Next generation solar technologies

Next generation solar technologies

Solar technology fights to wean itself from government support  Recent policy changes by governments around the world show that renewable power sources cannot rely on attractive feed-in tariffs and subsidies for ever and they need to become more efficient and competitive.
Solar is making strides towards the increased efficiency that will give it parity with conventional forms of power generation.  That is certainly an achievable aim in the medium-term and next generation solar technologies will help.

Silicon still represents the main cost of photovoltaic (PV) cells. As silicon is also used in semiconductors for computers and consumer goods, overall demand for the material is going to affect its price and availability for use in solar. Thus, using less silicon to generate the same amount of power or finding an alternative material would make solar more competitive and even expand the potential market.
Also, according to the US government’s SunShot initiative reducing the installed cost of solar energy systems by 75% will spark large scale adoption of the technology in the US.

It is for this reason that in September US Energy Secretary Steven Chu announced $145m of grants for next generation solar technologies that will improve efficiency and reduce costs.
Efficiency covers the solar efficiency of cells in terms of the energy they can produce, but also the efficient use of materials and reducing costs. Hence, solar efficiency tends to be thought of in technical terms but less thermally efficient technologies could still produce power at a lower overall cost as well.

One such technology is concentrated solar power (CSP) technology, which consists of using mirrors to focus sunlight onto water, which produces steam that in turn powers turbines that generate electricity. This contrasts with PV solar, which turns the sunlight directly into electricity. CSP does not use scarce materials but it requires an enormous site and significant capital spending. It used to be cheaper in terms of the cost of power generated than PV but the fall in the price of PV cells has changed that.

However, Hawaii-based Sopogy is developing Micro-scaled CSP (MicroCSP), which enables much smaller-scale installations that can be placed on a roof. The technology can stabilise energy production in cloudy conditions and prolong production after sunset. Sopogy has signed a memorandum of understanding with Chinese property and construction company Sichuan Dongjia Investment Company, which will open up the Chinese market to its technology.

On the other hand, Massachusetts-based solar technology firm 1366 Technologies believes that manufacturing improvements can further reduce the cost of silicon PV and cut costs by 10% a year up until 2020.
Nanotechnology is one way to improve efficiency. Earlier this year, DuPont acquired California-based Innovalight, which has developed an ink that contains silicon quantum dots. This ink is applied to cells during the manufacturing process and enables them to capture a broader spectrum of light. This means that the cells could achieve efficiency levels of up to 19% and it can be used with thin film technology thereby reducing materials usage.

Another way to achieve those necessary cost reductions is by employing thin film solar, which uses much less silicon than conventional solar, helping to reduce the cost. Typically, thin film solar uses 1% of material to generate the same output. The cells can be more flexible, both literally and in terms of their potential use. They can be wrapped around a building or even integrated in its structure. 
Thin film solar can use silicon or other materials used in the semiconductor sector. Copper indium gallium selenide (CIGS) and cadmium telluride are two alternatives. CIGS performs better in low light and in low-angle conditions and it is also estimated that production costs can be lower than any silicon alternative and less than half those of monocrystalline silicon. 

One drawback of alternative solar technologies, such as thin film PV, is that solar efficiency is lower, although it is expected to move towards the level achieved by conventional solar over the coming years. The solar efficiency of conventional solar is typically between 16%-18%, although some firms claim 20% or more for their technology. 
Berlin-based research institute Sulfurcell believes that within the next year it can scale up production of its thin film CIGS cells and achieve 14% efficiency. Even so, the lower materials usage could make thin film more cost effective.

Efficiency improvements and cost reductions will benefit CSP and PV. According to GTM Research, the cost of PV-based solar power is likely to halve to $0.07-$0.08/kWh by 2020, whereas the CSP-based cost will halve to just over $0.10/kWh. 
In any case, when compared to many conventional power generation technologies solar is still in its infancy and further R&D investment is likely to further greatly reduce the costs of the energy it produces.