|Fig. 1: This diagram depicts a simplified model of a photovoltaic system. (Source: Wikimedia Commons)|
In Silicon Valley, the hub of modern technological innovation and development, access to electricity is often taken for granted and an afterthought in many peoples lives. However, the issue of lack of access to reliable electricity sources is a prominent issue across the world, with more than 1.3 billion people, or one-fifth of the world's population, living without access to electricity and another 1 billion people having unreliable access to grid power.  The majority of the world population that are without access to electricity are predominantly in rural regions and underdeveloped countries across the world, such as Cambodia.
Approximately 10.6 million people out of the 15.3 million population, or 80% of the total population of Cambodia, live in rural areas of the country.  However, only an estimated 24% of the country is electrified, or has access to a reliable source of electricity, with a large skew of the electrification being in larger towns and cities. Only 11% of the rural population have access to electrical grid power. 
In an attempt to address rural electrification, the Royal Government of Cambodia developed a multi-decade plan: 
15% of rural electricity supply from solar and small hydropower by 2015.
100% of village electrification, including battery lighting, by 2020.
at least 70% of household electrification with grid connected quality electricity by 2030.
Within the past two decades, there has been a lot of attention to utilizing decentralized, renewable energy sources in the rural electrification efforts in Cambodia, such as biomass, hydroelectric, wind, and solar power generation.
The total electricity consumption increased by 22% from 3527 million kilowatt hours (kWh), or 12.7 billion joules (J), in 2012 to 4297 million kWh, or 15.5 billion J, in 2013.  The rapidly increasing rate of electrical power utilization in Cambodia demonstrates the increased need for electrification efforts to support the demand. The use of solar home systems, or stand-alone photovoltaic-storage energy systems, offer a possible cost-effective method of supplying power to rural off-grid households in Cambodia.
Photovoltaic cells produce electrical energy from light due to the photoelectric effect, with the solar cell as the energy generator in a PV system. The solar cells are essentially thin wafers of silicon that are connected in parallel and series circuit configurations to produce a solar panel, as shown in Fig 1. A charge controller controls the amount of electricity flowing through the system, regulating charging and preventing overcharging. The direct current produced from the solar cells is then stored in a battery as a useful source of electricity.  The electricity from the solar home systems can be used to power small household needs, such as home lighting, television sets, and refrigeration systems. Furthermore, solar home systems are an attractive option for power generation as they are environmentally friendly and do not emit gaseous and liquid pollutants, contrast to the burning of fossil fuels. 
Although solar home systems provide an option to address the electrification of rural Cambodia, there are many challenges and barriers to implementing the technology to increase electrification efforts. One of the largest challenges of implementing solar home systems is that the high investment cost of the technology is not affordable by the general population living in rural towns and villages of Cambodia. For example, one of the few solar home system retailers in Cambodia, Khmer Solar, sells an 85-watt solar home system for approximately $750 USD. This is roughly two times the per capita GDP.  A 50% import tariff on solar panels contributes to the incredibly high cost of the power generating systems, making solar home systems an infeasible option for low-income people.  The batteries used in the solar home systems are one of the most expensive components, yet have the shortest lifetime among the system components.  Thus, advancements to increase the lifetime of the batteries, while maintaining the quality and decreasing the costs are currently being investigated.
Access to electricity can improve the wellbeing and lifestyle of people by increasing to their access to health, education, welfare, and technology.  Solar home systems are available as a feasible option to the electrification of Cambodia. However, technological and economic advancements are necessary to overcome the current barriers to broad utilization of solar home systems to provide energy for rural regions of Cambodia.
© Davis Chhoa. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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