| MONITOR | 2/2017 28 This large photovoltaic power plant was built so that the minus pole of the PV battery was function- ally earthed against ground. Functional earthing is preferred when degradation of PV modules via the PID effect 1) is to be prevented. Functional earthing is achieved using a GFDI – a switch which breaks this earthing in the event of an overcurrent due to a first fault and subsequently leaves the PV battery unearthed. In the past, fires often occurred when using large, functionally earthed PV batteries despite the use of a GFDI. Therefore, the standard NEC 2014 now requires insulation monitoring for the direct cur- rent part of PV systems (PV batteries) in section 690.5 “Ground-Fault Protection”. Insulation monitoring is performed periodically when- ever functional earthing is not ensured by the GFDI. Frequently, insulation monitoring is performed in the morning before the PV system is started. (Also see: Rebekah Hren, Brian Mehalic: Understanding the NEC 2014 and Its Impact on PV Systems: Page 3 of 12, Section 690.5 “Ground- Fault Protection”. In SolarPro magazine Issue 7.3, Apr/May '14) In order to ensure the electricity supply to their new “Cerro Negro Norte” plant, a mountain surface mine 42 km east of the city of Caldera, the CAP Group plan- ned the construction of one of the largest photovoltaic power plants in Latin America in Copiapó, in the heart of the Atacama Desert. The North American company SunEdison was chosen as a partner for this project. SunEdison is a world leader in the field of photovol- taic and semiconductor technology and is one of the largest suppliers of innovative solar energy solutions. With the development, financing, operation, and moni- toring of solar plants in more than 35 countries on five continents, SunEdison runs over 1,000 photovoltaic power plants with a total production of 5 GW (as of 31 July 2015). The “Amanecer Solar CAP” in Chile has more than 310,000 photovoltaic modules spread over an area of 250 hectares. It was constructed in just six months and was commissioned in May 2014. The energy generated runs into the largest integrated grid in Chile, the SIC (Sistema Interconectado Central). With an investment of USD 250 million and an installed capacity of 100 MWp, the PV power plant produces 370 GWh of clean energy every year and reduces CO2 emissions by approx. 135,000 tonnes - enough energy to supply 125,000 households every year. The energy produced is approximately 15 % of the CAP Group’s yearly consumption. This also means that the Group saves more than 71 million litres of fuel, which would be needed to create electrical energy if this plant did not exist. 1) PID (Potential Induced Degradation) is an effect which affects PV modules and leads to creeping loss of performances over years