Apple's Maiden NC solar project

As Apple continues to develop a data center to handle its iCloud service, some details are emerging about the energy infrastructure to be built at the Maiden, North Carolina facility.  Two public filings Apple made last month to the Federal Energy Regulatory Commission describe the Maiden data center's solar photovoltaic and fuel cell systems.

Under federal law, certain efficient or renewable electricity generation facilities can certify themselves as "qualifying facilities" or QFs.  The Public Utility Regulatory Policies Act (PURPA) of 1978 required monopolistic electric utilities to buy power from QFs, as long as that cost was less than the utility's own "avoided cost".  Generally, a utility's avoided cost is the cost of the power the utility would have procured from a source other than the QF in question.  This policy was intended to improve the efficiency of the nation's fleet of electric generation, as lower-cost QFs displaced more expensive traditional utility generation.

In April, Apple submitted two filings to FERC certifying its planned Maiden solar and fuel cell systems as QFs.  These documents provide additional insight into Apple's plans.

In its solar photovoltaic project self-certification, docketed by FERC as QF12-328, Apple described the project:

Each of the photovoltaic installations will consist of multiple 435-watt photovoltaic modules on ground-mounted single-axis tracking systems. The current design includes 57,360 435-watt modules. The modules will be connected in series strings of 10 to achieve the appropriate DC voltage. The modules will track the sun by rotating about a north-south axis. At the current time, we expect 14 photovoltaic installations will make up the solar farm: ten 1.50 MW installations and four 1.25 MW installations. The final number of installations and modules will depend on detailed design considerations in consultation with the utility, the photovoltaic system provider, and local permitting authorities. Each installation will be connected to two 750 kW or two 625 kW inverters. Inverters will convert the DC current produced by the systems to AC current. A step up transformer is installed between the inverter outputs and the point of connection to Duke's distribution system. Each installation has a dedicated transformer. The photovoltaic installations will be installed in a phased manner, whereby the installations will be interconnected as they are completed.

Check out tomorrow's blog entry for a look at Apple's biogas fuel cell facility.