Take this statistic with a grain of salt.

Silicon Valley has seen its so-called “smart grid” sector boom over the past decade, with a 138-percent growth in business activity, compared to average regional economic growth of 82 percent, and a 129-percent growth in employment, compared to the region’s anemic 8-percent job growth across all sectors.

All in all, 12,560 people were working in “smart grid-related” jobs as of 2009, according to a joint study from the Silicon Valley Leadership Forum, regional utility Pacific Gas & Electric and the city of San Jose.

It’s a great advertisement for green jobs -- but the report’s use of the term “smart grid” is a bit misleading.

That’s because nearly three-fifths of all the jobs cited in the study, some 7,450 in all, are in the “distributed generation” category, which includes San Jose-based SunPower and scores of other solar power companies in the region, as well as those that test and support distributed power systems. SunPower does do a lot of monitoring of its panels and is adding microinverters to its mix. Both are potential linkage points to the smart grid that could be important when utilities decide they need to monitor and manage all their new, intermittent solar power. Still, the connection to smart grid is pretty tangential.

Fuel cell companies like Bloom Energy, Deeya Energy and Oorja are also included, but in a weird way -- they’re classified under “energystorage” a category you’d think wouldn’t apply to technology that needs natural gas, methanol or hydrogen fuel to generate power. Batteries and uninterruptible power systems are also included to give the sector 1,850 jobs, or 17 percent of the total. While plenty of grid storage projects are in the mix, I’d bet most of these jobs are in backing up the region’s power-hungry data centers -- though those too are being connected to the smart grid in pilot projects.

What’s left? Transmission and distribution grid technologies, which captures the region’s big smart grid networking players like Silver Spring Networks, Trilliant and Echelon, accounted for 1,230 jobs, or 10 percent of the total. The rest is made up of power management and energy efficiency companies, which includes smart grid software players like eMeter, EcoFactor and Sentilla, as well as chipmakers like Teridian and Exar, and accounts for 1,800 jobs in the four-county region (Santa Clara, San Francisco, Alameda and Contra Costa).

Taken together, those two classically “smart grid” sectors add up to 3,030 jobs -- not nearly as impressive as the headline number. Still, let’s give the study credit for highlighting that solar power, fuel cells, batteries and buildings aren’t separate from the smart grid, but rather are a part of it. Now comes the tricky stage of getting them all to work together.

And one more question: was Cisco included?