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04 Floating solar testbed at Tengeh Reservoir.
05 Researchers working in the state-of-the-art silicon cell
laboratory at SERIS.
05
Preparing for a
Solar-Ready Singapore
Solar energy is the most viable renewable energy resource in Singapore. However, deploying solar energy on a large-scale presents its own set of challenges. Solar energy is inherently variable because of clouds, and does not work nearly as well when the sun is not shining. For Singapore, this problem is compounded by the seemingly chaotic and considerable cloud formation and movements in the tropics. This results in abrupt and significant changes in available sunlight which makes forecasting a highly complex problem to tackle. To put things into perspective, sensors deployed by SERIS across Singapore have shown that solar power generation for the whole island can be reduced by up to 88% within an hour due to large convective clouds. Thankfully, dips of this magnitude are relatively rare events. Nonetheless, accurate forecasting at several different time-scales will be vital in an era of high solar energy penetration because this affects how efficiently the power system operators can schedule power dispatch, and how quickly they can respond to future cloud-induced
changes in solar energy output. This issue of variability could be partly mitigated by deploying energy storage systems. These systems are able to store energy from solar arrays during times of excess generation and inject power into the grid on demand, and so offer an alternative way for power system operators to ensure a reliable supply of electricity. The Energy Market Authority (EMA) is currently exploring both forecasting and energy storage as ways to build a more dynamic energy landscape for Singapore that can accommodate an increasingly significant proportion of solar power. Under a grant from the EMA, SERIS is collaborating with a consortium of research partners to develop more advanced capabilities for forecasting solar irradiance to help enhance grid operations. The EMA is also working towards an energy storage deployment target of 200 MW beyond 2025. Additionally, the conventional power grid topologies and energy markets are not particularly adapted to incorporate a high degree of distributed energy sources such as solar. Grids today are typically built in a “top-down” arrangement, in which electricity flows downstream from big
thermal power plants through transmission lines into smaller distribution networks. In this arrangement, it is clear which entities are generators, distributors and consumers of electricity. However, in a liberalised electricity market like Singapore, new entrants, such as the owners of rooftop solar systems, should also be allowed to participate in the market. These smaller systems are connected to buildings at the distribution level, which can act as either consumers or generators of electricity depending on the time-of-day and internal power needs. The challenge, then, is to have an adequate framework in place to allow these distributed solar energy systems to participate in the electricity market without jeopardising the security and reliability of the grid, and to sell their “green” electricity fairly and reliably.
A long-term challenge for Singapore is in the end-of-life management for solar panels. Like all electronic products, solar panels have finite lifespans. Once Singapore hits its solar deployment target of 2 GWp, there would be millions of solar panels deployed all across the island. Considering that most systems are still relatively new
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