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Several times since early May, when Chip Shots carried the inside scoop that First Solar had been awarded the bid for the first installation in Southern California Edison's 250-MW, $875-million five-year project to install photovoltaics modules on a couple of square miles of commercial rooftops in the region, I had tried without success to get the Edison people to confirm my information.

Last week, when I was swept up in the hurly-burly of Semicon/Intersolar in San Fran, the official news came out from both Edison and First Solar that the cadmium-telluride thin-film PV kingpins had won the job. The announcement also mentioned Edison's and First's agreement, under a PPA, to build a 7.5--21-MW ground-mounted solar PV power plant in the southeastern California desert near Blythe (actually not far from the PV-powered state prisons covered in another blog). Then a little earlier today (or later tomorrow, if you're on the other side of the dateline), First came out with a self-congratulatory press release ballyhooing the inauguration of its first module-manufacturing line in Kedah, Malaysia.

I've had a chance to compare my original early April commentary on Edison's rooftop PV project with the recent announcements, and would like to point out a few changes in the info and the numbers.

"Dang, I thought we were only getting 20,000 panels!"
(Photo courtesy: Southern California Edison)

The early reporting had the first module installation starting on top of the ProLogis-owned Kaiser Distribution Center in Fontana in June, when actually it began July 14 or July 16, depending on whether you believe the First or Edison PRs, respectively. Another scrap from the initial stories said the system would come online in August or September, the period of high peak power use in a hot zone like SoCal's Inland Empire. The latest info skips any mention of August and states that the system will grid-connect in early September. Finally, the early estimates put the total number of commercial roofs expected to be photovoltaicized at around 100, now the number has ballooned a bit to about 150.

Edison's original module estimate for the job was around 10,000 panels per megawatt, for a total about 2.5 million for all 250 MW, once installed. That comes out to a nice, round 100 W per module. Also, the first installation was given as 2.2 MW, which would have calculated to 22,000 panels, give or take.

The latest numbers put the number of panels much higher and the size of the initial rooftop array a bit smaller. Some 33,000 FS Series 2 CdTe modules will be racked up on top of the warehouse (will it be the 60, 62, or 65 W models, given the +/- 5% nominal power rating?), capable of providing 2 MW of juice to the grid. That's alot more panels for 200 KW less power output, but then again, those are units with conversion efficiencies of ~10% but a lighter/smaller footprint and more attractive price tag than many of the competitors' silicon-based modules.

What do those 33,000 modules and 2 MW represent in terms of what First expects to install worldwide this year? About 0.5% of the 400 MW planned for plug in.

For the sake of argument, say First Solar eventually wins all the Edison bids to supply all the modules. Instead of that original Edison estimate of 2.5 million, the total number of panels needed would be in the neighborhood of 4.125 million, at today's specs and capabilities. Allowing for better efficiencies and higher power outputs, that number might dip below 4 million, but not by much.

But I doubt that the TFPV leader will win all the business, since Edison wants to use the project to compare and contrast different types of PV. In a few years, with the installations quite well along, the first concentrator PV modules and CIGS-based panels might be in the bidding mix, as long as their price points are low enough for the extra conversion efficiency pop they will provide, which would significantly lower the actual number of units needed per megawatt.

In the meantime, if a non-thin-film PV module-maker wins the next bid, Edison won't have to change the little graphic and explanation at the bottom of its most recent press release that depicts how a solar cell works--a wafer-based, crystalline silicon cell, that is, with nary a CdTe (or any other) thin-film-layer-on-glass shown or mentioned.