48 n CLEAN ENERGY July/August 2023 www.drivesncontrols.com Solar photovoltaic (PV) generation will account for two-thirds of this year’s record-breaking 107GW increase in global renewable energy capacity, according to a recent report from the International Energy Agency. The global capacity for manufacturing solar PV systems is expected to more than double to 1,000GW by next year. Based on this trend, the world will have enough solar PV production capacity by 2030 to comfortably meet the level of annual demand needed to achieve net-zero by 2050, according to IEA projetions. The UK’s solar power plans are relatively modest, rising from around 15GW of capacity this year, up to 40–50GW by 2030 – a similar target to that for offshore wind power. The UK is aiming for 70GW of solar capacity by 2035. Solar PV generation is now one of the cheapest ways to generate electricity, especially (but not only) in sunnier parts of the world. Of course, PV plants only produce power during daylight, but can be combined with storage to make electricity available even when it is dark. Over the past decade, the cost of PV power has dropped by 85% from $0.381/kWh to $0.057/kWh. Over the same period, concentrating solar power systems have experienced a 68% decrease from $0.340/kWh to $0.108/kWh, while PV installation costs fell from $4,731/kW to $883/kW. The US Department of Energy projects that the cost of PV power could drop to $0.03/kWh by 2030. But if solar power is to take off as predicted and take advantage of these plummeting costs, a serious obstacle will need to be overcome. Building large-scale solar arrays is a time-consuming, labour-intensive and costly business, often in extremely unpleasant working conditions subject to extreme heat and dust and, in some parts of the world, hazards such as snakes and scorpions. Companies that erect solar farms are finding it increasingly difficult to recruit and retain people prepared to do this arduous work. The scale of the problem can be seen in the US where it has been estimated that solar installations will have to increase by 60% between 2022 and 2030 to meet the Biden administration’s target of 30% of electricity generation coming from solar power by then. To achieve this, an extra 700GW of installed capacity and nearly 900,000 new installation workers will be needed. This is a substantial increase from the 230,000 workers employed by the US solar industry in 2020. And already in 2021, 89% of US solar firms were reporting difficulties in recruiting suitable staff – and those that they did hire often did not stay long. Not surprisingly, several companies – most of them in the US – are now turning to automation and robotics technologies to make it easier, safer, faster and cheaper to build solar arrays. And this could mean that the power from solar farms could become even cheaper. Piling pressures The first step in building a solar array is usually the arduous task of installing the piles on which the panels will be mounted, and digging trenches for the cables that acrry power from the arrays. A Californian start-up called Built Robotics has come up with technologies to make these jobs easier and faster. The first is an automated trench-digging machine based on adapted versions of conventional excavators. The company’s Exosystem technology converts almost any excavator into a robotic machine that can dig trenches autonomously at speeds of up to 55 metres an hour. It uses GPS to dig the trenches to an accuracy of around 3cm. Obviously, allowing huge excavators to operate autonomously poses potential safety risks, so Built Robotics has incorporated eight layers of safety into its trenching system. These include on-board cameras and radar with 360degree vision. If they detect any obstacles, operations are stopped automatically. Other forms of safety include a virtual geofence barrier that keeps the excavator within a safe operating area, wireless and hardwired emergency-stops, and remote cloudbased monitoring that provides redundancy to ensure reliable operation in the field. Built Robotics claims that in more than 18,000 hours of operation, installing more than 2GW of PV capacity, its technology has not experienced a single robot-related safety incident. A second technology from the company is an automated pile-driving machine that carries up to 192 piles, together weighing about 10 tonnes, on board. It picks them up and then hammers them precisely into the ground to depths of more than 2m at a rate of 500 blows per minute. The robotic pile driver can operate around the clock, and is claimed to up to five times faster than traditional methods. While Built Robotics’ pile-driver uses conventional piles, another US company, called Ojjo, has come up with an alternative technology for mounting panels that needs only about half as much steel. Its Earth Truss system uses anchors that are screwed into the ground using separate software-controlled actuators for velocity and position. Ojjo says it uses “advanced motion control software”to achieve precise alignment of the truss structure to simplify the installation of solar tracker Photovoltaic prices have plummeted and solar farms are springing up around the world. But this progress could be hampered by a shortage of people prepared to undertake the arduous work of installing PV arrays. Robots and automation could be the answer, saving time, cutting costs and enhancing safety, while reducing the need for manual labour. Automation promises a bright future for solar farms
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