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Solar power brightens up

Solar power is often seen as nice, but a bit marginal in chilly northern countries. The reality is different. There is now over 20 GW thermal of solar heating capacity in the EU, which much of it being in northern countries like Germany, Austria and Denmark.

A lot of it is roof top domestic-scale, but there is also now a growing contribution from large-scale systems. For example, solar district heating is now moving ahead around Europe. The District Heating network in the Austrian city of Graz has 6.5 MW of solar thermal capacity. And further North, Danish collector manufacturer Arcon Solvarme has installed a 10,073 sq. m installation in the village of Gram in the region Syddanmark, and a 8,019 sq. m system in the village of Strandby in North Jutland, which meets 18% of the average energy demand for heating and domestic hot water of 830 households. A third solar thermal system, with 10,000 sq. m, has also been installed in the town of Broager in the south of Denmark. It’s claimed that schemes like this can achieve payback times of 7–9 years. See and

Germany also as some solar/DH projects. Nine research and demonstration plants have been built since 1996, including some with inter-seasonal heat stores. Depending on their size, they can meet 40–70% of the annual heating needs of a residential estate. In Friedrichshafen, a residential estate with some 600 housing units has a solar district-heating system.

PV solar meanwhile is also moving ahead rapidly around the world. The main issue has often been the costs, but they are now falling (some thin-film amorphous Silicon modules are now at below 7 cents/watt), with claims being made that PV will be competitive with grid power in some locations within two or three years. Indeed, it has been claimed that in North Carolina consumer charges in $/kWh for PV-delivered power are now less than for power that might be delivered at some point from new nuclear plants:

Of course PV enjoys subsidies in the US, but then so does nuclear. PV has also benefited from subsidies in the EU under the various Feed-In Tariffs, to the extent that a major market boom emerged, leading to price reductions, which further stimulated uptake. That rapid expansion lead to some cuts backs in subsidy levels in Germany and Spain, since it was claimed that too much extra cost was being imposed on electricity consumers, who in the end pay for the subsidy. But with prices continuing to fall, the extra cost should fall too, and the rapid progress of PV seems likely to continue around the world. One recent area of expansion in the UK, stimulated by the new Feed In Tariff, is on farms – with solar arrays now being installed: see my earlier ‘solar farm’ blog.

Globally there is around 22 GW of PV capacity in place, still much less than the 150 GW (Thermal) or so of solar heating capacity around the world, but catching up fast. By 2020 PV will generate 126 TWh of renewable power around the world, according to the latest International Energy Outlook 2010 from the US Department of Energy. By 2025 it will generate 140 TWh and by 2035, 165 TWh. China alone aims to have 20 GW by 2020. The DECC 2050 Pathways suggests that the UK might have 70–95 GW peak of PV in place by 2050, or more, if we really went at it hard, supplying 140 TWh by 2050 in their maximum scenario.

In parallel we are like to see rapid expansion of Concentrating Solar Power (CSP) in desert areas, with focused solar heat being used to generate electricity as well as CPV, focused solar PV units in deserts, some of this being exported to the EU. The International Energy Agency says 11.3% of global electricity could be provided by CSP by 2050. Others say much more. See my earlier CSP blog.


As solar expands around the world a key issue, which will become increasingly important, is cleaning. Like windows, the cell/mirror surfaces will collect up grime, dust and road grit and that must be regularly removed or else performance will fall – by perhaps 5% pa. Desert dust and sandstorms can also present problems for CSP mirrors – it’s known as ‘soiling’. But it could be that self-cleaning technology developed for lunar and Mars missions could be used to keep terrestrial solar panels dust free. Working with Nasa, Malay Mazumder from Boston University originally developed the technology to keep solar panels powering Mars rovers clean. But now he is working on a terrestrial version.
It uses a layer of an electrically sensitive material to coat each panel. Sensors detect when dust concentrations reach a critical level and then an electric charge energises the material sending a dust-repelling wave across its surface. He says that this can lift away as much as 90% of the dust in under two minutes and only uses a small amount of electricity. Sadly, though ideal for deserts, back in the EU, it probably won’t be useful for bird droppings!

The use of water and detergents for cleaning PV cells and solar heating panels could clearly open up some new environmental issues, but otherwise, as long care is taken to dispose of old PV cells carefully, or better recycle the constituent materials, there would seem to be few negative environmental implications from the domestic use of solar. Apart perhaps from the issue of glare, which is a siting issue, shared with other forms of glazed area. There can be toxic materials/health and safety issues in PV cells production, and some conflicts have been identified with desert wildlife in relation to CSP, but these problems should be amenable regulatory resolution.

Water use by CSP in deserts has been raised as an issue. It not just the water needed for washing mirrors. CSP needs water for efficient operation, as with any heat engine you need cooling. It can be done with air (fans blowing air across radiators) but that’s inefficient (it uses energy) and adds about 10% to the cost. Water-cooling is better, but that’s one thing you don’t have in deserts. However you could import sea water, if you are within reasonable reach of the sea. That’s one idea that being considered for some CSP projects in North Africa – piping in sea water from the Med for cooling, and also for desalination. The pipes could be hundreds of miles long, although that adds to the capital cost and uses some energy. And you’d end up with a lot a salt. But then, to be fair, other energy technologies also need water. A study by Virginia Tech University’s Water Resources Research Center found that conventional fossil fuel require anywhere from 5 to 8 times as much water per million kWh produced as CSP, while nuclear plants need even more – 10 to 20 times as much/kWh as CSP: nuclear plants consume about a gallon of water for each kWh of electricity produced.

Of course, nuclear plants are not (yet) usually in deserts…although with climate change worsening there are likely to be increasing problems in providing cooling water even so. France has already had to shut nuclear plants down in the summer since the exit water temperature was higher than local river regulations allowed. It’s likely to get worse. Getting access to cooling water could be an increasing issue for many land-based energy technologies- solar PV and wind apart.

For more, see and

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