Networks Europe March/April 2019 - Page 47

GOING GREEN installation and are less complex since they don’t require a battery system. There are also no storage losses involved during the lifetime of the array. This type of system is suitable for telecom stations near cities or areas with reliable grid connection. It’s possible, however, to add a battery to store the excess generated power instead of releasing it to the grid. Standalone solar power systems These are solar power systems that are not connected to the utility grid and require a battery system to store the excess power produced. These systems may use an auxiliary power source apart from the PV array, such as wind or most commonly diesel generators. Such systems are called standalone hybrid systems. This is suitable for remote telecom stations. In order to perform an economic evaluation of grid- connected PV systems for use in telecom base stations, PVSYST software was used to get an estimate of the number of the photovoltaic cells and inverters required for several sizes of installation as well as the performance of a system in London. The specification of the solar module used in the experiment was as follows: Mono-crystalline PV cells, standard module design and 25-degree mounting (optimised angle for London latitude). With the simulation results, a calculation was made to get the estimate of the initial investment, payback time and CO2 savings for several PV systems. Initial cost for a 4kW grid connected system is £10,000, with a payback time of approximately 13 years and CO2 savings during the system lifetime (25 years) of around 35 tonnes; the same results for a 10kW grid-connected system are, £23,000, 13 years and 70 tonnes respectively. In locations with higher solar radiation, the payback time reduces as the same kW can be generated with a smaller panel area, thus reducing the initial cost. Where zero refrigeration is used for cooling the IT equipment, this allows a reduced total kW provision and again, smaller panel area and initial cost. It’s recommended to use a grid-connected system in areas with an adequate power supply since standalone systems are more complex than grid-connected ones due to the presence of battery systems in addition to the inverters. If the utility grid isn’t reliable, or non-existent in case of remote areas, a standalone PV system can be the solution. As adoption and investment in PV energy increases, this technology will continue to be improved. These improvements include more efficient PV cells and both battery and inverter efficiency and lifetime increases. While PV panels and components prices decrease, the use of solar power in the data centre industry will strengthen over time. Any attempt at reducing the carbon footprint is helpful and the use of solar energy, even starting on a small scale, installation of solar panels accomplishes this. n 47