Presentation Details
| Validation Study of Soil Modeling Approach for Underground Ampacity Calculations in Ground Mount Photovoltaic Solar Projects Beri Gershwind, Andrew Melvin. Ulteig, Denver, CO, USA |
Abstract
Accurate modeling of soil thermal properties is essential for determining underground cable ampacity in ground mount photovoltaic solar projects. Current industry practice often simplifies soil conditions by assuming a single thermal resistivity value derived from worst-case temperature and moisture occurring simultaneously. However, real soil exhibits variability in temperature, moisture, and resistivity with depth and over time, making these assumptions potentially inaccurate. This study evaluates the impact of these simplifications by comparing two modeling approaches using CYMCAP: (1) a standard simplified model and (2) a detailed model incorporating depth-dependent soil characteristics and temporal variability. Data were collected from USDA SCAN sites and geotechnical reports across five geographically diverse project locations within the continental United States. Results indicate that the simplified model underestimates worst-case cable ampacity by approximately 2-9% compared to the detailed model, introducing a built-in safety margin. While this conservatism is significant, it is not excessive, suggesting that current practices remain generally reliable but should be considered when applying additional safety factors.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.