For the solar industry in Pennsylvania, Wednesday is a day of envy.

At 10 a.m., Delaware Gov. Jack Markell is to sign a legislative measure boosting his state's commitment to alternative energy, including a promise to get 3.5 percent of its electricity from the sun by 2025.

It is the sort of event solar installers had hoped to be celebrating by now - in Pennsylvania.

Those ambitions fizzled, however, when the legislature recessed right after passing the state budget on July 3, effectively killing any chance this year for adoption of the long-debated House Bill 2405.

That legislation would have upped the state's obligation to use a variety of clean-energy options. Of most value to the state's fledgling solar industry: H.B. 2405 would increase from 0.5 percent to 3 percent the amount of solar power utilities would have to provide by 2024.

The current minimum of 0.5 percent by 2021 has been in place since 2004, when Pennsylvania first instituted alternative energy use standards.

With Delaware moving to 3.5 percent, Maryland to 2 percent, and New Jersey setting new megawatt requirements that equate to about 3 percent, Pennsylvania is losing solar ground in the region. That puts it at risk of losing the approximately 600 solar businesses it has and being unable to lure others, industry advocates contend.

So instead of waiting until next year to renew the push for passage of H.B. 2405, solar proponents are launching a new plan of attack.

They want the legislature to embrace the idea of a stand-alone bill that would hike the state's solar-energy requirements only. That would leave other aspects of the controversial H.B. 2405 - nuclear power and clean coal, for instance - for later consideration.

"It's really important we have this bill to move the industry from a rebate-dependent energy source to a more market-driven energy source," Maureen Mulligan of Sustainable Futures Communications said in an interview. She is the chief lobbyist in Pennsylvania for the two largest solar-energy trade associations in the region: Solar Alliance and the Mid-Atlantic Solar Energy Industries Association/Pennsylvania division.

Mulligan will attempt to make her case for a solar-only bill at a House Majority Policy Committee hearing on alternative-energy issues in Worcester, Montgomery County, Wednesday afternoon.

In an interview Tuesday, John Hanger, Pennsylvania's environmental secretary, said a solar-only bill "would be certainly better than doing nothing in the fall."

"What's troubling is we're falling behind neighboring states," Hanger said. "The competitive impact is even greater than if we were falling behind Arizona."

H.B. 2405 had been opposed by Pennsylvania's dominant coal industry over fears that enhanced requirements for alternative-energy sources would cut into its market share and put miners out of work.

The measure was also opposed by the Pennsylvania Chamber of Business and Industry because, among other reasons, it prioritized some forms of alternative energy over others. A solar-only legislative proposal "doesn't change our thinking on the issue," especially given that solar "is the most expensive component" of the state's alternative-energy mandate, said Eugene Barr, vice president of government and public affairs for the chamber, whose members include both coal and solar businesses, he noted.

H.B. 2405's prime sponsor, State Rep. Eugene DePasquale (D., York), said Tuesday he is willing to sponsor a solar-only initiative, but "I don't want to raise anyone's false hopes - I saw what happened with 2405."

He won't have much time. Just 17 legislative days are left in the year when the House returns to work on Sept. 13; the Senate on Sept. 20, Mulligan said. Plenty of weighty issues already await attention, including a proposed severance tax on natural-gas extractions from the Marcellus Shale, and transportation concerns.

Among those hoping legislators will make room to consider a solar bill is Jim Pierobon, vice president of policy and market development for Standard Solar. The Maryland-based company would have offices established in the Philadelphia and Pittsburgh areas within three to six months of passage, Pierobon said.