Germany needs green energy master plan -study
* Shif in power systems to cost 335 billion euros
* Difficult cash calculations deter investors
* If doesn't act fast, Germany might turn net importer
FRANKFURT, June 25 (Reuters) - Germany needs a master plan that brings together central and local government policy and provides certainty for investors and project firms if it is to find the $420 billion needed to fund a radical shift towards green power, a study said on Monday.
HypoVereinsbank (HVB), a unit of Italy's UniCredit , put the cost of what Germans call the "energy U-turn" - its move to switch off nuclear plants, increase wind and solar power generation and improve power grids - at 335 billion euros ($420 billion).
Europe's biggest economy needs substantial investment to build up renewable capacity and connect it with the nine countries on its borders, it said.
Investments in plant and infrastructure would amount to 85 billion, while 250 billion would be needed for support payments to renewable energies, the study estimated.
"In core areas of the energy U-turn, project financing is currently only possible to a limited extent, because revenue and expenditure cannot be sufficiently gauged," HVB board member Lutz Diederichs said in a statement.
"This makes the calculation of cash for the projects difficult," he added.
By 2020, 35 percent of all Germany's electricity is meant to come from renewable resources, compared with 20 percent now.
Germany also has decided to phase out of nuclear power completely by 2022, faster than originally planned, in the wake of the Fukushima nuclear disaster. The reactors had provided 23 percent of its power supply in 2010.
The HVB study, done jointly with the HWWI economic research institute in Hamburg, said a master plan was needed to bring together central government and state strategies, to ensure the integration of new power sources and to clarify the jobs to be undertaken by private versus public partners.
One obstacle to obtaining financing for renewable projects is that income from wind and solar can be unpredictable because it relies on weather.
For offshore wind farms in particular, questions also remain over liabilities for technical problems and maintenance as well as the lack of cable connections to onshore grids.
HVB recommended that some mechanism be found to stabilise cash flows from projects that account for at least half of the overall investment volume.
HVB said new international banking rules, dubbed Basel III, would make lending to renewable energy and grid projects, which tend to be for the long term and involve high risk, even more difficult and expensive.
Basel III requires banks to improve their risk-management systems and hold more capital as a safety buffer in case of economic or financial downturn, raising the bar for outlays on uncertain risks.
HVB recommended that banks, as well as making loans, should act as intermediaries to help raise funding from investors for projects.
"A successful implementation also hinges on acceptance by the population. So far, there are big discrepancies between the public perception and the realities of the energy shift," Michael Braeuninger, lead author at the HWWI, said.
The authors were also concerned about the need for speed in creating storage for power and in building up transmission networks in time to prevent Germany from having to import more power. ($1 = 0.7977 euros) (Reporting by Vera Eckert, additional reporting by Jonathan Gould, editing by Jane Baird)