In the past year solar power in the UK has more than doubled while in the US it has grown by 30 per cent . But many current systems fail to solve the problem of how energy is managed and used overnight when the sun sets . Traditionally , energy gathered during the day is sent back to the grid , but this can prove costly if you need to buy it back - unless you have a smart battery that stores the excess energy in your home . Sonnenspeicher ( pictured ) uses a lithium iron phosphate battery to store energy harnessed by solar panels . This energy can be used throughout the day , and any excess is stored for when the sun goes down . Rather than selling this excess electricity back to the grid , homeowners can then use their stored supply for power . With this in mind , German firm Automatic Storage Device ( ASD ) and designer Wolfram Walter have created the Sonnenspeicher . It uses a lithium iron phosphate battery to store the energy harvested during the day by solar panels fitted to a roof . This energy is used throughout the day , and any excess is stored for when the sun goes down . Rather than selling this excess electricity to the grid , and potentially having to buy it back at a later date or time , homeowners can use this stored supply to power their home until the sun rises again . Sonnenspeicher features an intelligent management system that automatically controls the charging and discharging current , to make it easier to manage how much energy is being used . Sonnenspeicher features an intelligent management system that automatically controls the charging and discharging current , to make it easier to manage how much energy is being used . It additionally has a Sleep mode that ensures the storage system never runs low and will automatically go into standby when not in use . Although it is designed to be completely independent of the national power grid , it can equally be wired up in the case of emergency . For example , whenever there is energy in the battery available , the connection to the grid is locked . When this energy runs out , the Sonnenspeicher connects to the grid 'in a millisecond ' ASD Sonnenspeicher uses a lithium iron phosphate battery to store the energy harvested during the day by solar panels . This energy is used throughout the day , and any excess is stored for when the sun sets . Rather than selling this excess electricity to the grid , and potentially having to buy it back at a later date or time , homeowners can use this stored supply to power their home until the sun rises again . Sonnenspeicher features an intelligent management system that automatically controls the charging and discharging current , to make it easier to manage how much energy is being used . It additionally has a Sleep mode that ensures that the storage system never runs low and will automatically go into standby when its not being used to increase efficiency . The system comes in different sizes ranging from the Sonnenspeicher 300 , which is 4.8 kWh , to the Sonnenspeicher 600 at 8.06 kWh up to the 1000 model which offers 13.44 kWh . Prices start at €8,450 ( £6,170 ) . It additionally has a Sleep mode that ensures the storage system never runs low , and will automatically go into standby when its not being used to increase efficiency . And although it is designed to be completely independent of the national power grid , it can equally be wired up in the case of emergency . For example , whenever there is energy in the battery available , the connection to the grid is locked . When this energy runs out , the Sonnenspeicher connects to the grid 'in a millisecond ' . This switchover works the other way too . If a home is predominantly powered by the grid , the Sonnenspeicher will still store energy and instead act like a generator during a power cut . 'We wanted to create a storage system that makes you truly independent of the national power grid , that adequately supplies all of your household appliances at all times , and that remains efficient and trouble-free for at least 20 years , so that you can have the peace of mind that your investment really is worth every penny , ' said the firm . The system comes in different sizes ranging from the Sonnenspeicher 300 , which is 4.8 kWh , to the Sonnenspeicher 600 at 8.06 kWh up to the 1000 model which offers 13.44 kWh . Prices start at €8,450 ( £6,170 ) . The firm said an average home can save around €1,200 a year ( £876 ) , so it would still take around seven years to recoup the costs , but the system will last for 20 years .
Sonnenspeicher was designed by Wolfram Walter and German firm Wolfram Walter . Its lithium iron phosphate battery stores energy from solar panels . Cheapest model is €8,450 ( £6,170 ) , but it will save money on electricity bills . It also comes with 'intelligent management system ' that controls current .