The negotiations with China are expected to include setting a minimum price at which Chinese solar panel manufacturers can sell in the EU.
"During past days, both China and the EU have been holding communication, contact and consultation at all levels ... the bilateral talks are positive and constructive," Gao said.
China expects to end the negotiations and agree on a deal over the price by August 6, Gao added.
De Gucht said the Chinese and European negotiators started their discussions last week.
"All the European negotiators came to Beijing on Thursday, and were in meetings on Friday on the issue with a very clear view to coming to an amicable solution. So we continue to work on that," he said.
China and the EU have the sincerity to find solutions as quickly as possible, but there has been no breakthrough so far in the talks and such disputes are rarely resolved overnight, De Gucht said.
"As I have stated time and time again during the course of the investigation, the EU has only one wish — to find a negotiated settlement on the basis of 'undertakings' that can remove the injury caused by the dumping on our market. Nothing more, nothing less," De Gucht said.
If no settlement is reached during the negotiations, the average punitive tariff would rise to 47.6 percent from 11.8 percent, which means China's solar producers would be blocked outside the European market. In December, that rate would be put in force for five years.
Yao Ling, a researcher on China-EU relations at the Chinese Academy of International Trade and Economic Cooperation, a think tank, said: "The EU showed its intention to communicate with China when the bloc announced a dramatically reduced initial rate in early June, but more sincerity is needed during the talks otherwise both sides will be hurt by high tariffs.
"There is a possibility that the two sides will agree on the price by August, but the EU would have to make more compromises in the talks."
Tu Xinquan, deputy director of the China Institute for WTO Studies at the University of International Business and Economics in Beijing, is upbeat on a reasonable agreement on the price being reached by both sides in a few months.
"But the negotiations, and also the bargaining, will be very tough," Tu said.
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