“Imagine that you have access to energy storage at home. On days when the sun shines, you fill up with electricity from your solar cells. At night, you replenish the energy storage from the grid when electricity prices are lowest,” says Björn Jernström, President of Ferroamp Electronik AB.“Our energy storage system has a host of smart features that allow the stored energy to be used during the hours of the day when purchased electricity costs the most – like when we wash, cook, watch TV or sit in front of the computer.”
“Our product is called Smart Energy Hub and Power Conditioning (Current Equalizing Technology) is one of its features. With the help of the hub, you can use electricity when you need it most. To fry meatballs and wash clothes in the middle of the night is not suitable for most people and here we offer an interesting and environmentally sound solution, “says Jernström.
From DC to AC, and vice versa
For the energy from a solar facility to be utilized in a home, DC power needs to be converted to AC. This is done by means of a current converter. Ferroamp replaces a traditional converter with a bidirectional converter that not only converts DC power from a solar array into AC but also converts AC power from the grid to DC power. The DC current is needed to charge a battery but currently the interface to the battery is not fully developed. “We are now developing a battery management system with cell balancing to handle lithium-ion batteries,” says Jernström. “We are doing this because there are no ready-made solutions at a realistic price that can handle such high voltages. These are in the 350 Volt range.”
The company has developed a prototype that shows that several functions work and several patent applications have been submitted. One of the applications is based on power levelling. In practice, this means that energy can be transferred from one phase conductor to another and through this three-phase connection can be utilized more efficiently.
The main fuse in a home can thus be reduced in size, but the system can also be used to increase the load on the network. The latter is particularly interesting if in the future we will need to charge an electric car from the wall socket.
The technology to control and regulate the power supply is the subject of another patent application. In some countries there have been significant problems with frequency and voltage regulation of the power supply when connecting large amounts of electricity from solar cells. Features in Ferroamp’s converters allow them to improve the balance of power when renewable energy is used.
According to Jernström, the Energy Hub system has many advantages:
- The system independently and automatically controls energy flows between the solar cells, energy storage, the power grid and local consumption. The intention is that the economic benefit is maximized for the consumer.
- If there is a power failure, refrigerators or other major appliances can continue to receive electricity.
- The system is controlled by information including current electricity prices, weather, the status of energy storage, local consumption and other factors. For example, the electricity market knows one day in advance what the price of electricity will be for the coming days. The smart energy hub utilizes the knowledge of when electricity prices are lowest, and stores energy at these times.
It is a modular system consisting of two units whose size is comparable to a microwave. There is a converter and a battery pack. Production will initially take place in Sweden, but cost-effectiveness will control production locations in the future. There remains a lot of development, prototype and testing work to do.
Profitable for the consumer
Sunny days yield an excess of solar energy. Consumers can now sell this excess electricity on the grid. With the Energy Hub, the excess is stored and Ferroamp has worked out the finances for an ordinary house.
“According to our calculations, selling excess energy from solar cells is equivalent to about 100 ore per kWh, but you only get 30-40 ore per kWh when selling the surplus,” says Jernström.
“But if you can bring home and store cheap electricity at night, the calculations become even better. Compared to purchasing a solar system today, you would, if its converter were replaced with our Energy Hub, cut the payback period for the facility in half. The biggest savings would come from reduced network charges, if one is connected to an electricity network that have them. There is definitely an economic argument for our product, “says Jernström.
This article was published in December 2012