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Off-grid solar energy storage system with lithium iron phosphate (LFP) batteries in high mountains: a case report of Tianchi Lodge in Taiwan

Hsien-Ching Chung

TL;DR

The paper presents a detailed case study of Tianchi Lodge, a high-altitude mountain hut in Taiwan, powered by an off-grid solar energy storage system using lithium iron phosphate (LFP) batteries since 2020. It documents the system architecture, including $11.2 kW_p$ of PV, a $75 kWh$ LFP ESS with a $48 V$ DC nominal, a $15 kW$ hybrid inverter setup, and a $20 kW$ diesel backup, as well as the lack of a centralized EMS. The historical narrative shows a transition from lead-acid ESS to eco-friendly LFP batteries to improve environmental performance and reliability in harsh alpine conditions. The paper also identifies the absence of EMS as a gap and outlines practical steps to monitor energy flows, optimize operation, and potentially expand capacity to minimize diesel usage in high-altitude settings.

Abstract

Mountain huts are buildings located at high altitude, providing shelter and a place for hikers. Energy supply on mountain huts remains an open issue. Using renewable energies could be an appropriate solution. Tianchi Lodge, a famous mountain hut in Taiwan, has operated an off-grid solar energy storage system with lithium iron phosphate (LFP) batteries since 2020. In this case report, the energy architecture, detailed descriptions, and historical status of the system are provided.

Off-grid solar energy storage system with lithium iron phosphate (LFP) batteries in high mountains: a case report of Tianchi Lodge in Taiwan

TL;DR

The paper presents a detailed case study of Tianchi Lodge, a high-altitude mountain hut in Taiwan, powered by an off-grid solar energy storage system using lithium iron phosphate (LFP) batteries since 2020. It documents the system architecture, including of PV, a LFP ESS with a DC nominal, a hybrid inverter setup, and a diesel backup, as well as the lack of a centralized EMS. The historical narrative shows a transition from lead-acid ESS to eco-friendly LFP batteries to improve environmental performance and reliability in harsh alpine conditions. The paper also identifies the absence of EMS as a gap and outlines practical steps to monitor energy flows, optimize operation, and potentially expand capacity to minimize diesel usage in high-altitude settings.

Abstract

Mountain huts are buildings located at high altitude, providing shelter and a place for hikers. Energy supply on mountain huts remains an open issue. Using renewable energies could be an appropriate solution. Tianchi Lodge, a famous mountain hut in Taiwan, has operated an off-grid solar energy storage system with lithium iron phosphate (LFP) batteries since 2020. In this case report, the energy architecture, detailed descriptions, and historical status of the system are provided.

Paper Structure

This paper contains 15 sections, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. About Tianchi Lodge
  3. Current status
  4. Brief history
  5. Alpine transportation supplement
  6. Architecture of energy system
  7. Photovoltaic systems (PV systems)
  8. Hybrid solar inverters
  9. LFP energy storage system (ESS)
  10. Battery management system (BMS)
  11. Loads
  12. Backup power system
  13. Energy management system (EMS)
  14. Historical development of energy systems
  15. Summary and Outlook

Figures (3)

  • Figure 1: Aerial Photography of Tianchi Lodge (2019). (Photographer: Yu-Chun Lin)
  • Figure 2: Energy architecture of Tianchi Lodge (2020). Energy input is provided in part by PV arrays and a diesel generator. The hybrid solar inverters directly supply power to the lodge's 220 V$_\mathrm{AC}$ load. The power of the 110 V$_\mathrm{AC}$ load is obtained through a transformer (220 V$_\mathrm{AC}$ / 110 V$_\mathrm{AC}$). An ESS stores and releases intermittent renewable energy from PV arrays. A diesel generator is used as the backup power source.
  • Figure 3: Machine room of Tianchi Lodge (2022).