• • • SURGE & CIRCUIT PROTECTION • • •
Increasing the efficiency of solar power
Solar power is currently the UK’s third largest renewable energy generator, but inefficiency challenges its growth. Here, Simone Bruckner, managing director of power resistor manufacturer Cressall, explores how solar panel efficiency can be improved to increase its supply to the grid
S
olar photovoltaic (PV) systems offer many power advantages; they’re easy and quick to install, scalable and can be deployed in a variety of locations. Solar PV systems can be installed in large solar farms, as well as residential and commercial buildings. Once installed, its fuel for generation, the sun’s energy, is free. However, solar PV systems aren’t consistently efficient, with many hardly surpassing 20 per cent efficiency. This productivity is low compared to wind turbines, which can have efficiency of between 30 to 50 per cent. Increasing the capability of solar PV systems is essential if we’re to incorporate more solar energy into the grid.
CHASING THE SUN
An existing method that can boost the yield of solar panels is solar tracking. Solar tracking systems move panels so that they are always directly orien- tated to the sun for maximum efficiency. This way, the panels generate a more consistent flow of en- ergy, without dramatically peaking at high sun- shine points such as midday or in summer. The systems can be used in ground-mounted solar panels, such as solar farms for large-scale commercial or utility projects. The movements can be controlled by a pre-programmed path based on
14 ELECTRICAL ENGINEERING • MAY 2021
astronomic predictions, or they can use solar radiation sensors to detect and react to the sun’s live position. The tracking system can be single axis or dual axis.
Single axis systems move the panels through only one plane, usually from north to south to track the sun rise and set. Dual axis systems can move in this direction, but also in another plane, making them bidirectional. This allows the solar panels to also be tilted from east to west to account for seasonal variations in the sun’s angle relative to the panel’s position on Earth.
Solar trackers can increase average solar panel power output by up to 35 per cent, and efficiency can be maximised by incorporating a dynamic braking resistor. Tracking systems use electric motors to alter their position. Here, braking resistors can ensure that the panels stop moving when required by dissipating excess voltage generated by the decelerating motor. This ensures the panel doesn’t overshoot its movement and land in a sub-optimal orientation to the sun.
RESISTING OVERLOAD
Maintaining solar panels’ condition also plays a vital role in their efficiency. Here, resistors can
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also be used when installing solar panels or dis- connecting them for maintenance. Regardless of whether solar panels are connected to the grid, they continue to generate electricity. Here, dummy load resistors can dissipate excess generated en- ergy into the environment as heat to prevent the solar panel from becoming overloaded. Damage from overloading can lower the running efficiency of the solar PV system.
Cressall has over 100 years’ experience in electrical engineering, and supplies solutions to the solar power industry. Our wide range of high- power dummy load banks are suitable for solar PV systems and can meet low noise requirements. We also supply dynamic braking systems for tracking systems to accurately orientate solar PV panels to the sun, and put any wasted braking energy back into the system to maximise efficiency. Solar tracking systems, along with dynamic braking systems and dummy load bank resistors, can improve solar panel efficiency and support future innovations — helping to incorporate more renewable solar energy into the grid.
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