Futurist and author Ray Kurzweil has theorized that solar power could cover all of the world’s electricity needs by the year 2031 if the PV market continues on its decades-long exponential growth path – essentially doubling every two years – even though energy from sunlight accounts for only about 1 percent of global grid power today.
But what about the considerable technical obstacles that still stand in the way of ubiquitous electricity from the sun?
Two new reports show how the dream of a solar-dominated power grid already is being converted into reality in select areas and make recommendations aimed at expanding solar power’s impact on grids around the globe.
Published this month by the International Energy Agency’s Photovoltaic Power System Programme (IEA PVPS), the study High Penetration of PV in Local Distribution Grids presents a collection of case studies that highlight “technically effective and economically efficient solutions” for integrating large volumes of solar power into local electricity networks.
“The massive deployment of grid-connected PV in recent years has brought PV penetration in the electricity grids to levels where the conventional fit-and-forget approach to interconnecting PV reaches its limits,” according to authors Roland Bründlinger and Christoph Mayr of the Austrian Institute of Technology.
“In many cases, constraints and limitations of [the] existing electricity infrastructure already have evolved [into] one of the key barriers delaying or impeding the realization of PV projects.”
The report explores experiences and outlines lessons learned from the adoption of solar power in 11 countries – Australia, Austria, Belgium, China, Germany, Greece, Italy, Japan, Spain, Switzerland and the United States.
On a nationwide basis, PV’s share of total electricity consumption in these countries ranges from less than 1 percent (Austria, China, Japan) to approximately 6 percent (Germany and Italy). But in certain regions, much higher percentages are being reached – especially during periods of peak solar production.
For example, peak PV generation accounts for 34 percent of demand on Australia’s Magnetic Island, off the northern coast of Queensland, which has a peak load of 5 MW. PV even covers 75 percent of demand on one particular distribution transformer on the island. The Greek island of Crete provides another example of high-PV grid penetration, but on a larger scale. Wind and solar combined sometimes account for up to 60 percent of Crete’s power supply.
The case studies feature best practices for dealing with such large percentages of PV and other renewable energy resources on the grid. Many of the case studies show, for example, how the control capabilities of modern power inverters can assist system planning and operation.
Recommendations for ‘change of paradigm’
And accompanying report Transition from Uni-Directional to Bi-Directional Distribution Grids presents the IEA program management’s recommendations for transforming grids designed for one-way power flow into more dynamic networks capable of distributing power both to and from solar-powered homes and businesses.
“The increasing occurrence of reverse power flows coupled to a decrease of the prices and volumes at which conventional generators can trade their production on power markets lead to a change of paradigm for the operation of power systems,” wrote the report’s authors from the European Photovoltaic Industry Association and Germany’s Fraunhofer Institute for Wind Energy and Energy System Technology.
“It also illustrates that although significant PV capacities have been interconnected to power systems in some countries, they are still not sufficiently embedded into the overall power system operation to guarantee a secure and reliable grid operation under the absence of conventional power plants. While PV is becoming a mainstream source of electricity, further improvement on PV system integration is required.”
The report stresses the importance of aligning network codes and laws with expectations of high national PV penetration scenarios – if nations have these – and recommends particular focus on the “frequency support mechanism provided by PV inverters” and “remote control interfaces from an early penetration stage on.”
Other recommendations focus on the “autonomous reactive power capabilities” of smart inverters “to increase the hosting capability of distribution grids for additional PV capacity.”
While PV plants are technically capable of providing a wide range of such ancillary services – including frequency control, voltage support, grid management, and black start – the report also notes, “Often, the transition from one penetration stage to another becomes possible only by overcoming certain regulatory barriers, which hampered further PV deployment in the past.”
Maybe his explains why IEA currently targets meeting only 16 percent of global electricity demand with PV in 2050. That’s much less aggressive than the futurist Kurzweil theorizes is possible, but perhaps also much more realistic.
Electric grid photo CC-licensed by James Wheeler on Flickr.