On April 2, almost a million ratepayers served by San Diego Gas & Electric, or SDG&E, had their power cut to avoid an uncontrolled blackout that could have created a cascade failure far outside of SDG&E’s service territory.

The intentional cutback, to about 20 percent of electricity subscribers, or about 300,000 homes, was initiated by the California Independent System Operator, or Cal ISO, and reportedly resulted from too many power plants being shut down for routine maintenance, which initiated a cascade failure.

Or not; Cal ISO and other state and regional electricity officials haven’t offered an explanation for the blackout, which UCAN’s Executive Director Michael Shames describes as a “remarkable mystery”. UCAN, or Utility Consumers’ Action Network, is a San Diego watchdog group that assists consumers on energy, utility and Internet concerns.

SDG&E’s spokeswoman Stephanie Donovan admitted her company didn’t know the reason for the Cal ISO request, only that the utility had been asked to drop to 310 megawatts of production.

Gregg Fishman of Cal ISO hedged by suggesting that his entity had to do more fact-finding before any conclusions could be drawn. Fortunately, power was back on by late morning in most areas.

In the aftermath, many are blaming Calpine Corporation’s Otay Mesa unannounced power plant shutdown. The fact is, Cal ISO was caught in a web of arcane regulations that required damping power to prevent local grid instability, and – according to Shames – a possibility that “someone entered the wrong number into the computer”.

In any case, as one regional blogger has repeatedly noted, dependence on any part of the nation’s archaic and aging power grid is a recipe for failure, and the installation of a “privatized” power supply, like solar photovoltaic panels, isn’t just good environmental sense, it’s good sense in general. It is also a lesson that might have been driven home to many area residents when the power again went out after the April 4, 7.2 Baja earthquake.

For those SDG&E-area customers who have had their fill of outages (and summer isn’t even here yet!), consider the possibility of a 1-kilowatt, off-grid solar power system for about $5,000, after applicable tax credits and rebates – though off-grid systems don’t qualify for as many as on-grid systems.

This 1 kilowatt isn’t enough electricity to power an entire home (for that, you would need about 5 kilowatts), but it will easily keep the lights burning, and one information source (i.e., a computer, laptop or radio) running.

UPDATE: Response from Norma Dunn, Calpine Representative:
"This was not an unannounced power plant shutdown. SDG&E has full dispatch rights to the Otay Mesa Energy Center. We use "day ahead" scheduling and we were given instructions to shut down at midnight by SDG&E. We called them at 11:30pm to confirm and they confirmed that we were to shut down at midnight. At 12:01 am, SDG&E called us and asked us to turn the plant back on. One of our units came back on at approx. 3 am and the second one came back on at approx. 4 am. This ramp up time is the fasted we can come back on-line after shutting down.

This was certainly not an unannounced power plant shutdown. We were asked to shut the plant down and we did as requested. It is our obligation to follow dispatch instructions we receive from SDG&E."