05 Feb Grandview, Idaho
PV Project Optimization Analysis and Review
WorldWater and Solar Technologies, Inc. was contracted by Hanwha Q Cells USA Corp., to provide specific engineering design review and analysis across an 80MWAC project in Grandview, Idaho. We were tasked primarily to provide “value engineering” and “optimization” solutions that will discover areas of design, layout, configuration and equipment deployment that maintain or enhance Hanwha’s expectations.
PV system performance has been modeled for five different solar panels and three inverter configurations, including the currently used 1,050kW inverters and the larger 1,250kW inverters. The financial performance of the project was evaluated using an financial model with 30-year internal rate of return (IRR) and net present value (NPV) as the main outputs. An 8% cost of capital was used for the NPV (20% equity @ 16% and 80% debt @ 6%). Though the exact numbers might not match those used by Hanwha’s finance team, the trends should be similar.
Two variables that were given specific attention are the ground-coverage ratio (GCR)1 and the DC/AC ratio. The DC/AC ratio currently used for Grandview West optimizes the NPV, but is slightly high for optimal IRR. A decision will have to be made on whether to seek to optimize IRR or NPV. (The latter is better when there is no resource constraint.) See the IRR vs NPV Optimization section of the Executive Summary below for more details. For Grandview East IRR is optimized, optimizing NPV requires adding more DC power.
The larger inverters improve the financial performance of the project. For Grandview West, using 1,250kW inverters throughout improves the projected 30-year IRR by 0.22% and adds about $1.2 million dollars to the 30-year NPV. In reality a combination of 1,050kW and 1,250kW inverters is most practical due to the land size and shape constraints.