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Topic Title: E&T magazine - Debate - Is home-brew solar power the future?
Topic Summary: Is home-brew solar power the future?
Created On: 13 February 2013 10:54 AM
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 13 February 2013 10:54 AM
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Solar energy already makes economic sense and its applications can be increased immediately.

Solar energy may appear to have the potential to be economical but there are hidden costs.

The argument for:
Generating your own electricity is akin to 'home brewing' beer. I live in Cornwall where my grid supply comes either from Hinkley Point (85 miles) or from Didcot, which is 205 miles away. A kWh generated at Didcot costs about 5p. But by the time it has passed through the National Grid, to Western Power Distribution, to one of the 'Big Six' supply companies and to my house, the daytime cost has risen to about 20p. To pay this, as a 20 per cent taxpayer, I would need to earn 25p.

Instead, I have installed 4kW of solar PV ground-mounted in my garden (it will make an excellent garden shed) that today would cost £5,000. Adding £1,000 for the replacement of the inverter at some stage should give me 4,000kWh per year for 30 years (I recently saw solar PV panels that were 34 years old and generating 90 per cent of their original output). Amortising the cost by dividing it by the lifetime output gives the home brew cost of my electricity as 5p/kWh, a saving of 20p/kWh. And this is without any subsidy.

Home brew DC could become the norm with the grid providing back up and power for heavier appliances.

The argument against:
Even if solar cells were massively more efficient and less expensive, they would only serve to expand energy supplies and accelerate overall demand. Solar cells shine brightly within the idealism of textbooks, but experience reveals a scattered collection of side effects and limitations.

The real clean energy is less energy. If we wish to leave a smaller footprint on the Earth and back away from resource scarcity we should develop strategies to use far less energy overall, not subsidize more energy production.

Any number of conservation strategies offer far higher dividends than solar cell investments. We could question growth in energy production, economy, and population. All of these initiatives are left under-represented as we unwittingly rush to celebrate energy firms who are building the next round of ecological disaster machines.
 13 February 2013 03:31 PM
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Langage Power Station in Devon at 895MW would surely be a more local source of energy for Mr Williams to mention in his opening sentence.

 13 February 2013 08:08 PM
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So we have a choice between two extreme green viewpoints: one a pro-solar CEO of a solar company, the other an anti-solar green who advocates energy rationing and state-enforced population control.

Where's the button to vote for ' none of the above '?

I would also like to check the brigadier's figures which purport to show his solar panels are cost effective without subsidies. When I performed the same calculations myself I found the complete opposite - that they would never pay for themselves without the massive 470% subsidy then being offered by the loonies at DECC.
 13 February 2013 10:02 PM
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You're probably sitting on it.

 13 February 2013 10:08 PM
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The estimate of 4 kWh per year from 4 kW peak installed is optimistic. For instance, my 3.5kW peak array generated 2719 kWh last year, January 1 to December 31st. Although you may have seen an array 34 years old @ 90% efficiency, the manufacturers of my panels (and all others that I have seen) quote an average of 25 years at 90%.

Thus, allowing for the same percentage generation, the a lifetime of 25 years and a reduction in efficiency over the lifetime, a more realistic "home brew cost" for a 4 kW array would be around 8p per kWh. Still substantially lower, but you have to remember you get nothing at night.

 14 February 2013 11:30 PM
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What part of cloud cookoo land does Gage Williams live in, peak generation will occur in mid summer but peak consumption will occur in mid winter - so that roughly half of the localy generated electricity will be sold to the suppliers at a pitance to be purchased later at the going high rate. Like Gage I am retired and at the age of 80 I am interested in what happens today not what happens over a 30 year time span. Most people live in urban areas so do not have the oportunity to install PV Panels, even if they could domestic consumption only accounts for 30% of the UK total. Finaly a Solar Park generates about the same as a modern single wind turbine. roughly 0.001% of the Uk total demand.

Lionel J White
 15 February 2013 05:37 PM
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Unfortunately the nature of these debates ensures that those putting the arguments exaggerate the claims.

Let me declare an interest, I am a great fan of solar energy but it is clear to me that Gage Williams exaggerates the claims for pv solar. The cost is actually higher, the lifetime probably lower. Using dc direct is not a solution, the output from the cells needs regulating and efficient regulators are almost as complex as inverters. Electric tractors might be an attractive notion, but are really not going to make any noticeable difference to pollution.

None of the currently practical renewable sources provide continuous power. My solar array produces one seventh the power in winter as summer, practically nothing on a very cloudy day. Britain is not geographically a good place for solar, it is too far north. Storage schemes such as that described by Gage Williams are needed to even out fluctuations from all the renewable sources but the cost and maintenance of such schemes should not be underestimated.

Ozzie Zehner overemphasizes the drawbacks. His major argument is that solar cells are not zero carbon technology and require energy and pollution to be manufactured. All renewable energy sources need energy to produce them, and pollute in the process. He is not even right to say that the real clean energy is less energy; the only clean energy is no energy. But the less energy message is vital.

As with the majority of these debates, both are right. We must reduce energy requirements by improving efficiency, but we need energy, and solar has and will continue to have an important role in the energy mix. Its nature needs large area so "home brew" is a good way to implement it.

Note, pv is not the only solar technology. Spain has a near-1GW concentrating solar plant which produces steam using mirrors; and it is possible to store steam. But they have the location and the sunshine!

David Walker

Edited: 15 February 2013 at 05:47 PM by davidwalker2
 20 February 2013 08:10 AM
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As Ipayyoursalary says neither answer is complete.

The economic argument for misses out an important point.

The additional 20p per unit is effectively your guarantee of supply 24hrs a day 7 days a week. The power can come from Hinkley Point, Didcot, Fawley or France but you get it whether the sun shines or not.

If you start trying to compare like with like and decide you would like to have some lights, maybe television or music, perhaps go down to your shed and use your lathe when it is dark then the PV system costs will increase rapidly. Depending on the system configuration you will need storage batteries (limited life if regularly deeply cycled), a second inverter or a second DC wiring system and some sort of grid link or standby generator for when the batteries run down.

If you take the other view point that you will use your own PV electricity when it is cheaper and the grid the rest of the time you have the same problem as with intermittent wind power. There will have to be a significant increase in the amount of fast response, and hence expensive, sources connected to the grid, spinning reserves, pumped storage, gas turbine etc which will increase the costs for everyone and lower the system efficiency. Intermittent grid connected generation is effectively a parasite.

The against argument doesn't really offer anything concrete. We all know that as long as the population keeps increasing energy consumption will increase even if consumption per capita falls. PV does have place as part of a power supply for remote off grid systems. A remote telephone or data collection system powered by a combination of wind, PV and storage battery makes sense, multi MW PV probably doesn't make sense.

Best regards

 18 March 2013 09:56 PM
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I am surprised to see that 70% voted for Gage Williams motion and wonder whether all those who voted actually read his arguments. That PV panels provide shelter for sheep is indeed a point which I haven't considered. It does however seem a rather expensive option and there is not much room for animals to graze in the fields which have been plastered full of PV panels in this area (southern Germany). I presume the farmers who have changed from food production to electricity generation have done so because of the excellent return on investment provided by the generous subsidies guaranteed by the German government, and paid for by private electricity customers who are unable to benefit from this scheme.
There is a need for a serious technical discussion, backed up by realistic figures to support the arguments.
Rob Jones

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