Comparison of Utility-scale Solar Power Generation Technologies in Yunnan Province, China

Abstract: The present work delivers a comparison between two solar power technologies, namely photovoltaic (PV) and concentrated solar power (CSP), for various practical cases in the Chinese province of Yunnan. The comparison includes the cost of power generation variability in the project economics to make a fair comparison between the alternatives. In their use, CSP is hybridized with fossil fuels (CSP) whereas PV is combined with a battery pack (PV+B), with an internal combustion engine generator set (PV+E) or with a transmission line to a robust grid connection where transport capacity may be assumed unlimited (PV+T). Initially, eight potential cases were defined based on their proximity to a robust grid infrastructure, availability of natural gas, and residential or industrial electrical demand profiles. Locations were found in Yunnan province for seven out of the eight potential cases. Typical meteorological year weather files were obtained for these locations. Industrial and residential demand profiles were built for the comparison. The peak power demand to be satisfied was assumed 10 MW and the net load equal to the typical profiles. Thereafter, the main components of each type of power plant were selected. Based on literature search and calculations, techno-economic parameters and scaling variables were calculated. These included, among others, losses and efficiencies, capital costs per square meter and emissions per installed megawatt. Finally, various CSP and PV solar field sizes were simulated in System Advisor Model (SAM) at each location and an Excel-based model was built to deliver the economic, emissions and energy performances of each technological alternative based on the interpolation of SAM’s output. SAM model was fed with the weather files and the solar field parameters, while the Excel-based developed model incorporated some of the weather information, SAM’s output, demand profiles and techno-economic parameters which did not belong to the solar field. Readers must be aware that the results are only applicable to the selected sites, in the Yunnan province and grid context and that assumptions on imports and unsupplied demand might overestimate the performance of PV technologies. The main conclusions are that: (i) if large transport capacity is available in the vicinity, PV and fossil fuel alternatives economic performances are similar, even if low-cost natural gas is available; (ii) PV in combination with an internal combustion engine makes economic sense above a fuel cost of 8.09 - 14.35 $/GJ; (iii) a solar thermal field is required to replace diesel to be a wise financial election in most locations; (iv) a minimum valuation of ~300 $/MWh is needed to justify battery storage and, in this case, the over dimensioning of the PV field can replace batteries to deliver the same economics; (v) PV+T with a 9 to 11 MWdc field is the best alternative in almost all cases with fuel cost above 3.67 $/GJ, if the distance less than ~80 (8.09 $/GJ), ~210 (14.35 $/GJ) and ~360 kilometers (22.86 $/GJ), depending on the fuel price; (vi) PV+E consistently outperforms CSP, and its ideal PV field size is between 16-25 MWac, depending on the fuel cost; (vii) PV+T and PV+B show low emissions and high Energy Return On Energy Invested (EROEI) while CSP and PV+E show high emissions and rarely recover the energy invested in them; (viii) despite PV+B is never among the soundest economic alternatives, it always performs better than CSP in emissions and EROEI, and it is more economic in solar shares above ~70%; (ix) PV+B can supply up to 90% of the demand at a reasonable cost.