Stalking Solar Retail Grid Parity: the PV Cost Calculator

Courtesy of the U.S. Department of Energy’s Solar America Cities program, the PV Cost Calculator is a system modeling tool, which computes and then provides various visualizations of solar PV’s trend toward retail grid parity in the next few years. The calculator is designed for residential (4kW size) and small commercial (20kW) installations. Retail grid parity is when the levelized cost of energy is same as retail priced energy from the utilities in a given region.

Modeling grid parity, whether in front of (retail) or behind (wholesale) the utility meter, is a notoriously difficult endeavor due to the large number of variables. The PV Cost Convergence Calculator models a complex set of variables that are highly dependent on local issues.  It takes into account long term federal and state incentives and provides a 20 year analysis period.

The screen shot below is for a 20kW commercial system using a moderate scenario – 4% increase in conventional utility energy cost and moderate decrease of the PV system price. With this scenario, the majority of Solar America Cities are at or below retail grid parity in 2012.

Solar Grid Parity

Dotted line - utility cost with 4% annual inflation


The PV Cost Calculator makes a number of assumptions to simplify the calculation set and is meant as an illustration for Solar America program cities.  Another DOE agency, The National Renewable Energy Laboratory provides a sophisticated, detailed PV system modeling tool called the Solar Advisor Model (SAM). SAM makes performance predictions and economic estimates for grid-connected solar systems. The SAM model calculates the cost of generating electricity based on information you provide about a project’s location, installation and operating costs, type of financing, applicable tax credits and incentives, and system specifications. The SAM model is an invaluable tool for feasibility modeling of a proposed project and for working with project financing entities. Its also an interesting tool which we use for targeting the sales process of PV system components.

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