* 16,000 solar panels on tunnel power Belgian trains
* Panels produce 3.3 GWh of electricity a year
SCHOTEN, Belgium, Aug 12 (Reuters) - Trains already have a reputation for being a very clean form of transport but Belgian commuters can now boast railways which are partially powered by solar energy.
A public-private consortium consisting of Belgian rail management company Infrabel and solar developer Enfinity has installed 16,000 solar panels on the roof of a 3.4 km (2.1 miles) long tunnel between Antwerp and the Dutch border, creating enough electricity to power 4,000 trains a year.
The unique feature of the project, which is designed to produce 3.3 gigawatt hours a year, is that the energy produced does not flow into the national grid but is used directly by the trains.
Enfinity says that by cutting out the middle man, the grid operator, it can offer electricity about 30 percent cheaper.
Infrabel benefits from being able to sell cheaper electricity to its customers, which include the Belgian railways and private high-speed operator Thalys.
Enfinity and the other investors, such as the councils of the towns of Brasschaat and Schoten which border the tunnel, expect to see a return on their joint investment of 15.7 million euros ($22.12 million) within nine years.
Enfinity says the solar panels used in the project are made by Chinese company Jinko Solar , which it said offered better returns than European competitors.
In terms of sunshine, the summer of 2011 has so far been a disappointing one, even by Belgian standards, with 20 days of rain in July and eight days of misery so far in August according to the Belgian Royal Meteorological Institute.
Enfinity's marketing head Jurgen Van Damme told Reuters that bad weather was part of the calculation and that he still expected an average of 900 hours of sun each year.
"There are good wine years and there are good solar years," he said.
Infrabel said it was considering a project fuelled by wind power at another location in Belgium.
Passengers on a train entering the solar tunnel, which was inaugurated in June, reacted positively.
"We have solar panels at home so we know that it works and it's pleasant to see that we don't have to pay too much for electricity. So yes, I think it's a nice initiative," said passenger Els Krols on her way from Antwerp to the small town of Noorderkempen.
(Reporting by Robert-Jan Bartunek; additional reporting by Marine Hass, editing by Paul Casciato)
Created by Paul Casciato