Blogs
The Changing Face Of Solar Energy
This is a guest blog post by Eduardo Estelles, Technical Director of Logic Energy , a GEN Supporter.
Solar energy brings to mind rectangular panels positioned in endless rows in a desert landscape, carefully aligned with rooftop edges, or extending like wings from an orbiting space station. Modern solar panels, and future solar cell designs, may bear little resemblance to these former icons of solar energy.
Crystalline silicon cells have been commercially available since 1954, so it is not surprising that they are the primary image associated with solar power. Inside of each panel is a collection of thin silicon wafers that have been sliced from ultrapure silicon crystals. They are carefully doped with the requisite semiconductors and are perfectly positioned behind a layer of protective glass.
Silicon is actually a poor material for solar cells. It does not absorb light well, and a solar cell requires a wafer that is several hundred microns thick in order to generate electricity. It remains in use today because it is stable and is relatively efficient. Highly efficient silicon crystal solar cells today achieve an efficiency of only 22 to 25 percent.
From a layman’s point of view, this is not a problem. Reaping 25 percent of a limitless supply still results in limitless energy. From an engineering perspective, the issue is more complicated. Low efficiency means that larger solar panel surfaces must be used to convert sufficient quantities of sunlight to electricity. In most cases, the surface area of a residential roof is simply not large enough for this task.
The use of amorphous thin film technology is an approach designed to embrace low efficiency and install solar cells over larger surface areas. Instead of using silicon cut from expensive crystals, thin film technology deposits very thin layers of amorphous silicon over inexpensive substrates such as glass and steel. Although the efficiency is even lower than crystalline silicon cells, the thin films are much less expensive to produce and can be incorporated onto much larger surface areas. Clear glass windows can be used as thin film solar cells. Roofing shingles and exterior siding can be coated with thin films.
In many cases, the construction material is replaced by thin layer photovoltaic material to support Building Integrated Photo-Voltaics (BIPV) (see our article on BIPV). The cost of the system is lowered by the use of thin film technology instead of expensive silicon crystal technology, and the elimination of conventional construction materials partially offsets the cost of the BIPV materials. The entire outer envelope of a building can essentially be a solar cell. Thin film technology is also attractive because it produces electricity, albeit at lower efficiencies, at much lower light levels that crystalline silicon technology.
An advance in solar technology that may soon be commercialized is the use of quantum dot technology. Instead of creating flat layers of solar cells, quantum dots produce surfaces that are covered with microscopic cones of photovoltaic materials. The conic stacking of these materials allows for incredibly dense surface areas over a very small space. Photons easily penetrate deeply into the valleys surrounding quantum dots, and the dots can be constructed by stacking materials with differing band gaps to maximize photon absorption and utilization.
Just as with other technological advances, so too the face of solar energy is changing to deliver more for less.
---
Scottish based Logic Energy exports to 25 countries in the UK, Europe and South America accounting for 40% of turnover. Customers include large corporate construction companies, local authorities, schools, renewable energy consultants and environmental organisations such as SEPA and Community Energy Scotland.
Eduardo Estelles speaks frequently on the current issues affecting the renewables sector and on the massive potential of wind, solar and heat installations in Scotland and elsewhere. Logic Energy is now looking to raise funds for research and development into solar energy monitoring as well as investment for further international expansion for wind.
Domestic energy consumption linked to affluence
A few weeks ago The Guardian published some great new maps of domestic energy consumption from figures published by DECC at the ‘neighbourhood scale’.
These figures have been mapped for Britain at: http://www.guardian.co.uk/news/datablog/interactive/2012/apr/02/energy-use-map-electricity-gas
For anyone that hasn’t had a play with map yet, we’d recommend exploring areas you know. If you find some interesting trends leave us a message below.
The two key datasets are average gas consumption per gas meter and average electricity consumption per meter. Just to help you get your head round this data, we believe that OfGem has been able to take consumption data for every 'domestic scale' meter in Britain and produce an average (per meter) figure for each zone. There will be situations where average household sizes in some areas are larger and you would therefore expect consumption to be higher – if you factored in the average household size per zone then you could normalise the figures to take this into account.
The zones being used (Medium Super Output Areas in England and Wales, Intermediate Zones in Scotland) are roughly similar in terms of population size (approx. 5,000 population per zone). The effect of housing density is indicated by the size of the zones. Small zones indicate high densities and a higher percentage of flatted dwellings. Large zones in urban areas often indicate lower density detached or semi-detached suburbia. Flats are known to have lower heating energy requirements per square-metre than terraced houses; hence most of the smallest zones have low total consumption (green colour). Terraced houses, in turn, need less heat than detached houses; hence larger zones containing suburban semi-detached or detached housing, or large city centre town-houses, tend to have the highest gas consumption (coloured red or purple).
Here are a few of our observations:
- Analysing on-gas-grid areas and off-gas-grid areas on the same electricity map can be highly misleading. It would be better to extract off-gas-grid rural areas and view these on a separate map. It is also not clear exactly which areas are (wholly or partially) off-gas-grid, as some parts of Scotland appear to be ‘on-grid’ even though gas is known not to extend to all parts of particular zones.
- Like many of those who added comments on the Guardian’s page, there are clear associations (both with per meter data and gross totals) between areas with large, detatched properties (generally more affluent) and higher consumption of both gas and electricity per meter. To heat these larger properties (which may be historic and ‘hard to heat’) will require more energy. The classic geographic juxtaposition in Glasgow illustrates this with Drumchapel (high levels of poverty, relatively low levels of consumption – and much higher density housing) and Bearsden (highly affluent, relatively high levels of consumption – and mainly large houses).
In general rural areas appear to have higher electricity consumption (per meter) than urban areas. Some of this pattern will be explained by rural properties being off-gas-grid and using electric heating instead. However a significant proportion of rural housing will be using oil for heating.- Gas consumption data will be heavily influenced by access to mains gas. Where areas do have access to mains gas, then it appears affluent, low-density suburban and rural areas consume more ‘per meter’ than less affluent areas – and also less than highly urbanised areas. Note the obvious suburban red ring around both Manchester and London for gas consumption ‘per meter’ (see right)
- Most flatted properties are small and therefore will contain less people ‘per meter’ than large suburban houses. This will reduce energy consumption compared to 4 – 5 person houses. It might therefore be useful to correlate energy use ‘per meter per occupant’.
- There are large areas in Scotland, in particular without access to mains gas. They have higher electricity ‘per meter’ consumption as a result of their reliance on electricity for heating, either wholly or to supplement poor-quality oil or solid-fuel heating.
- This data appears not to highlight a significant north-south difference. However, checking through some of the DECC information, it would appear that the data has been normalised against climate data, and therefore any north-south divide would not appear.
- One comment noted in the DECC associated report is that there is
a “lack of a reliable domestic industrial/commercial sector split for consumers with low gas consumption. This is because the gas industry uses a crude 73,200 kWh level as the cut off point for defining customers as domestic or commercial/industrial. The implication of this is that only around half a million businesses are allocated to the industrial/commercial sector, with around 2 million small and medium businesses allocated incorrectly to the domestic sector. DECC is currently looking at improving the allocation of businesses to the industrial/commercial sector by using information from the Inter Departmental Business Register (IDBR).” This means that, where you might have a lot of small-to-medium businesses (e.g. shops and offices below flats) their gas consumption data will also be incorporated into the domestic data.
Some conclusions:
- It is perhaps no surprise that areas with higher energy consumption are likely to have a high proportion of large, detatched (and possibly historic) houses. However it is useful to validate this. We suspect that even if you were to add a 'per head' factor to this data you would still find the same pattern - indeed this could well exacerbate it!
- There should be considerable potential for cutting energy consumption in affluent on-gas-grid areas through energy efficiency measures, although challenges to this might include the fact that the financial incentives are weaker, they are potentially harder to heat (historic) properties, and there is likely to be a reluctance to invest public money in reaching this audience.
- A significant shift towards greater energy efficiency measures and the installation of heat pumps and biomass heating in off-gas-grid rural areas could reduce ‘per meter’ electricity consumption. But, until the data for oil consumption and other fuel sources is available, we will be unable to compare on-gas-grid properties with off-gas-grid properties comparatively.
- Overall, the source data offers a great deal of value if handled with care. With further analysis, areas of similar housing type could be compared with each other to highlight those with high and low consumption levels and, more importantly, what is happening in these areas that could explain the variation. The data should allow local authorities and others to target areas with high consumption. Campaigns could be developed for these areas to encourage them to take action to reduce their consumption levels. However public spending on pro-active social marketing to affluent residents may not be considered high priority by many local authorities!
- The implications of this in terms of policy are far-reaching. You might be feeling aggrieved that major programmes like the Green Deal appear to be aimed more at cutting consumption for those households that already have lower energy bills! [Maybe there's more of them and they are considered to be easier to improve?] But the policy people also need to find ways to persuade affluent households to make significant cuts to their consumption. How about "you jump to the next council tax band if you score D or below for your EPC"? This would be neat and relatively easy to implement - except that local authorities would then get the additional revenue and they are not renown for rolling out energy efficiency programmes to the masses.
If you have your own observations and conclusions, perhaps for an area you know, tell us more below. If you have suggestions for policies to persuade those living in larger properties to cut their consumption do post them!
New Kingspan 50kW prototype turbine spotted..
Thanks to a keen eyed turbine spotter who has alerted us to a new 50kW prototype turbine. This planning application was submitted in Northern Ireland for a new 50kW Kingspan Renewables turbine. The turbine elevation drawing is here - the design is well worth checking out!
So if you've been wondering what the wind engineers at Kingspan Renewables have been up to since their purchase of (some bits of) Proven Energy then here's a good indication! They've certainly be quick to develop a new operational prototype (unless it was under development before the Proven deal).
Obviously it will have to go through all the MCS certification processes before it can qualify for the Feed-in Tariff. So the earliest it could probably be available for sale would be 2013.
What would be its main competitors? The main ones right now would be the Endurance 80kW (it’s not a 50kW) and the still-to-be-launched C&F 50kW. Both have a considerable head-start so Kingspan are going to be playing a game of catch-up. Let's hope there's still enough space in the market for it by 2013 – and FiT means it’s still attractive! There are also others in this space which we list in our Medium Wind Turbines article.
The nice thing about 50kW turbines is they are relatively affordable, they can offset considerable on-farm electricity consumption, and you have the option to put two of them on one site and hit the 100kW FiT 'sweet-spot'. In terms of scale they also tend to be much more acceptable to planners and local communities. So you can see why Kingspan are keen to have a product in this space.
If Kingspan get it right then, despite their late arrival, they could have a major impact on this small wind market. While Kingspan Renewables has been set up as a separate business, it is part of a much larger Kingspan Group of companies that offers the scale of operation and depth of pockets that few if any others in this market space can match. In theory this should give consumers a considerable degree of confidence they can cope with the ups and downs of this market and still be in business in 20 years time. They will need a turbine design that's acceptable to planners of course!
