August 2011 archive

Aug 30 2011

Photovoltaic solar power – one year on

This time last year we had a photovoltaic solar power system installed, a few years after we had a thermal solar system installed. This post is an update on how we’ve got on with the photovoltaic solar system. This is facilitated by my weekly collection of electric, solar and gas meter readings – I suspect this data collection is a bit of a minority sport. A couple of months ago the company that the installed the system did offer me a fancy monitoring system… which cost about £1500!

As my earlier blog post highlights the calculated output for our system, given the latitude and orientation of our roof and the peak capacity of our system is 1393kwh per year. The first meter reading was on 28th August 2010, as of 25th August 2011 the reading is 1362.9kwh. So the measured output is 98.5% of the predicted output – not bad at all! Our import from the grid for the same period was 1896.2kwh compared with an annual consumption of 2397.5kwh in the previous year. So a 20% reduction in consumption and generation of 57% of our pre-installation level. The difference here is because our peak generation (mid-late morning) does not match our peak usage (early evening), since we can’t store any electricity the excess goes onto the grid. These figures are illustrated graphically below:

consumption

We receive the feed-in tariff and payments for exported electricity from our supplier, npower. This seems to be a small scale operation since to set this up you interact with named individuals who don’t change! So far we’ve received two cheques from them for £105.29 for the period 16/9/10-04/03/11 and £174.38 for the period 4/3/11-21/5/11. I should probably go prod them about whether they want another meter reading.

We can dig a little deeper into the data, below I show our monthly electricity consumption (red/green lines) from the grid for the last few years along with the last year of solar generation (the blue line).

monthlyconsumptionOur electricity consumption has been fairly constant through the year with a hint of an increase during the deep winter months due to the shortening days and an increased use of electric lighting. Since about March this year our electricity consumption has been significantly reduced compared to previous years, offset by our solar generation. This pattern wasn’t maintained in the September / October / November last year – I think because I was at home (using electricity) for an extended period following an operation.

The amount of solar generation varies smoothly through the winter months but seems to plateau during the summer. We did have a week of zero generation when the panels were covered in snow. I suspect in principle that the average power generation will vary sinusoidally through the year, since the variation in day length is sinusoidal, but that this can disturbed by “weather”, in particular the figure for May includes the very sunny Easter period without this boost the curve would have varied smoothly through the summer rather than plateauing.

In summary: we’ve generated almost exactly the amount of solar electricity we anticipated which amounts to nearly 60% of our annual consumption of electricity.

Aug 27 2011

Living in code

Eric Schmidt, chairman of Google is in the news with his comments at the MacTaggart Lecture at the Edinburgh International Television Festival. The headline is a general criticism of the UK education system but what he actually said was more focussed on technology and in particular IT education: bemoaning the fact that computer science was not compulsory and what of it that there was about the use of software packages rather than how to code.

I was born in 1970, and learnt to program sometime in the early 80s. I can’t remember exactly where but I suspect it was in part at the after-school computer club my school ran. A clear memory I have is of an odd man who’d brought in a TRS-80 explaining that a FOR-NEXT loop was an instruction for a computer to “go look up its bottom” – this was at a time before CRB checks. My first computer was a Commodore VIC-20, Clive Sinclair having failed to deliver a ZX81 and the BBC Micros being rather more expensive proposition than my parents were willing to afford.

Many children of the early 80s cut their teeth programming by typing in programs from computer magazines; a tedious exercise which trained you in accurate transcription and debugging. Even at that time the focus of Computer Studies lessons was on using applications rather than teaching us to program although I do remember watching the BBC programmes on programming which went alongside the BBC Micro. As I have mentioned before, programming is in my blood – both my parents were programmers in the 60s.

About 10 years ago I was teaching programming to undergraduate physicists, from a class of 50 only 2 had any previous programming experience. The same is true in my workplace, a research lab where only a small minority of us can code.

Knowing how to code gives you a different mindset when approaching computer systems. Recently I have been experimenting with my company reports database. The reports are stored as PDF files; I was told the text inside them was not accessible – now to me that sounds like a challenge! After a bit of hacking I’d worked out how to extract the full text of reports out of the PDF files but then code that once worked stopped working. This puzzled me, so I checked the text that my program was pulling from the database and instead of being a PDF file, it was a message saying “Please don’t do that"!

At the moment I’m writing a program that takes an address list file, checks to see if the addressees have a mobile phone number and if they do uploads it to an SMS service, spitting out into a separate file those that do not have a mobile phone number. To me this is a problem that has an obvious programming solution, for the people who generate the address list it’s a bit like black magic.

These days we are surrounding by technology bearing code, just about every piece of electrical equipment in my house has code in it, but it seems that ever fewer of us have been inducted into the magic of writing our own code. These days there’s just so much more fun to be had from programming: there are endless online data sources and our phones and computers have so many programmable facilities built into them.

At what age can I teach my child Python?

Aug 24 2011

The British sport of bashing the bankers

It’s very popular these days to blame the “bankers” for the recession, and indeed “bash the bankers”. No doubt some of this enthusiasm is down to the fact that “bankers” sounds a bit like “wankers”, and many gain a simple pleasure from this recognition.

Finance (or banking) meant that I could afford to buy a house costing £50,000 with a salary of only £25,000 (this was some time ago!), and investment means that companies wishing to grow can do so without having to painstakingly build up cash reserves by trading. Dealing in these investments is what will help pay for my retirement through my pensions – this is true for both my Universities Superannuation Scheme and my company pension. Insurance helps us to cope with financial shocks we could not otherwise bear, the premiums for this insurance are often invested so reducing the amount of the premiums.

Banking is a mild confidence trick, it generates extra cash on the basis of anticipated future income. The crash happened because banks lent to people who, it turns out, couldn’t realistically be expected to provide that future income. On realising this the banks found they had promised the provision of rather more money than they had access to and flapped around trying to call that money in. More specifically, in the US, banks were giving mortgages to people who didn’t have jobs but who could “afford” a mortgage because “of course” the value of the properties was always going to increase and so the interest on the mortgage would be covered by the rising house value. This scheme worked because these dodgy mortgages were bundled up together and then traded. The bundling reduces the risk, as long as there is no systematic shock that effects all of the mortgages in the bundle.

The bank bailout was not a cash gift in the sense that you might give me £50 for my birthday, it was money to give the banks confidence to keep lending out money which many of us need to live in the manner to which we have become accustomed. In a way the current lending targets for banks are perverse: we’re in the position we are in now because the banks lent more generously than was wise – now we’re encouraging them to lend more than they would otherwise wish.

The bank hardest hit by the crash in the UK was Northern Rock, not a bank engaging in particularly aggressive or exotic trading, rather one that gave the opportunity of owning a house to rather more people than it was strictly wise to do so. In retrospect you could see the seeds of this over-lending 10 years ago, when I was offered a mortgage 4x joint salary, or when you saw all those programs featuring people in their twenties who had £20,000 and above on credit card bills built up on purchases they didn’t need and couldn’t afford.

This isn’t to say the financial sector is without faults: they have a habit of selling products to people who don’t need them (like that mortgage protection plan you sold me Cheltenham and Gloucester), they invent financial abstractions which no-one has a hope in hell of understanding and, because they preside over large money flows, they are able to pay themselves very nicely by extracting a small charge from those vast flows whilst many people are not doing so well.

For me this is personal: my brother has worked in the IT departments of several investment banks, currently the town where I live is facing the possibility of 3,500 job loses because the Bank of America may be closing its credit card handling centre. I don’t want the 3,500 or the one to lose their jobs.

It’s easy for politicians to piggy-back on this enthusiasm for banker bashing but we should be aware that many of the things we take for granted are built with the support of the financial industry.

Aug 21 2011

The Sandstone Trail

SandstoneTrailCropped

The Sandstone Trail walks (click to go to Google Maps)

These days we frequently hear stories of heroic acts of walking: to the Poles, across the Andes, up the Amazon, often undertaken at great speed or under conditions of considerable disability.

This little post is a record of our trek down the Sandstone Trail, 34 miles close to our home in Chester. Our route, drawn from “Circular walks along the Sandstone Trail” by Carl Rogers, adds up to a total of 77 miles. These distances are the sort of things that serious trekkers would cover in less than 24 hours, probably combined with a swim and a 100 miles cycle. Our effort was rather more leisurely – it took us about 14 months. Traditionally we walk on a Sunday morning, usually finishing before lunch.

The Sandstone Trail is covered in 13 walks:

  1. Frodsham
  2. Manley Common
  3. Delamere Forest
  4. Primrosehill Wood
  5. Tarporley
  6. Beeston Castle
  7. Peckforton
  8. Burwardsley
  9. Rawhead
  10. Hampton Heath
  11. Malpas
  12. Tushingham
  13. Whitchurch

These range in length from 5 to 8 miles.  To start off, here is some of the eponymous sandstone, in this case from above Frodsham:

Sandstone

Sherwood Sandstone Group from above Frodsham

The sandstone is from the Sherwood Sandstone Group laid down in the Early Triassic, 250 million years ago.

The small town of Frodsham lies close to the Mersey Estuary and after you have climbed up onto the sandstone heights above the town you get a fine view towards Liverpool and across the industrial works at Stanlow refinery and Runcorn. I’m rather fond of these, Runcorn is a fine collection of pipes, tubes and the odd ball shaped thing whilst the Stanlow refinery looks like something out of Bladerunner; at night they are lit up with gas flaring off on some of the chimneys.

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Stanlow Oil Refinery

The walks to Primrosehill Wood are rather pleasant, at Manley Common we were inspected by enthusiastic pigs.

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Pigs!

We also saw a lot of cows:

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Cows looking towards Beeston Castle

And a llama (rather further along the Trail):

Llama

LLama

The llama was very inquisitive, perhaps overly so since there was a small diversion around its field with a note highlighting that dogs and walkers with sticks had interacted with it rather more than was strictly desirable. As we walked past its field it followed us very closely over the fence with a look of what could have been either llamaly inquisitiveness or aggression.

For me the Tarporley and Beeston Castle walks were a bit of a slog, they span the Cheshire Gap, a flat area of clay farmland. The Beeston Castle walk in particular comprises a trip out into the plain and then back again with the Castle the sole point of interest for the whole walk. The Castle is pretty impressive but you have to pay to get in, so we didn’t.

Beeston Castle Gateway

Beeston Castle Gateway

Beeston Castle

Beeston Castle

The next three walks, Peckforton, Burwardsley and Rawhead are my favourites, at this point the Sandstone Trail heads up onto a wooded ridge with lovely views in all directions. The Peckforton Estate has left some classy stonework along the route.

View from Bulkeley Hill Wood

View from Bulkeley Hill Wood

Haunted Bridge

Haunted Bridge on the Peckforton Estate

Misty view from near Rawhead

Misty view from near Rawhead

The last four walks: Hampton Heath, Malpas, Tushingham and Whitchurch take you off the  ridge for more walking across rolling farmland with a couple of stretches along the canal. We did manage to get very wet one day:

Ian

Me, wet

This was achieved by crossing a field of oil seed rape not long after heavy rain, I think this is the wettest I’ve ever been following a walk (and I’ve walked in the Lake District!). As you can see the crop reached a height of approximately five feet and held an awful lot of water.

I must admit to not being too fond of this type of walking but we could not leave walks undone. This little arch, in Jubilee Park in Whitchurch, marks the end of the Sandstone Trail.

End of the Sandstone trail

End of the Sandstone trail

You can see the GPS tracks I captured on the walk here in Google Maps.

Aug 19 2011

Surprise!

Sharon (aka @happymouffetard, or my wife Mrs Hopkinson) is pregnant! Working title for the new member of the family is Beetle. Below you can see images from the dating scans, the due date is 21st February. In real life Beetle had a bit of a thrash around and demonstrated various bits of anatomy. 

Scan1

Scan2

Scan3

Technically @happymouffetard is described as “Geriatric Primigravida”