SERC is collaborating with Chris Greacen of Palang Thai to develop a guidebook on the interconnection of mini-grids to national or regional electrical grids. Titled A Guidebook on Grid Interconnection and Islanded Operation of Mini-Grid Power Systems Up to 200 kW, the document addresses both technical and policy aspects of interconnection and is intended for energy policymakers, mini-grid operators, utility administrators and engineers, and community leaders. Worldwide, more than 50 million households get their electricity from renewable energy mini-grids powered by small hydroelectric generators, wind turbines, or solar photovoltaic arrays. These systems provide clean, reliable electricity to rural locations not yet served by national or regional electric grids. They may be developed by traditional utilities or, more commonly, by private-sector developers.
When a national grid reaches areas previously served by isolated mini-grids, operators are faced with several challenges. Will customers served by the mini-grid be connected to the main grid? If so, what happens to the mini-grid’s generator, power lines, and other equipment? Will these assets be abandoned, or will the generator become another power plant selling electricity to the grid? If the mini-grid system remains independent from the grid, how can the operator keep electricity prices competitive?
If there is no policy in place to address these issues, mini-grid developers may be reluctant to invest in new projects and may use substandard wiring and undersized equipment to reduce costs, knowing that their investment could be made worthless at any time if the national grid arrives. These problems plagued mini-grid systems in Cambodia until the government developed a policy to allow mini-grid operators to become small power distributors (SPDs) and resell electricity from the grid. Since these regulations were instituted, over 100 isolated mini-grids have been converted to SPDs. Other developing countries with interconnection policies include Thailand and Tanzania.
The interconnection guide discusses technical topics, including voltage and frequency control methods and protective relays, as well as mini-grid policies from developed and developing countries around the world. A draft version of the guidebook is currently being reviewed by outside experts, and final publication is tentatively slated for early February 2013. The guidebook is being developed for Lawrence Berkeley National Laboratories under the auspices of the US Department of Energy’s Global Lighting and Energy Access Partnership (Global LEAP). This program is associated with the Clean Energy Ministerial, a global forum promoting clean energy policies and programs.