The UN’s Intergovernmental Panel on Climate Change reports has once again called for a “massive shift” to renewable energy. The challenge of curtailing anthropogenic greenhouse gas emissions is considerable, but scientific developments mean that renewables, such as solar power, are becoming economically competitive and a viable option – even in the UK.
Despite Britain’s reputation as a cloudy country, the amount of energy the sun shines down on it still greatly exceeds current and projected power consumption. Harnessing solar power is possible without any impact on land use by using photovoltaic panel systems that can be mounted on top of buildings.
Building solar capacity
England alone has 2380km2 of roof space that, if lined with conventional solar panel technology, could give a maximum energy generation capacity of 380 GWp (one Wp is one watt of electricity generated by a PV system under full sun). This gives an average power generation of around 50 GW – far outstripping the current average UK power consumption of 36 GW.
Solar capacity can be further increased using unprofitable land such as road verges and building facades. Siting solar power systems close to the point of consumption can also help to reduce transmission losses, reducing overall power consumption.
Currently only a fraction of 1 per cent of UK power is provided by solar PV. In Germany, however, a country with similar amounts of sunshine to the UK, solar power provides about 6 per cent of all German electricity annually, and this fraction continues to grow. German solar power helps to meet up to 50 per cent of daytime peak in electricity demand, largely offsetting generation that was previously supplied by gas power plants.
Because solar generation is variable – available only during daytime and more abundant in summer – it must either be stored in batteries or complemented by other sources such as other renewables and flexible gas plants. In Germany, experience has shown that the seasonal fluctuation in solar power is partly balanced by wind power, which is strongest during winter. This potential complementarity of wind and solar resources is also true for the UK.
The UK government’s 2014 solar strategy aspires to an installed capacity of 20 GWp by 2020. This eightfold increase from the current UK capacity of 2.7 GWp is entirely feasible with present technology, as shown by the German example over the past decade.
The target 20 GWp of PV would generate more than 5 per cent of the UK’s electricity demand and could be integrated as part of a technology mix without major changes to the set up of the country’s power system. Further growth in solar (and other renewable) energy to levels exceeding 20 per cent of average demand could be facilitated with smart grid technology, capable of balancing demand with intermittent sources of generation.
Solar PV is a low carbon energy source, with present day PV technology incurring less than 10 per cent of the emissions per unit of electricity power than fossil fuel based generation. The target of 20 GWp solar PV installed in the UK by 2020 could reduce electricity related carbon emissions by 7 per cent. For every GWp installed, this equates to avoiding 500,000 tons of carbon dioxide emissions per year.
Historically, solar modules were extremely expensive to install. Financial incentives such as feed-in tariffs were necessary to encourage people to set up PV panels. Recently, however, prices have begun to fall with the global growth in panel production.
The cost of setting up PV panels and connecting them to existing power systems is also decreasing. Currently, they contribute to half of the total system cost, but this is projected to decrease by 40 per cent over the next five years.
The UK government estimates that the price of solar-generated electricity will decrease by more a quarter before 2020, at which point it could be up to 10 per cent cheaper than power from coal-fired power plants. Solar PV systems are expected to become competitive with conventional power in other parts of Europe within a few years. The transition to solar power can be helped with incentive schemes that help to meet upfront costs of installing PV and guard against electricity price fluctuations in the future.
Developing new solar PV and related technologies can further reduce carbon emissions both by reducing costs and by broadening the range of applications for solar power. For example, different types of PV panel that are translucent, coloured, flexible or light could be used on building facades, windows and public spaces. Cheaper energy storage technologies would allow PV to be used more widely in off grid situations and for mobile power.
Research is also being done to manufacture PV technology more economically. Systems are being developed that are based on printable materials, which can churn out solar cells. This will lower costs and carbon emissions in the manufacturing process.
Meanwhile advances continue to be made in the associated technologies of installing panels, energy storage and grid integration. These kinds of emerging solar technologies will help to meet emissions reductions targets and fulfil the promise of low cost, widespread solar power – even in cloudy Britain.
Jenny Nelson is a professor of physics at Imperial College, London.
Jenny Nelson works for the Grantham Institute for Climate Change. She receives funding from the Engineering and Physical Sciences Research Council and the Royal Society. Christopher Emmott receives funding from the Grantham Institute for Climate Change and Climate-KIC. Ned Ekins-Daukes receives funding from Engineering & Physical Science Research Council, European Commission and the Office of Naval Research Global. Phil Sandwell receives funding from the Grantham Institute for Climate Change and Climate-KIC.