Off-grid Solar Solutions Without Backup Batteries

There continues to be ground breaking technology research in the area of off-grid solar products. Germany’s Fraunhofer Institute has developed an off-grid solar solution to maximize utility of power supply while minimizing the need for storage solutions. In rural areas and in developing countries the potential for off-grid solar applications is great. However, the initial costs can prove to be an impediment to more widespread usage.

Researchers at the Fraunhofer Institute for Solar Energy Systems have developed an energy management system which optimizes the use of electricity produced by a concentrated off-grid solar system therefore getting around the need for expensive batteries.

Working on a model project on a farm in Upper Egypt, a concentrated off-grid installation was installed to power irrigation systems, which pump water from deep wells. The CSP installation also requires power to track the sun’s movement, optimizing the solar light yield.

The Fraunhofer energy management system monitors the amount of energy produced and then ensures that it is delivered to the devices that need it most. “By immediately using the largest share of the energy that is generated we can save on expensive storage media capacities,” said Alexander Schies from the Fraunhofer ISE.

To illustrate, the submersible pump, which is 105 feet deep, can be powered to fill the reservoir when energy is available and the irrigation pump or desalination unit at other times. Only a relatively small battery is needed to ensure the off-grid solar tracker and measuring system remains powered. “We need this reserve, in particular, to align the CPV modules in the morning to their morning position,“ explains Schies’ colleague Jakob Wachtel.

Technically all the components of the irrigation system have micro-controllers, to inform the energy management system as to their status. A Universal Energy Supply Digital Protocol was developed at the ISE to facilitate this communication and the communication of energy levels also.

The USEP is being integrated into the CANopen protocol, which is commonly used in automation technology. “All systems that work with these kinds of protocols can be expanded at any time with devices that ‘understand’ CANopen or UESP completely independent of the manufacturer. This is practical if a defective component has to be replaced,” said Schies. This allows for further system savings with the off-grid solar system and simplifies maintenance.

Source PV Magazine