Smart Home with Solar Electricity

It is an unprecedented success story – in only a few short years renewable energy sources have become an affordable and reliable source of clean electricity. According to preliminary numbers from the German Association of Energy and Water Industries, in the record month of May, for the first time Germany’s PV plants produced more than four billion kilowatt hours of CO₂-neutral electricity.  This almost equals the annual consumption of 900,000 average German households and represents an increase of approximately 40 percent over May of the previous year. In the context of sinking feed-in compensation and the discussion about grid relief and self-consumption the question becomes: How can we best use this electricity?

Self-consumption Makes Sense

The sun shines, and the rooftop PV plant produces clean electricity. Wouldn’t it make sense to use this electricity here and now in order to do the washing or clean the dishes?

Self-consumption of solar electricity creates independence and relieves the power distribution grids.

It would make sense – for a number of reasons: With self-consumption of solar electricity, plant operators have increased independence from energy suppliers and thus from potentially rising energy prices. Moreover, the self-produced energy is used more efficiently since no losses in transit arise. And finally, electricity consumed directly where it is generated also reduces grid loads, thereby avoiding grid expansion. Thus, as high a proportion of self-consumption as possible as a result of skillful energy management is the key to a decentralized energy supply from renewable sources.

Energy Management System Components

Successful energy management that makes sense in the “Smart Home” is based on three successive steps:
1) comprehensive analysis, forecasting and information, 2) automatic load controls and 3) the intermediate storage of energy. In short, the first step involves understanding the energetic circumstances so that they can be actively adapted in the second step, before being optimized in the third step. The most important components of the SMA Smart Home concept are the Sunny Home Manager, location-specific production forecasts via the Sunny Portal, and the flexible Sunny Backup system, which allows the intermediate storage of solar electricity while at the same time providing an electricity supply with grid-quality reliability. Furthermore, with the Sunny Boy 5000 Smart Energy SMA is developing a wall-mounted PV inverter with integrated battery – the first high-volume unit of this type.

How Does the Smart Home Function?

Intelligent energy management in the SMA Smart Home

Using existing and planned product solutions from SMA, the following system architecture results: The Sunny Home Manager is the central controller in the SMA Smart Home. It is connected through a communications system to the PV inverter Sunny Boy 5000 Smart Energy and to household appliances, whose use can be scheduled flexibly. Based on the production and consumption forecast, current output and the desires of the user, the Sunny Home Manager controls household appliances so that they use self-produced power whenever possible. It also controls the Sunny Boy 5000 Smart Energy, which can store some or all of the excess power produced in its integrated battery and thus limit feed-in. The stored current is available again as needed, such as in the evenings or at night, which further increases self-consumption. The Sunny Home Manager also creates optimized “timetables”, both for appliances and for the battery system. The Sunny Home Manager can be used via any online Internet browser and can be accessed on a PC or smartphone, whether at home or on the move.

Storage Included: The Sunny Boy 5000 Smart Energy

While increased self-consumption stagnates with larger storage capacity, the level of battery use is steadily decreasing. If a backup function is not needed, a smaller storage system is thus the more cost-effective choice.

Whereas larger storage systems can only be used to the fullest on days with a high yield, the only two kilowatt hour storage system of the Sunny Boy 5000 Smart Energy charges relatively quickly and increases the rate of self-consumption almost all year round by up to 50 percent*. The available charge/discharge cycles of the lithium-ion battery are used optimally, which reduces the specific storage costs. SMA introduced the device for the first time at this year’s Intersolar. It should be available in 2013.

* at an annual consumption of 4 900 kWh and 5 kWp power generation capacity

Intelligent Energy Management for the Electricity Supply of the Future

Load-oriented, grid-connected storage as part of Smart Homes is an important component of the energy transition: In Germany, more than 70 percent of the PV power comes from smaller PV plants which feed in to the low-voltage grid, where most power consumption occurs. A decentralized balance of generation capacity and power consumption uses the reduced distance between the power generator, load and storage system, and minimizes both transmission loss and grid load. The key lies in self-consumption using intelligent energy management systems and, based on this, decentralized storage, which is also integrated in these systems. Together they are the trailblazer for converting the electricity supply into a smart grid based on renewable energy.