This document describes a high level technical design for and the economic assessment of renewable
energy solutions for radio base stations (RBS). It proposes a way forward in the development of
'hybrid' solutions with renewable energy sources (RES) for off-grid RBS sites.
The main purpose of this document is to provide initial practical, technical and economic guidance.
The following sections outline the specific requirements of mobile operators and provide specific
technical guidance for the selection and implementation of the elements of a hybrid system.
This information will enable mobile operators without any detailed technical and commercial
knowledge to develop initial ideas on the design of such a system and provide them with a common
basis for further discussion, evaluation and benchmarking.
References to external documents in the glossary are in square brackets [ ] and cross links to specific
sections of this document are indicated as follows: >> section_name.
Note: this document is part of my final examination in the renewable energy study module at the
University of Kassel. The precise definition of the term paper can be found in >> Issue definition
Table of Contents
1 Introduction
1.1 About this document
1.2 About the author
1.3 Issue definition
1.4 Scope
1.4.1 In scope
1.4.2 Out of scope
2 Mobile operators
2.1 Role and motivation
2.2 Technical context
2.3 Technical characteristics
3 How to get RES@RBS
3.1 Network perspective: prerequisites (macro view)
3.2 Site perspective: planning steps (micro view)
4 Selected technical recommendations
4.1 General
4.2 Technical design
4.3 Solar
4.4 Wind
4.5 Batteries
4.6 Charger, controller
4.7 Diesel generator
4.7.1 Accessories (cabling)
5 High level RES assessment (RAFORS)
5.1 Purpose
5.2 Abstract
5.3 Simplifications / restrictions
5.4 How to work with RAFORS
5.4.1 General
5.4.2 Input data
5.4.3 Output
5.5 Calculation
5.5.1 Power
5.5.2 PV
5.5.3 Battery
5.5.4 Wind
5.5.5 Diesel generator
5.5.6 Economic aspects
5.6 Way forward
7 Appendix
7.1 Example of a ‘Site questionnaire to plan RES based radio stations’
7.2 Example of a 3-phase design
7.3 Example of an RES@RBS assessment with RAFORS
7.4 Suppliers (examples)
7.5 Symbols (electrical)
Objectives & Core Topics
The primary objective of this document is to provide mobile operators with practical technical and economic guidance for the design and assessment of renewable energy solutions (RES) for off-grid radio base stations, specifically utilizing the provided RAFORS Excel tool to evaluate net present costs (NPC).
- Technical design of hybrid energy systems for radio base stations.
- Economic assessment and benchmarking of various renewable energy alternatives.
- Integration of solar, wind, and diesel generator components.
- Standardization of site planning through a systematic questionnaire and logical assessment process.
- Reduction of operational expenditure (OPEX) and CO2 emissions through sustainable energy strategies.
Excerpt from the Book
4.2 Technical design
Although the load requirements are mainly DC, the air-conditioning system may require some AC. Diesel generators are also used as a back up or main power source at most sites. As a result, a ‘mixed’ design has to be applied. The diagram below shows the two possible designs.
The power generators are on the left hand side of the diagrams and the BTS load is on the right hand side in the shadowed boxes. A key to the symbols is provided in the annex > Symbols.
The bi-directional battery charger is a bottleneck in the ‘mixed’ design on the right hand side. However, this might be an acceptable drawback since relatively stable or even decreasing load demand is expected in future >> Technical characteristics.
Both designs can be adapted. For example, it would be possible to start off with the mixed design, which allows diesel generator (DG) backup, and phase out the DG at a later time. This evolutionary process is shown in the following diagram:
Summary of Chapters
1 Introduction: Outlines the purpose of the document as a practical guide for implementing hybrid renewable energy solutions in telecommunications, supported by the RAFORS assessment tool.
2 Mobile operators: Analyzes the environmental responsibility of the ICT sector and explains the technical characteristics of power consumption in radio base stations.
3 How to get RES@RBS: Describes a step-by-step approach for energy optimization, moving from network-level design to site-specific planning for renewable energy integration.
4 Selected technical recommendations: Provides specific guidelines for technical components, including solar PV, wind generators, battery systems, controllers, and diesel backups.
5 High level RES assessment (RAFORS): Explains the functionality, mathematical models, and input logic of the RAFORS assessment tool for calculating the net present costs of hybrid systems.
7 Appendix: Contains practical templates, such as a site planning questionnaire and detailed examples of 3-phase system layouts and real-world assessments.
Keywords
Renewable Energy Sources, Radio Base Stations, Hybrid Systems, RAFORS, Net Present Costs, OPEX, CAPEX, Mobile Operators, Solar PV, Wind Turbine, Diesel Generator, Energy Efficiency, Telecommunications, Sustainability, Technical Design
Frequently Asked Questions
What is the primary purpose of this paper?
The paper provides a technical and economic framework for mobile operators to design and assess renewable energy solutions for off-grid radio base stations, supported by a specialized Excel tool called RAFORS.
What are the central topics addressed?
The work covers system design, resource assessment (solar and wind), component selection (batteries, chargers, generators), and the economic calculation of project viability.
What is the core research question or goal?
The goal is to provide a standardized, easy-to-use method for operators to evaluate the net present costs (NPC) of transitioning from traditional power sources to renewable energy hybrids.
Which scientific methods are applied?
The study uses an analytical approach to dimensioning hybrid energy systems and applies net present cost (NPC) modeling to determine the economic benefits of renewable energy integration.
What is covered in the main section?
The main part details the technical configuration of "mixed" and "DC only" sites and provides specific calculation formulas for PV energy yield, battery capacity, wind power output, and system maintenance costs.
Which keywords characterize the work?
Key terms include Renewable Energy Sources (RES), Radio Base Stations (RBS), Net Present Costs (NPC), hybrid systems, and telecommunications energy management.
What role does the RAFORS tool play?
RAFORS serves as an Excel-based decision support tool that allows users to input load and site data to calculate the technical requirements and economic outcomes of various hybrid energy scenarios.
How is a "mixed design" defined in this context?
A mixed design refers to a site architecture that utilizes a combination of DC power (for radio equipment) and AC power (typically for air conditioning or as a backup via a diesel generator).
Why is the diesel generator considered a fallback option?
Due to high OPEX and environmental impact (CO2 emissions), the author suggests the diesel generator should only be used as a temporary backup to ensure site autonomy, with the goal of eventually phasing it out.
- Citation du texte
- Dipl.-Wirt. Ing, Dipl.Kfm. Heinz Rüterbusch (Auteur), 2008, High level technical design and economic assessment of renewable energy solutions for radio base stations, Munich, GRIN Verlag, https://www.grin.com/document/115425
