* To increase number of shares outstanding by up to 19 pct
(Adds details, graphic)

By James Topham

TOKYO, Sept 29 (Reuters) - Tokyo Electric Power Company
(TEPCO) said it will raise up to $6.6 billion in the largest
share offering by a non-financial firm this year to fund the
construction of low-carbon energy units and invest overseas.

TEPCO had announced plans earlier this month to bolster its
renewable and nuclear energy operations and to expand its
business in Asia, as it faces rising pressure to cut greenhouse
gas emissions and shrinking demand at home.

It earmarked 2.5 trillion yen ($29.83 billion) for investment
in low-carbon projects such as nuclear power plants, liquid
natural gas units and the development of a smart power grid, as
well as up to 1 trillion yen in growth areas, mostly overseas.

The reports of TEPCO's first new share issue in 29 years had
sent its stock tumbling 7.8 percent to 2,105 yen, the biggest one
day drop in nearly 2 years. Volume spiked to 32 million shares,
more than 10 times the daily average over the past 3 months.

The company said on Wednesday it will issue up to 254 million
new shares to raise up to 555 billion yen, following earlier
media reports that it was looking to raise several hundred
billion yen. The announcement came after the close of trade.

The issue could increase the amount of shares outstanding by
about percent.

"From a returns-based approach, or a capital-based approach,
it is very difficult to make an arguement for the timing or
rational for this," said Penn Bowers, an analyst at CLSA
Asia-Pacific Markets in Tokyo, commenting before the official
announcement of the share sale.

"I'm surprised they feel the need to procure particularly
this amount early on, most of their nuclear build is the second
half of the decade in terms of requirements and some of those may
eventually be delayed," Bowers said.

Japanese non-financial companies have raised 1.66 trillion
yen from the equity markets so far this year, twice as much as
the same period a year ago, Thomson Reuters data shows.

TEPCO's capital raising is set to be the largest by a
non-financial Japanese firm this year, trumping a 542 billion yen
share offering by oil and gas explorer Inpex Corp in July.

Nomura Securities is the lead underwriter for the TEPCO share
(Additional reporting by Nobuhiro Kuko, Junko Fujita, Taiga
Uranaka; Editing by Nathan Layne)