Archive for February 20th, 2011

DC Power Devices in PV Installations

February 20, 2011

The design of PV systems tied to the AC grid requires a DC-AC inverter to convert DC from the solar panel to AC power, for use by AC-powered devices or to feed-in to the utility’s AC grid, the latter operation also requiring power conditioners. The DC-AC conversion process is less than 100% efficient. The losses are similar to ones imposed by step-down transformers and vary by equipment nameplate efficiency.

To maximize the power harvested, one may use DC devices as possible, avoiding the loss inherent in the inverter. Solid state lighting (SSL) including LED offers such an opportunity, increasing the systemic energy efficiency by both providing greater Lm/W over incandescent and fluorescent sources and by capturing the energy lost through the inverter to the AC portion of the distribution system.

The number of available DC devices in buildings is limited, typically elevators and SSL, and equipment such as lifts and cranes in industrial applications, including boat lifts. Distribution with the above strategy is also made somewhat more complex. Consequently a cost-benefit analysis should be undertaken for any particular building project or retrofit.