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There are few more obvious places for solar-energy systems than the headquarters of the US Department of Energy and the US Airways Center arena (well, the parking structure anyway) of the National Basketball Association's Phoenix Suns. DOE's new panel array was officially inaugurated earlier today (Tuesday) in Washington, DC, while the Suns' PV plans were announced the end of last week.

If I have to explain why these two very public examples of solar's growing power are so blatantly symbolic and inherently promotional, then please stop reading now. But if you get it, here are some details.

The DOE array has been generating electricity since August 1, while the switch will be flipped on the Suns' rooftop/carport solar system in spring 2009--during the NBA season, of course.

Both systems aren't huge megawatt-scale projects, but are still respectable in size, with DOE's at 205 KW and the Suns' at 194 KW.

DOE says the system will provide up to 8% of the Forrestal Building's energy needs, although no mention has been made of when similarly sized solar-panel arrays can be expected to be installed on or near the White House, US Capitol, or other federal government locales in the District. Hello Obama and McCain camps, do you read me, over?!

The Suns characterize the energy gain in terms of reduced load on the Casino Arizona Pavilion (AKA the parking structure) part of the US Airways arena complex at 25%. The electricity generated will be enough to offset the power used in 26 Suns' home games (win or lose), though no calculation has been made of the energy-offset equivalent that star point-guard Steve Nash expends every time he takes the court.

Each system relies on crystalline-silicon-based modules. DOE's employs 891 SunPower 230s, each with 72 monocrystalline cells and each box capable of 18.5% conversion efficiency. The Suns will rely on 1125 Suntech STP 200s, which sport 54 multicrystalline cells and can reach efficiencies of 13.6% at the module level.

While both modules are only a few inches thick, the SunPower units weigh 15 kg, and the Suntechs come in at 16.8 kg. This means that the weight load for the panels alone will be 13.4 metric tons at DOE and 18.9 metric tons at the Suns' house, er, garage, plus the additional tonnage of the racks, inverters, etc.

A bonus of the DOE installation is that insulation incorporated in the modules may lead to an additional energy savings of as much as 30%, because of the decreased heating and cooling load--all part of SunPower's nonpenetrating PowerGuard integrated PV roofing system.

While I haven't seen anything to suggest that DOE's system is part of a power purchase agreement (although that would be quite ironic, if it were the case), Tioga Energy will finance, own, and operate the Suns array and sell the power to the arena under a PPA, after EI Solutions gets done designing and installing it. Standard Solar and altPower did the heavy lifting and put DOE's PV plant in place, with the US General Services Administration also involved heavily.

Both announcements contain the obligatory and increasingly cliché carbon-footprint reduction statements. In DOE's case, the agency says the new PV will help it "avoid annually the emission of up to 186 metric tons per year of greenhouse gases." Of course, the retirement or electoral defeat of many members of Congress--and the departure of the current presidential adminstration--will also result in a substantial reduction of other gases known to be harmful to the environment.

As for the Suns, the "system is expected to reduce carbon dioxide emissions by 440,000 pounds each year, the equivalent of planting 46 acres of pine trees"--a curious choice of arboreal species, given that the words "pine tree" and "Phoenix" are rarely uttered in the same breath. I guess "saguaro" just doesn't have the same ring to it.

Although both the DOE and Phoenix Suns' new solar-power plays don't come close to the massive millions-of-watts scale seen in many of the utility and commercial PV and CST farms built or announced over the course of the past year, they do provide excellent PR for the inexorable expansion of the photovoltaic revolution.