Five years ago, Fresno, Calif., Local 100 was in deep trouble.

"We were looking at Depression-era unemployment, 35-40 percent of our 800 members were on the bench and most of the ones working weren't seeing a full 40 hours in a week. We lost more than 100 members," said Local 100 Business Manager Kevin Cole. "The economy around here was devastated. Solar saved this local."

In the last two years, Cole said, total hours worked are nearly back to pre-recession levels and solar projects have accounted for nearly 80 percent.

Across Southern California, grid-scale solar projects — those larger than 50 megawatts, often much larger — have been going up at an unprecedented rate, buoying the fortunes of nearly a dozen construction locals. The state now has enough solar capacity installed to power more than 2.25 million homes, nearly all of it built in the 10 counties south of San Luis Obispo in the last three years.

The abundant sunshine and thousands of square miles of desert range have held out promise since photovoltaics were first commercialized 40 years ago, but three forces have come together to bring that promise to fruition. First, the price of solar panels has been falling rapidly: more than 75 percent since 2006. Second, the 30 percent federal investment tax credit that debuted in 2006 and was extended in 2008, provided an automatic, reliable incentive that made multibillion dollar solar projects more attractive to lenders and investors.

Finally, in 2011, Gov. Jerry Brown assigned an expansion of California's renewable portfolio standard, increasing the amount of energy the state's utilities had to source from solar, wind, geothermal or hydroelectric from 20 to 33 percent by the year 2020. The state's utilities went on a buying spree, locking in decades-long power purchasing agreements with solar developers at fixed prices, removing a great deal of risk for developers and investors.

"The IBEW up and down the state had a large presence in Sacramento advocating for the RPS expansion," said San Diego Local 569 Business Manager Johnny Simpson. "I won't say it wouldn't have passed without us, but we worked very hard to get it done and I think it has paid off for the state and for our members."

Membership in Local 569 jumped from 2,100 in 2011 to 3,300 in 2013. The eastern half of 569's jurisdiction is the sparsely populated Imperial County. In 2012, there were only 60 members in a county about the same size as Connecticut. One year later there were more than 800.

"Solar has been a wonderful industry for us," Simpson said.

Some of the largest solar projects in the world have been built by IBEW members, including the 392 mw Ivanpah plants — built by members of San Bernardino Local 477 — which produce enough power for nearly 400,000 homes, and the 500 mw Topaz projects, still under construction by members of San Luis Obispo Local 639.

Riverside Local 440 has seen similar success. Business Manager Bob Frost said membership has grown nearly 50 percent since 2011 to almost 1,000 members, and nearly 60 percent of their work in recent years has been solar.

Perhaps no local has been as dramatically affected by the solar boom as Bakersfield Local 428. In six years the local has grown 40 percent, and gone from 25 percent of the members laid off to supporting dozens of travelers. Since 2013, more than half of the membership has been working on a single job, the 580 mw Solar Star projects.

"We have proven to the owners that there is a huge advantage in hiring the IBEW," said Business Manager Jim Elrod. "At first many of them were afraid of organized labor, but they had very little success hiring people off the street. Our national pool of highly qualified workers was very valuable. Then we showed how the strength of our roots in this community would help get their projects approved."

There are signs that the pace of solar construction might slow down. The federal tax credit is scheduled to expire at the end of 2016, and as utilities get closer to the 33 percent goal offering less desirable terms in power purchasing agreements, most Southern California locals said they expect at least a few more years of significant work in the California solar fields.

"Because we've had so much work in the solar fields we can take our time and more successfully target nonunion contractors doing other kinds of work. Romance them a bit," Elrod said. "If solar is a fad, we'll be more diverse and bigger than before."

Nevertheless, the Solar Energy Industry Association reported that California will build as much solar capacity in the next year as was built in the last 30 years combined and nearly 19,000 mw is under development in the state. San Bernardino Local 477, for example, has a PLA in hand to build a 1,200 mw project — four times larger than the largest solar plant in the world, Ivanpah, which was also built by Local 477.

"All this green energy has been very, very good to the IBEW," said San Diego Local 569 Business Manager Simpson.