The Greening of Hedgerley Wood

Trimming Trees

July 11th, 2010

As well as waiting for the new inverters, it’s clear that we can prevent a lot of shading by trimming a few of the trees.

So our friendly tree surgeons came in and cutting a few laterals opened up a surprising amount of sky.

We’ll start measuring the impact in conjunction with the new inverters in August.

To be sure that we are saving our 10% as part of the 10:10 campaign, we will have to factor in our total electricity use which is in any case too high. It looks as though the new PV will save us about 20%, but only for the second half of the year. And to reduce our emissions overall we will have to keeping looking at our other energy uses like the mileage on the Prius.

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Shading Problems

July 11th, 2010

The first 3 days have been very sunny and have produced a total of 26 kWh. This seems disappointing and doesn’t suggest the system will achieve the promised results over the year.

Clearly shading from the trees is a major factor. The attached montage shows the shadowing against the output (on the main inverter only since the smaller one does not have a display) for each hour, plus 10.30 as the point where the output suddenly improves.

These results then sent me back to the original documentation from Ardenham Energy. The output they promised in their proposal letter was 2,448 kWh/annum. Whereas in the document sent after the commissioning this has gone down to 2,004 kWh/annum. Why such a significant change? This would seem to be a reduction of about a fifth in what we were expecting for the quoted price.

Ardenham’s reaction was very helpful. They looked into it and found that their original quotation had omitted consideration of the shading factor. Since we were not getting what we had paid for, they made a really good offer - to change the inverters to the newly developed ones when they become available. These prevent the shading of one panel pulling down the output of the rest, so should restore our promised annual output to 2,448. These new inverters will be available in August, so we shall see.

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PV Installation Day

July 10th, 2010

It seems all solar installation firms are very busy, and it was mid-May before Ardenham could find a slot. On day one scaffolding was erected on the whole length of the south side of the house. The plan was to put the 16 panels on the highest part of the mansard roof. The following day installation began.

Rails were fixed through the slates and the panels came with a clip-fixing system that make them pretty simple to secure to the rails.

The panels themselves are made in China and sold by Amerisolar. They have a capacity of 180Wp each.

It took until late on the third day before the last of the 16 panels were in place.

The electrical work had been progressing in parallel and we were all set for the moment of switch-on.

But it was too late in the evening and very little power was produced until the following days. Then the calculations could begin.

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Time for PV

July 10th, 2010

We’ve been thinking about the economics of putting PV panels on the roof, particularly to offset the power requirments of the ground source heat pump, which takes 2.8 kW when it’s running. Although we are getting this electricity from Green Energy who use only renewable sources, it still costs a lot and anyway the capacity isn’t currently there for the whole country to use renewables. So, a good idea but a pity it’s so expensive since it could help our commitment to saving 10% of our emissions as part of the amazing 10:10 campaign. We were also worried about the degree of shading by trees - more on that later.

What has suddenly changed the cost equation is the Labour government’s introduction of the Feed-in Tariff. This pays 41.3p for every kW we generate. What’s so amazing is that they pay this much (around 3 times the cost we buy it at) whether we use it or export it. So we have a double saving. It’s a no-brainer for middle class families that have the space and capital to invest in it.

So I looked around for a reputable installer, having heard there were a lot of pirates out there. I came up with Ardenham Energy of Aylesbury, who have turned out to be excellent. Following a site survey, they quoted £11,316 to install 16 panels with a total output of 2.88kW. This included the scaffolding and the rather complex electrical installation, since 2 inverters to be needed for this capacity.

Very important at this stage is their expert prediction of the likely annual output in practice. They estimated this at 2,448 kWhours. This would provide a feed-in tariff of £1,011, a saving of £147 and an export return of £37, making a total each year of £1,195. So the system would pay for itself in 10 years and provide this much income and savings thereafter. And of course it would be mean that a proportion of our electricity use would be entirely emission free.

The only snag that arose was the discovery that the current generation of inverters have the strange property that if even one of the 16 panels is in shade, the output of all of them is reduced. There is a new generation of inverters to avoid this but they were not available at the time.

So we accepted the quotation.

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Bikes to go

April 13th, 2009

To the new Prius we’ve added excellent bike racks at only £65 each. They hold the bikes really well, so now we’ve been able to get beyond the impossible local hills to find some really nice cycle tracks. Feeling much better and a little fitter after this week’s eco holiday.

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Battling with the stove

February 26th, 2009

We’ve been keen for a long time to install a wood-burning stove to replace the old aga. The problem was always going to be the solid concrete chimney breast built in the 1930s. In the event it took two very persistent workmen from the Czech Republic most of a day the hammer through a big enough opening to the pull through the chimney lining.

It wasn’t until the second day that they managed to get it all installed.

Since then we’ve been only moderately pleased with this Clearview model. It’s heats this side of the house pretty well, but it uses more logs than we expected and it doesn’t seem to stay alight as it should when the vents are closed down. Maybe our chestnut, beech and oak logs are not ideal. Or maybe we have to learn more about the optimum settings. We’d been looking forward to coming down to a warm kitchen in the morning.

However, the ground source heat pump has performed heroically throughout this very cold winter and has kept the whole house really warm.

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Almost Electric

February 26th, 2009

It’s a long story but at last we have gone for a Prius.

Ideally we would have liked an electric car and my researches at the motor show turned up a few possibilities:

But then I went to a really interesting lunch at the World Economic Forum in Davos, where the leading manufacturers were discussing their plans for launching electric cars in the next few years. What I picked up was the very strong advice that this was not the right time to buy electric - at least for a family car. The reason is that battery technology is evolving rapidly, so the plan for the future is to sell the car and battery separately - like a torch. That way batteries can be upgraded and even exchanged at future electric filling stations. But buying a car with a fixed battery now would render it unsalable in a few years. And it will be, by all accounts, at least three years before the new electric cars will be available in Europe.

So the best option for the next few years seemed to be the Prius, not only for the low emissions but also because I’d really enjoyed driving them in the States. Plus Andrew has one and is very fond of it. Second-hand prices turned out to be reasonable. And so far we are really delighted with it.

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Dumping Ecotricity

July 25th, 2008

It seems that this issue has come out because companies have only recently been required to publish the fuel mix. And it’s going to shock a lot of people.

I had an authoritative response from someone in the business (who had better not be named):

“I am not surprised at this. Ecotricity is run by Dale Vince… He has persuaded everyone that ecotricity is the greenest of the green, not because it is, but simply because he says that he will plough the profits of his business back into only developing new renewable energy projects. At one level I understand this logic but when I look at it from a business perspective this is just what any “renewable energy company” would do. The fact is that RE is very profitable. It is only recently that companies have had to disclose their energy mix, and so you can actually see that…for many years honest, ethically minded people thought that buying from Ecotricity was the very best they could do when in fact a large proportion of their energy was coming from Nukes!!

This really is a triumph of marketing over substance and… I strongly suggest that you move back to Good Energy who do actually sell 100% renewable.”

So, taking this advice, we’ve switched back to Good Energy. According to electricityinfo.org they are the only UK supplier using a 100% renewable fuel mix.

Back to to the Carbon Account to update our footprint.

Posted in Lighting, Heating | No Comments »

A new calculator and a surprise

July 11th, 2008

I’ve just got round to signing up to Torchbox’s carbon calculator - The Carbon Account. It’s quite the best I’ve used for a number of reasons. It logs detailed information about your particular vehicles and your energy supplier, looks up the latest information on them and presents your progress to reducing your carbon footprint in a really clear, evolving display. The result was higher than I expected (3.57 tonnes) but the reason for this turned out to be rather shocking.

The Carbon account uses information on the fuel mix used by the different energy suppliers from here. We were with Good Energy and they show up as using 100% renewable sources. But we switched to Ecotricity precisely because we were told that they were more truly green. But based on this information, they in fact only source 24% from renewables - with the same percentage coming from coal.

So what’s this about? Going Ecotricity’s web site, I can’t find any reference to their fuel mix. Instead they make great play with the fact that they are the largest investors in new renewables. But is this really the point? And should we switch back to Good Energy?

Posted in Heating, Taming the Car | No Comments »

glorious trees

May 26th, 2008

An interesting factoid from Green Futures.

I was amazed when I first read it and did some quick calculations. We are lucky enough to have around 350 mature trees (mostly beech as it happens) in our plot here at Hedgerley. Some are growing quite close together, so I took 200 as a round number to be conservative. Then at 1g per tree per minute, that would mean we are saving 105,000 tonnes of C02 a year. Or as an alternative prize we could claim guilt-free driving of 250 million kilometers. Crazy surely?

So I wrote to the editor, Roger East. His very charming reply said ‘we’ve goofed’. It should be been 1kg per half hour. They’ve corrected it now on the site.

But it’s still a very significant finding for us. It means that our woodland is saving us 10 tonnes a day, or 3,504 tonnes a year. Which makes our carbon footprint minus 3,500 tonnes.

But what does this mean? Clearly not that we can fly wherever we like and forget about our plans for PV. But it does mean we should be careful about any tree that we cut.

And we only have this saving because we happened to choose buy a house in a wood - it didn’t even cost more than a house not in a wood. And there’s more.

At around 100 trees per acre and with an acre of woodland costing around £2,000, this means that an average person with an average footprint of 10 tonnes could genuinely (not notionally) soak up their emissions at a cost of less than £20. Planting one tree in your garden or in shared woodland would, when it’s mature, go on saving around 18 tonnes of C02 a year.

And what about a campaign for more trees in our towns? Why not one in front of every house - with the householder able to claim the reduction to their carbon ration so long as they look after it?

So is all this still too good to be true? I’m still looking for the original source of the research in New Zealand that came up with these figures.

Posted in Planting Trees | No Comments »

The Greening of Hedgerley Wood

Trimming Trees

Shading Problems

PV Installation Day

Time for PV

Bikes to go

Battling with the stove

Almost Electric

Dumping Ecotricity

A new calculator and a surprise

glorious trees

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