* Acciona H1 core earnings down 18.2 percent, in line
* Core energy division also hit by slowdown in renewables
* Net profit rises fourfold on one-time gains, in line
* Conference call at 0100 GMT
(Adds comment on energy prices, quote from company, detail)
MADRID, July 28 (Reuters) - Spanish energy, construction and services group Acciona reported first half core earnings down by almost a fifth on Tuesday as its energy division suffered from lower power prices.
Earnings before interest taxes depreciation and amortisation (EBITDA), also affected by the absence of revenue from the company's stake in Endesa, sold earlier in the year, fell 18.2 percent to 393 million euros ($561.1 million), in line with analysts' forecast.
"The drop ... is mainly explained by the results in the energy division which was affected by the decline of the average pool price together with the activity slowdown of the wind industrial business," Acciona said in a presentation.
Earnings also fell at a real estate division and growth was lacklustre in construction, with both areas hit by Spain's property slump.
Net profit surged more than fourfold to 1.2 billion euros, in line with expectations thanks to capital gains from the Endesa stake sale.
Acciona is due to hold a conference call with analysts at 1000 GMT, where analysts are hoping for an optimistic outlook for the company's operating environment for the rest of the year. ($1=.7004 Euro) (Reporting by Jonathan Gleave; editing by Simon Jessop)