Team explores integration of renewable energy devices

German researchers are hoping to make it easier to integrate different small-scale renewable energy devices in order to avoid intermittency problems.

A team at the Fraunhofer Institute for Solar Energy Systems (ISE) is developing a smart energy management system that allows components built by different manufacturers to communicate.

This could make it easier to build self-sufficient power generation systems that use different types of renewable energy devices — such as wind or solar — to ensure electricity is always flowing, even when one source isn’t available.

‘In order to make communication between the different components possible you need to have a standardised protocol,’ Jakob Wachtel from ISE told The Engineer.

‘There are a couple of companies that sell a complete system off the shelf but it’s difficult to provide a system for any application.

‘That’s why it makes sense to have a manufacturer-comprehensive standard that would make it possible for the system designer to use components of different manufacturers.’

The energy management system helps balance the demand for electricity with the supply from its different sources, which could include batteries or a diesel-powered generator if no other option is available.

The Fraunhofer team has built a model of how such a system might work at a site in Wadi El Natrun, Egypt, where it is used to draw well water to irrigate fields.

This system combines a concentrator photovoltaic (CPV) system with a tracking device to follow the movement of the sun, a small battery and a water pump.

The CPV modules power the pump and the tracking system, and the battery allows the tracker to return the solar panels to an east-facing position once the sun goes down, ready to start collecting energy again the next morning.

energy management
Standard protocols are needed to integrate different devices such as the solar panels, sun-tracking module and battery at Fraunhofer’s test site in Wadi El Natrun, Egypt

’This application has a lot of controllable loads so you can have very small-sized storage,’ said Wachtel.

’But there are other applications, for example, if you’re trying to electrify a village, where you don’t have so many controllable loads, because when someone wants to switch on a light they don’t want to wait for the sun to shine.’

The model uses embedded systems that act as gateways between the management system and the components but the aim is to replace this with a set of protocols that allow the central computer to immediately identify and communicate with any devices added.

The researchers are working with a number of electronics and energy manufacturers, including larger companies such as Panasonic and more specialist firms such as Steca, to develop its Universal Energy Supply Protocol.

They hope to integrate this into the existing CANopen international standard protocol for control systems and make it available as an application for grid-independent energy supply systems in the next two years.