"High energy prices and the quest for security of supply will give home storage batteries a further push in 2022," BVES said on Wednesday, presenting an industry-commissioned study undertaken by 3Energie Consulting.

Household power battery unit sales could rise by 67% this year from 430,000 at the end of 2021, the report said.

As of April, that number has already grown to 500,000, representing 2.5 gigawatts (GW) of capacity, equivalent to one or two big nuclear power stations.

The number of units for the end of 2021, mostly installed in houses with rooftop solar power generation, was up by 145,000, or 50%, from 2020, and is 14 times the number in 2015.

Germany counts 2.2 million solar photovoltaic systems which produce power at home. Before residential batteries were available, the electricity produced went exclusively to the grid.

Now, more and more people are buying batteries as they become cheaper and bigger, spurred further by a quest for self-reliance amid spiralling energy bills.

Householders, typically families with detached houses, have been upgrading their homes to store surplus power for general use and, increasingly, to fuel electric cars and heat pumps.

Leading home-battery vendors in Germany include domestic players Senec, sonnen, owned by Shell, and E3/DC, and foreign players such as LG Chem and Tesla.

Overall sales by the storage industry represented by BVES rose 29% last year to 8.9 billion euros ($9.7 billion), and may rise again by that percentage in 2022, 3Energie said, adding that the potential was uncertain.

Still, there were some hindrances to sales in the shape of logistics and supply-chain bottlenecks, which had led to shortages of raw materials and components, and the availability of qualified labour was tight.

Home-storage batteries for power and heat accounted for 4.4 billion euros of total turnover, which included pumped storage plants and grid size batteries to help power stations and industrial energy consumers regulate power supply flows.

($1 = 0.9170 euros)

(Reporting by Vera Eckert; Editing by Bernadette Baum)