‘dirty’ grid based electricity and contributing to a cleaner electricity supply.

I have had several email exchanges with people who are worried that their electricity meters are going backwards to such a degree that they are in negative amounts on their usage meters  They, for their own reasons, don’t particularly want to inform their energy supplier of the fact, but realise their need to make it look as if they are at least using some electricity so their supplier doesn’t get suspicious and suss out what is going on.

So what is their solution to this?  They are using their immersion heaters to heat up hot water, as well as using electric heating (when they have gas central heating systems) to heat their homes – when the sun isn’t shining.  Now we all know that using electricity to heat both space and water is a pretty uneconomical thing to do if you have a gas system installed – carbon wise as well as monetarily – but for these householders the monetary side isn’t relevant as they are simply trying to get back into ‘positive’ numbers, even just slightly, on their usage meter.

But think about the carbon impact of this.  The whole idea of people generating their own ‘clean’ electricity is to reduce their carbon footprint and be part of the green revolution (although, of course, some people are only interested in the revenue side of this scheme), but for people with perfectly good, and much less carbon intensive, gas heating and hot water systems in their homes, to start using grid electricity unnecessarily to heat water and space, is concerning from a carbon point of view.

I accept some people will argue I am being idealistic about this, and that they have ‘generated’ a certain amount of ‘free’ electricity, and so why shouldn’t they ‘use’ all of it, using the grid as a sort of ‘storage battery’ for their electricity which they can then use when the sun isn’t shining, but from a peak load management (domestically this is between 5-9 pm) point of view as well as a carbon reduction issue in the future, this type of behaviour is not helping. 

Related blog posts:

Being a PV generator: Lessons I have learnt Part 1

Being a PV generator: Lesson learnt Part 2

PV systems and meters running backwards: need for clear guidance





FREE BRIEFING: due to overwhelming interest in the issue of ‘electricity usage meters going backwards after PV installation’ we have produced a briefing note on the topic. Click here to contact us to request your FREE copy

So, I’m now over 6 months into my ownership of PV panels and the vagaries of the seasons, and their effect on electricity production, are becoming clear in relation to the issues with renewable generation.

The first 3 months of production, roughly July through to September, produced approximately 311 KWh of electricity (and an income of about £140), the second 3 months, October through December, produced a rather less impressive 129 KWh (and an income of about £57).  So for 6 months the total generation and income for my 1.67KW peak system is 440 KWH and about £200.  If this is projected for a full 12 months it will mean a total production of approx 1000 KWh and a yearly yield of around £400-500.  So payback on an £8K system, based on those generation rates will be nearly 20 years, and that is with the 43.3pence tariff.  I haven’t included my reduction on my electricity bill here as I had the issue of my backward running meter in place for the first 2 months of PV production (the highest 2 months of production so far) so it’s hard to tell the true reduction in my use of grid electricity through those months. However, my typical annual usage is low anyway (about 1700 KWh historically, compared with a stated national average of 3300 KWh per UK household) so I cannot expect a huge reduction in my yearly bills, £100 max I predict.

Talking about electricity use meters going backwards, the number of searches that have brought people to my website using a variation on this theme is now in the hundreds, and the blog post has been read 230 times, and I regularly get 5-6 hits a day on the topic.  So this is a widespread problem.  With 50,000 plus installations in already, and no-one systematically tackling the issue, energy suppliers are going to have a merry old time trying to sort out very unusually low electricity bills in the summer months, and I wonder how vigorously they will try to claw back that missing historical electricity usage that has been lost to the backward running meters?

Looking at other seasonal factors, the snow we have had recently have very much affected generation, on the days of snow fall we have produced exactly zero KW of electricity, it’s the first time absolutely no generation has occurred, as even on the cloudiest, most overcast day we have still generated something.  I had hoped that the panels’ surfaces were sufficiently slippery and on enough of an angle that would mean the snow would not settle too much and hence would self clean, but that obviously hasn’t been the case.  So you can imagine that in a heavy and persistent snowfall all PV generation could come to a standstill.  An issue I wonder if the powers that be have taken into account in their forward projections.

So, I await with interest the next 6 months.  We are now into a six month period with increasing daylight hours.  I have even noticed a difference from January to February in terms of how early generation starts in the mornings.  Given that our summer from July onwards was a bit of a wash out, I’m hopeful that the second 6 months will be more productive than the first., but only time will tell. Watch this space.

Related blog posts:

Being a PV generator: Lessons I have learnt Part 1

Being a PV generator: Lesson learnt Part 2

PV systems and meters running backwards: need for clear guidance



Last Autumn I finally got around to looking into getting external Solid Wall Insulation (SWI) on the gable end of my Edwardian semi.  The memory of freezing in blankets, hats and gloves in last year’s big chill with the heating full on, but only getting to about 15-16˚C max, was fresh and raw in my mind.   I had also recently met a lovely lady from Sto – the solid wall insulation product experts – who seemed confident that doing just the one, side wall would be workable and make a huge difference to our thermal comfort and heating bills.

Apart from being slightly less frostbitten in my home this winter, my other motivation was to test out the mechanism by which SWI was installed.  I want to experience the process, from the initial interactions with the council through to how the installation process impacted on the householder, as it is a much more involved process than, say, installing Cavity Wall insulation.  I also promote it widely to owners of solid walled homes in my work, but don’t have direct experience of it and how it performs, which is a gap in my ‘toolkit’ that needs filling.

Mass roll out of external SWI is an essential element of the Green Deal – actually getting to these 6-8 million ‘Hard-to-Treat’ homes and making a marked difference to their efficiency and fuel bills is at its core and vital to its sucess.  So far installation numbers for SWI are in the thousands per year, mainly because it is an expensive and, in the eyes of householders, a complicated product to install.   This installation rate needs to increase by a factor of about 10 quickly, as in this decade, if the Green Deal is going to deliver the carbon savings it is hoping for in the timescale required.

Lorraine from Sto, and Jason from P3 Projection coatings, who would be doing the install, visited for a technical survey and measure up in November and from the practical side of things, it was going to be challenging (mainly due to a narrow side alleyway which made the scaffolding tricky) but doable.  Hooray, first hurdle overcome. Tick that box.   They went away to work up a cost for the project and my task was to contact the council to ensure there were no issues with installing SWI on my house.

This is where the complications start.  Just before Christmas I received a response to my initial enquiry to Lambeth Planning Dept asking whether there would be any issues to me putting SWI on my gable wall.  I’m not in a conservation area and neither is my 1905 Edwardian semi of any listed status; so, hopefully no issues there.  However, the Planning Dept at Lambeth have come up with an alternative ‘issue’, one that is rather difficult to take seriously.

Basically the council has decreed (unofficially of course, I’d need to apply officially to get this officially ‘in writing’) that because the external SWI would be over around 100mm in depth (that’s just 10cms folks, on just one wall of the house) it does not come under ‘permitted development rights’ and hence is not permitted without first going through the planning permission process.  Planning permission that cost £100s, if not over a thousand pounds, and takes up to 12 weeks, with no guarantee of success.   Apparently any addition that is over 100mm is seen as an ‘Expansion of a dwelling’ – now this is faintly ridiculous; how can a cladding which sole purpose is to increase the thermal efficiency of an old leaky home, be considered as an ‘expansion’ of a home in any sensible way?

I reproduce the text from the council:

“My colleagues in planning are of the view that the application of an insulating material and a render skim would normally result in the ‘enlargement’ of the property. The extent of enlargement would be dependent on the thickness of the insulating material and the render. We have had very few proposals for the external rendering of properties and from my limited understanding the render thickness normally ranges from 100mm upward.

The national planning regulations allow for single family dwelling houses to have ‘permitted development rights’ which allow some work to be undertaken without the need for planning approval. The regulations make reference to the ‘enlargement’ of a property and present circumstances where enlargement would be ‘permitted development’ and other circumstances where it would not. I have reproduced the text below for your consideration:”

Naturally, I will be contesting this rather ‘jobsworthy’ view and also attempting to get responses from other councils on what their views on this issue are.  Will SWI become another ‘postcode lottery’ I wonder?  If this is a widespread view amongst local councils, it could have a devastating effect on the ambitions of the Green Deal to finally crack the nut  that would help ‘Hard to Treat’ homes come up to a decent standard in terms of thermal efficiency.

The BBC is potentially interested in this story, so if anyone reading this has had a similar response to from their council on this issue, please get in touch with me.


Yesterday I was asked by the BBC News online to comment on an innovative piece of research by the FMCG giant Unilever. Unilever have recently launched their Sustainable Living initiative and as part of they have been investigating people’s most intimate habits –  that is ‘what exactly goes on in the bathroom’??

They rightly point out that self declaration on bathing habits, and even diaries, can be inaccurate for a number of reasons – the fact that people want to say the right thing and look good in the eyes of the investigator, or simply that people are pretty bad at estimating time when an action is totally habitual and unconscious.

So those cunning scientists at Unilever came up with a technological solution.  They attached shower monitors onto the hot water pipes in 100 UK family homes, and monitored exactly what went on in the shower cubicle each morning.

The results are startling and a little depressing.  Although 4 minute showers are encouraged as an optimal time in which to get clean, but not to use too much hot water; the families in the study were routinely using double that!  And, less surprisingly perhaps, young boys and teenage girls were the worst offenders in terms of time spent under the shower rose.

There are a few things about the Unilever findings that I do not agree with though.  They talk rightly about the fact that power showers can use as much water as a deep bath if too much time is spent under them, but they then quote some enormous figures in terms of how much money this might cost the average family of 4 to run each year.

For a ‘standard shower’ (although exactly what that is is not clearly defined) – they say it could cost an average family of 4 around £416 per year just to shower.  Now this seems rather alarmist,  if we take a standard ‘electric shower’ (46% of installed showers) as the example, then the average electricity bill in the UK currently is around £550.  So they are claiming that the shower alone could be accounting for 80% of the bill.  But if they are refering to a standard gas heated mixer shower (38% of installed showers), the number gets more far fetched – as the average gas bill nowadays is around £850 – so showering would account for half of that total.  Given that a rule of thumb is that heating water is responsible about 30% of our heating bill (~£275), and that includes all washing and use of taps etc – then that number seems far too high for an ‘average’.

There there is the £900+ for a power shower.  This is realy taking an extreme example and presenting it in a way that makes it sound like a possiblity for the average home-owner.  Power showers were only 16% of the installed shower market in 2007, so they are by far the minority technology.  They are seen to have a pump rate of between 10-20 litres per minute.  To arive at such a high cost, Unilever much be taking the scenario of a very high flow rate and each of the family having 8 minute showers each day.

Also the average use of water per person per day in the UK is 150 litres.  This is unnecessarily high and we have a target to reduce that to 130 litres over the coming years, but if we take the extreme example that Unilever is using, each family member uses almost that on showering (17 litres x 8 minutes =  136 litres) alone.

It could be that Unilever are somehow factoring in the water costs too, but if so it would be interesting to see how this has been done.  As you can only make a saving, or spend more, on showering if you are on a water meter.  There are currently approximately 30% of homes on meters, and the costs of water vary enormously around the country; hence I would question the validity of adding a water cost to this ‘average’ price of showering.

So, I salute Unilever for this ground-breaking study and alerting people to the issue of longer showers not necessarily being better – environmentally or cheaper to run – than a bath; but I do mark them down for being too extreme with their figures.  We need to educate and bring people along with us on behaviour change issues; we should not try to shock people with unrealistic, atypical worst case scenarios presented as ‘average’.



Last week I had the pleasure of helping launch the Elephant in the Living Room – a 5-year update on the earlier report Rise of the Machines that I wrote on behalf of the Energy Saving Trust.  It was particularly enjoyable as I got to share a stage with someone I very much admire – Wayne Hemingway – who has done so much work in the two spheres close to my heart, namely all things vintage and sustainabllty.

To summarise the findings of the report:  Elephant has taken a look back over the last five agenda-changing years in the energy efficiency sector to report on the progress.   It then looks forward to 2020 to determine the size of the challenge ahead, and examines the contribution that domestic power use will make to hitting our short term emission reduction targets.

The first thing to highlight is the good progress made.  The combined efforts of the energy suppliers through CERT; the great breakthroughs made by the CE and ICT manufacturers to make their products more efficient; and action by both national government and the EU has ensured that the position we find ourselves in in 2011 is more positive than we were forecasting in 2006.

Indeed, two of the ‘big six’ domestic product groups are seeing, for the first time in 40+ years, a reduction in their overall demand profiles and this is set to continue to 2020.  These two – lighting and refrigeration – have traditionally been the biggest hitters in terms of power consumption, so this is very positive news.  The next two – washing and cooking products – are plateauing in terms of demand, and current 2020 projections see either flat-lining or a slight increase in consumption.

The final two, consumer electronics and home computing, are still seeing rises in energy demand, albeit not as dramatic as earlier forecasts were suggesting.  In fact, consumer electronics overtook lighting to become the single biggest electricity using product group in the mid-2000s.  These rises will continue, 5% and 7% for CE and ICT respectively up to 2020.

As far as the contribution to our 34% reduction in emissions is concerned.  We, obviously, have to take into consideration both the total electricity consumed, coupled with the possible carbon intensity of electricity in 2020.  Given two potential carbon intensities of electricity – either similar to current intensity or where the UK meets its low carbon energy targets – the report estimates that the contribution of domestic electricals to helping us reach our target misses it either by a few percentage points or up to 14% depending on the carbon factor.

To conclude, I was asked, if this were an ‘end of term’ report for the domestic products sector what grade would I give it.  After some thought, I decided on a B minus.  We have made good progress in the intervening years, but an extra push is needed within the next 8 years to ensure the this sector fully plays its part in reducing total energy demand and ultimately carbon emissions.


FREE BRIEFING: due to overwhelming interest in the issue of ‘electricity usage meters going backwards after PV installation’ we have produced a briefing note on the topic. Click here to contact us to request your FREE copy.

It’s now been over 2 months since my solar panels were installed and commissioned.  And I have just filled in my first generation form to receive my first FIT payment.  I have also learnt a few new things about PV generation that I thought it would be useful to pass on to others.

Lesson #1 – your electricity usage meter should not go backwards!

In an earlier blog I wrote excitedly about the thrill of my electricity meter going backwards. Well, my first big lesson is that it should not be running backwards!  Basically, as I am quite a frugal electricity user anyway my generating capacity over the summer (I use the term lightly) months has slightly exceeded my usage.  And, because I have an ancient, analogue electricity meter recording my general usage, I was finding that it was running backwards and actually giving me a negative reading.  This put me in the unusual position of giving my energy supplier a negative reading for my quarterly bill update – a case of them paying me for my (non)usage.

Therein lies a problem with old analogue meters, they do not simply stop moving when you add a micro-generator to the circuit that is supplying you with all the electricity you require, they will turn backwards, recording the total amount of generated power you are producing – regardless of whether you use it, or whether it goes back to the grid.

I’ve informed my electricity supplier of this and they are now arranging for me to get a new digital meter; which will simply stop moving forward when I am using my own generating power, but will never turn backwards.  These are called ‘back stop’ usage meters apparently

I did ask whether it would be possible to bypass the installation of another ‘dumb’ meter and go straight for a smart meter, given that my meter will have to be changed again within the next 8 years to comply with the timetable for all homes to have smart metering by 2019, but unfortunately, as I’m not with British Gas, this is not an option currently – which seems a wasted opportunity to me.

So my earlier excitement of the possibility of receiving a 6pence electricity bill was short-lived I’m afraid.  I’m not sure how we will work out exactly how much electricity I have actually taken from the grid in the last 2 months – as opposed to my self-generated usage, but I’m guessing it is going to be a lot higher than a few pennies worth.

Related blog posts:

Being a PV generator: Lesson learnt Part 2

PV systems and meters running backwards: need for clear guidance




It has been an exciting week this week, as I have now officially become a micro-generator and as such am playing my part in supplying the grid with clean, green electricity – albeit a rather modest amount!  My small, but perfectly formed, 1.68KWp PV system was commissioned last Friday and has been hard at work generating all week.

Here are some of the figures from my first week in the generation business:

Total KWhs generated: Approx 40

Typical daily KWh generated: 5  to 6

Hours of generation 8am – 8pm

Peak generation so far: 1.6 KWh

Total FIT income: Approx £18

What has surprised me the most is that, even first thing in the morning (8ish) when the sun is not directly on my panels, I am still generating enough to easily cover my ‘base load’ electricity.  Also, even when it is totally overcast and pouring with rain, I am still generating enough to cover my typical usage.

A slightly irritating aspect is my average daily use of electricity is 5KWh (this hardly varies throughout the year); so if there was a viable, and affordable, battery technology that could store my excess generation through the day, in summer I would be totally self-reliant on my own power.  And hence for 6 months of the year my electricity bills would be zero.

One really useful gadget is the Wattson Solar RTD which was given to me as part of the package by my installer Joju Solar.  This nifty device displays lots of different data.  You can see what you are generating in real time; what you are using and then a net consumption value.  I tend to keep it on the net consumption as It great when it displays a negative value – telling me my generation is outweighing my consumption.

So, so far so good.  The system seems to be working optimally, and even with our changeable weather this week it has delivered a reasonable amount of power.  The Wattson allows a download of all the data onto computer, so I will be able to create graphs of generation and usage to share with fellow data nerds in future.  Watch this space.