One out of two German small PV plants built with storage in 2015

Almost half of Germany's small PV plants installed last year incorporated a storage system, while lithium-ion batteries are pushing lead-acid based units out of the market.

Between May 2013 and January 2016, 34,000 solar storage systems with a combined capacity of more than 200MW were grid-connected, according to a report by the RWTH Aachen University and the iSEA institute, for power converter technology and electrical drives, with funding by the German government, which supports solar storage investments via its KfW development bank.

"Solar storage systems within the shortest time have developed from a partially hand-made niche product into a mass market," the report says, adding that the KfW support has a positive impact on the entire market.

"The final consumer prices of solar storage systems still are high, but are falling fast," the scientists conclude, pointing to an 18% average annual degression in the price of li-ion systems and 5% for lead-acid systems.

As a consequence, li-ion is becoming the dominant technology for small-scale solar storage. In the last quarter of 2015, more than 90% of solar storage systems installed were li-ion-based, up from around 50% in mid-2014, the report finds.

Further price cuts are expected due to the entry of several large car companies in the storage market.

Top storage system manufacturers currently offer final sales prices of €1,000-1,200 ($895-1,075) per kWh of storage capacity. The report also expects new products with adjusted prices to be presented at the Intersolar fair in Munich next month.

Despite elevated media attention, battery systems by US electronic carmaker Tesla have not gained significant market share in Germany, where the top sellers are from local producers Deutsche Energieversorgung (brand name Senec), Sonnen, SMA and E3/DC.

A down-sized German storage scheme that started in March supports the purchase of grid-compatible PV batteries, initially with €500/kW of capacity. Overall support granted initially is capped at 25% of all costs that are eligible for aid, and will then gradually go down to 10% of that value towards the end of 2018.