Reto Juvenil Internacional

NOTE: AS OF TODAY, TEXT ON THIS PAGE MAY BE FULLY OR PARTIALLY OWNED AND PROVIDED BY THE UNIVERSITY OF TORONTO, IT'S SUBSIDIARIES (The University of Toronto’s Centre for Global Engineering (CGEN) , AND/OR Reto Juvenil International (RJI)). No NDA was required for this project. Co-authors have been credited below.

General Details:

Project ID: RJI-3 - "SolOptimize"

Client: Reto Juvenil Internacional

Supervisor: Prof. Amy Bilton
Co-authors: Ibrahim Hassan, Siddarth Dhadwal, Mohit Gupta, Tony Hu

Business Identification Number (BIN): 1001369674

Summary:

Children’s Town in Bogotá provides vital support to youth escaping forced recruitment, but high electricity costs limit its ability to fund vocational training. This capstone project aims to reduce those costs by designing a solar-powered system for study rooms and dormatories, as well as  optimizing existing residential solar installations.

Problem Statement:

1.0. Background
The Children’s Town in Bogotá, supported by Reto Juvenil Internacional (RJI), serves as a safe resort for children under the age of 17 who have escaped recruitment by armed groups. The town provides them with education, shelter, and psychological care. To better support these efforts, the centre aims to optimize its expenditures and save wherever possible, with electricity being one of the key areas where reductions are feasible by implementing solar-based solutions. Reducing energy costs would allow Children’s Town to redirect savings toward broader and more focused support initiatives, including expanded mental health therapy services and scholarships for students seeking to enrol in trade colleges after the age of 17.

2.0. The Main Problem
RJI operates solely based on donations, placing multiple financial constraints. Due to this, three existing solar panels that were initially being used to supply power for water heaters could not be repaired after being damaged, rendering them useless. The facility is therefore completely dependent on the city grid supply for its electricity needs, which significantly adds to its monthly expenses. This demonstrates one of the client’s needs to re-optimize the existing damaged solar panel systems to function as planned earlier (for the hot water boiler heaters). Furthermore, because electricity costs present a significant recurring monthly expense, the facility’s finances are heavily constrained; thus, this restricts resources that could otherwise be directed toward projects that directly address children’s well-being. To mitigate this burden, the client also requires the installation of a solar-powered system to minimize dependence on the city grid for a study room that is frequently used by students, and if possible, expand the solar power supply to other areas within the facility.

3.0. Scope
The scope of this project consists of two main components. First, the team will design an optimized solar panel system capable of supplying sufficient electrical power for concurrent use of two overhead lights and fifteen laptop computers located in a 650-sq. ft. study room to substitute the existing city grid supply. Second, the team will either repair or replace, as well as re-optimize the three currently damaged solar panels, originally intended to power hot-water boiler heaters in the children’s residences, located in close proximity to the study room. The project scope also includes ensuring that the hot-water boilers continue to receive power to function from the solar panel systems. To support future reliability and utility, the project will also include the integration of batteries for energy storage, design considerations to revert to the city grid in cases of solar power system downtime or insufficient solar energy supply, and a troubleshooting guide to aid maintenance and reduce future engineering costs. Expansion of the solar power supply to other areas of the RJI facility may also be considered if time and financial resources permit.

Revised Problem Statement (summarized):

1.1. Background

The Children’s Town in Bogotá, supported by Reto Juvenil Internacional (RJI), serves as a safe resort for children under the age of 17 who have escaped recruitment by armed groups. The town provides them with education, shelter, and psychological care. To better support these efforts, the centre aims to optimize its expenditures and save wherever possible, with electricity being one of the key areas where reductions are feasible by implementing solar-based solutions. Reducing energy costs would allow Children’s Town to redirect savings toward broader and more focused support initiatives, including expanded mental health therapy services and scholarships for students seeking to enroll in trade colleges after the age of 17.

1.2. The Main Problem

RJI operates solely on donations, which creates financial constraints. Three existing solar panels, originally used to power water heaters, were damaged and left unrepaired, leaving the facility fully dependent on the city grid and facing high monthly expenses. This highlights the need to re-optimize the damaged solar panels for the hot water boilers. Additionally, because electricity is a significant recurring cost, resources are diverted from projects that directly support children’s well-being. To reduce this burden, the client also requires a solar-powered system for the frequently used study room, with the possibility of expanding the solar supply to other areas of the facility.

1.3. Scope

The scope of this project consists of two main components. First, the team will design an optimized solar panel system capable of supplying sufficient electrical power for the concurrent use of six overhead lights and fifteen desktop computers located in a 350 sqft (approximate) study room to substitute the existing city grid supply. Second, the team will prepare a maintenance and troubleshooting guide for the existing solar water heaters that are used to heat water supplied from a 500 L tank. Beyond the minimum scope, if constraints permit, the team will design the main study room solar panel system to provide electricity for two additional classrooms with the same electrical requirements as the study room (minus the computers) and/or three children’s dormitories (each of which is approximately 400 sqft and has a total of 8 lights, including the restrooms). To support future reliability and utility, the project will also include the integration of batteries for energy storage, design considerations to revert to the city grid in cases of solar power system downtime or insufficient solar energy supply, and a troubleshooting guide to aid maintenance and reduce future engineering costs for the main designed solar panel system. 

2.0. Project Analysis

The techno-economic feasibility study of photovoltaic (PV) systems in indigenous communities of La Guajira, Colombia, [8] provides a highly relevant reference for SolOptimize. The project mirrors many of our challenges: limited access to reliable electricity, the need for efficient solar deployment in a community setting, and long-term financial sustainability.

The study classified communities into three segments—S1 (small, ~8 households), S2 (medium, ~17 households), and S3 (large, ~23 households)—and conducted detailed load surveys to model daily demand profiles. Each household consumed on average 5.6–5.8 kWh/day. Systems were sized using HOMER software, yielding 9 kW (S1), 20 kW (S2), and 27 kW (S3) designs, with two to three days of battery autonomy for reliability. This approach ensured continuity of supply and fair energy distribution across households.

Economically, the systems produced electricity at 1,000–1,150 COP/kWh, higher than the national grid average (~390 COP/kWh). However, with subsidies of up to 60%, costs dropped to 400–460 COP/kWh, making PV competitive. The Guajira results highlight how subsidies and national energy policies can bring PV electricity costs close to grid levels, highlighting that policy frameworks and external donor involvement will be critical for ensuring the affordability and long-term viability of SolOptimize in Bogotá.

For SolOptimize, the Guajira case provides several direct lessons that can be adapted to the Children’s Town context. These insights span technical, economic, and organizational aspects, ensuring the project is both reliable and scalable.

Load profiling and demand segmentation: By separating loads such as lights in study rooms and desktops, energy demand can be more accurately estimated, improving system efficiency and minimizing downtime.

Reliability planning: Incorporating battery autonomy for multiple days ensures continuity of supply during Bogotá’s cloudy and rainy periods.

Benchmarking with LCOE: The Guajira project’s Levelized Cost of Energy calculations provide a practical framework for stress-testing SolOptimize against current grid electricity charges.

Scalability: The tiered system design in Guajira shows how PV installations can expand as demand grows, a valuable precedent for Children’s Town’s anticipated growth.

Community involvement in maintenance: Long-term sustainability is enhanced when system users are directly engaged in basic upkeep and monitoring.

In short, the Guajira project acts as both a methodological and strategic blueprint, equipping SolOptimize with proven approaches to system sizing, cost evaluation, and long-term viability.

Upon our recent discussion with the client, the focus is majorly on solar photovoltaic systems, and the solar thermal system just needs a preventative maintenance checklist and schedule, which we will be obtaining based on the requirements of the specific boiler systems used at the site.

The solar irradiance angle of the solar panel, or the incidence angle of the sun's rays onto the panel surface, is one of the most significant factors that influence its efficiency of power generation. Ideally, when the sun’s ray angle with the panel surface achieves 90 degrees, which means the panel surface is perpendicular to the sun rays, the solar panel achieves the optimal instantaneous power generation performance [1]. In other words, when the angle of incidence between the surface normal and the sun’s rays reaches 0º, the direct irradiation received by the panel maximizes. Along with the direct irradiation, there are more components like diffuse irradiation and ground reflected irradiation, which are both affected by the intensity of solar radiation received outside the atmosphere, atmospheric clearance factors, position of the sun in the sky, etc. 

Theoretically speaking, for the photovoltaic (PV) system to achieve the best performance, a continuous sunlight tracking system has to be used where the PV system has to constantly adjust its tilt angle according to the position of the sun in the sky; however, we will have to look at the return on investment for the sun tracking technology as it’s relatively expensive. Further, research done in Turkey has shown that a real-time tilt-angle-adjusting system is rarely used outside lab scenarios due to its high initial investments and maintenance costs [2]. Instead, monthly or seasonal adjustments of tilt angle are frequently used because of their economic advantages. Therefore, when our team moves onto the next stage of generating solutions, the tilt angle adjustment is one crucial aspect to consider for a design with optimal performance and cost-effectiveness.

The Children’s Town is located in Bogota, Colombia, with location coordinates of 4°35'26.4"N 74°03'50.6"W. A brief solar and weather description of this location is shown below.

Fig. 2.1. Solar Irradiance Components in Bogota [3]

Fig. 2.2. Solar Azimuth Angle in Bogota [3]

Fig. 2.3. Average Annual PV Power Potential in Bogota [3]

Fig. 1 shows the solar irradiance components, and Fig. 2 shows the solar azimuth and elevation angles in Bogota. This data is helpful for the team in determining the optimal solar panel orientation and its incident angle. Specifically, the following two equations can be used to calculate the Global Tilted Irradiation at optimum angle [4][5].

GTI opta = DNIcos + DIF + DHI 

cos= cosZcos+ sinZsincos(s-)

where   GTI opta: Global Tilted Irradiation at optimum angle

DNI: Direct Normal Irradiation

DIF: Diffuse Horizontal Irradiation

DHI: Ground Reflection Irradiation

θ: Incident Angle

Z: Solar Zenith Angle 

β: Tilt Angle

𝛄s: Solar Azimuth Angle

𝛄: Panel Azimuth Angle

In addition, Fig. 3 shows the Long-term average of annual totals of PV power potential in Bogota, which is approximately 1300 kWh/kWp/year. It means that for every 1kWp of installed PV system, the system generates 1300 kWh of electricity in one year. This data can be useful in determining the required installed capacity(kWp) given the annual energy(kWh) needed at the Children’s Town.

Moreover, Fig. 4 and Fig. 5 below show the historical climate data and wind speed data of Bogota, respectively. This crucial information about the service environment allows the team to generate designs that are durable and suitable for the Children’s Town in Bogota. For instance, the solar panel mounted on top of the roof has to withstand the local rainfall and wind speed, and remain in good working condition. 

Fig. 2.4. Historical Climate data of Bogota from 1991 - 2021 [6]

Fig. 2.5. Wind Speed data of Bogota in 2024 [7]

3.0. Project Requirements

3.1. Functions

The main functions of this project are presented in 3 main parts. These have been broken down as per the minimum requirements, bonus requirements, and preparedness for future situations when faults may occur due to equipment wear and tear. Following the primary functions are the secondary functions that direct our methodology path for achieving the primary functions. 

3.1.1. Primary functions

Minimum requirements: 

Produce enough solar power to power 6x32W bulbs and 15x110V power outlets to charge 15 desktop computers simultaneously in the main study room, with each computer utilizing 100-127V at 8A. 

Bonus requirements (if constraints permit):

In addition, if constraints allow, a bonus function is to produce enough solar power to power an extra 8x20W light bulbs for the dormitories and adjoining restrooms and/or power the adjoining extra two classrooms operating with a total of 12x32W light bulbs - both in addition to the minimum power requirements of the main study room. 

Future preparedness: 

Make troubleshooting and maintenance user-friendly to prevent/fix any future systemic faults with the newly designed system, and for an existing, newly repaired solar water heating system that heats water from a 500L tank.

3.1.2. Secondary functions

Applicable to both - the minimum requirements and the bonus requirements:

Allow the system to switch over to the alternative existing grid system in cases of solar downtime

Provide a battery system to store extra unused solar energy produced during the day for use at night or when there’s not enough solar power to accommodate needs. 

Provide parallel connections from the main study room to the additional spaces if constraints permit, to allow for the power to be supplied as specified above.

Future preparedness:    

Prepare a guide to troubleshoot errors and guide maintenance for the newly designed solar panel system and for the existing solar water heating system. 

3.2. Constraints

3.2.1. Financial

The total cost of the system, including panels, batteries, inverters, and other equipment, must stay within a total budget of CA$10,000.

3.2.2. Roof Capacity

Panels can only be installed on the approved dormitory and study room roofs. While these roofs are confirmed to be structurally safe, the available area limits the number of panels that can be installed.

3.2.3. Operational

The system must never result in an electric malfunction, especially in cases when there is not enough solar power to power the targeted spaces. 

3.2.4. Environmental

Bogotá has variable cloud cover and solar density throughout the year, so the system we design must be able to handle any environmental fluctuations.

3.2.5. Safety

As the facility houses children, the system must follow strict electrical and structural standards to prevent accidents, as well as have some type of child-safe and tamper-resistant design.

3.3. Objectives

3.3.1. Reliability

The solar panel system should “efficiently” provide power to meet the minimum requirements as stated in the functions and any bonuses we cater to. The solar panel system should “seamlessly” allow shifting between the solar panel system and the local grid network. The solar panel system should have minimal downtime in terms of power supply, and thus should be able to charge the backup battery enough to compensate for the same. 

3.3.2. Optimization

The system should generate and store energy as efficiently as possible within the budget and space limits (refer to Section 3.2). If resources allow, it should also be optimized to power two additional classrooms and/or three dormitories.

3.3.3. Affordability

The design must be affordable enough for Children’s Town to be able to set it up, as well as be able to maintain it in the long term.

3.3.4. Maintainability

Maintenance and troubleshooting for the new solar system should be highly user-friendly and seamless to follow if given a guide. This applies to the new solar panel system, as well as to the client’s request for a maintenance guide for the existing solar water heating system.

3.3.5. Sustainability

The system should be designed for long-term use, requiring minimal repair and/or parts replacement over time, and thus reducing the design’s dependence on materials sourced from the environment to produce the spare parts. 

3.4. Stakeholders

RJI (Facility Managers): Clients managing the facility benefit from lower energy costs and oversee future maintenance and upgrades.

Children’s Town Residents: Directly impacted; gain from redirected funds but may face access limits during installation or disruptions if failures occur.

University of Toronto and SolOptimize (us): Main funder (UofT); benefits from cost savings and visible social impact, with potential to redirect funds, reputational credibility advantage for a successful solution.

Suppliers and Maintenance Contractors: Suppliers provide equipment, warranties, and technical support, while contractors handle preventive checks and repairs to ensure long-term reliability.

Donors: Expect measurable improvements in children’s lives and efficient use of contributions.

Government Bodies: Provide subsidies, enforce regulations, and certify compliance. Future policy shifts (renewable incentives, carbon targets) could strengthen or challenge project sustainability.

Environment: Gains from reduced carbon footprint; life-cycle impacts of maintenance must be considered.

Electricity Grid Utility: Faces reduced demand but remains relevant as a backup supply.

3.5. Service environment

As shown in Figure 3.5, the dormitory building consists of three dormitories, each with an area of 36m2. One study room and two additional classrooms are located south of the dormitory building, each with an area of 30m2. The dormitory is 15 meters apart from the closest study/class room. The buildings are built of concrete, and their roofs are strong enough to support solar panels.

Fig. 3.5. Aerial view of the dorms and some of the study rooms

In addition, a summary of the weather conditions of the service environment is shown below:

The maximum temperature is 18℃ and the minimum temperature is 9.4℃. Most of the rainfalls (precipitation) in Bogota happen in Winter and Spring, from October to May, with a maximum precipitation of 152mm per month. The humidity ranges from 67% in August to a maximum of 84% in November. In addition, in 2024, the strongest wind in Bogota had a speed of 65km/h. This data will also be crucial in the solutions stage, as the team’s design must remain functional and durable in all weather conditions of the service environment. 

4.0. Project Plan and Resolution: 

Our team will analyze the location remotely based on the landscaping details provided to us by the client. Based on this, we will evaluate the optimal location to utilize for the solar panels (i.e. on the roof, on the ground, etc.). We will also factor in safety concerns, as the area is housing children. After consulting the client based on the factors they would like to consider, we will evaluate the tradeoffs of placing the solar panels in one location vs another. 

We will also consider sun-tracking modules; however, given our current speculation, the return on investment for the sun-tracking modules may not justify the cost.

All of this will be done after evaluating the sun's position and atmosphere throughout the day, throughout the year, to ensure we fabricate a solution with maximal optimization. This will be done by looking at the variables: DNI, DIF, DHI, θ, Z, β, 𝛄s, 𝛄. These have already been defined in section 2 of this document. 

We will use worst-case scenarios to define the technical requirements of our solutions. 

Lastly, we will suggest a solution that minimizes tradeoffs between factors like solar optimization, cost, safety, etc. We will also ensure the solution adheres to the constraints, and maximizes the objectives while ensuring to meet the required functions. 

In order to facilitate a successful project, our team has set up weekly check-ins with the client to ensure we’re all on the same page in terms of project expectations and solution development. Regular meetings will be required depending on the requirements of the major stakeholders and when we require further details. 

5.0. DfX and human factors

The design of the solar-powered system must balance technical performance with practicality, safety, and long-term usability. Since the installation site is a residential space for children, usability and maintenance cannot solely rely on assumptions, and both the system design as well as documentation must account for who will be interacting with the system and under what circumstances.

5.1. DfX principles

5.1.1. Design for safety

This is prioritized due to the presence of children at the facility. All electrical components must be installed to eliminate shock, fire, or any electrical hazards. The wiring will be enclosed, the panels securely mounted, and the access restricted to authorized staff.

5.1.2. Design for cost-effectiveness

Given the CA$10,000 budget, all design decisions must deliver optimized results in terms of savings that overcome the initial costs. In other words, the return on investment by the facility must break even with the initial costs as soon as possible. 

5.1.3. Design for manufacturability and assembly

The system will use standard, market-available components that are easy to assemble, install, and replace without requiring specialized tools or costly expert consultations.

5.1.4. Design for maintainability

Routine maintenance and troubleshooting must be straightforward for on-site staff to ensure efficient operations. The components will be positioned for easy access for staff, and a clear maintenance manual will be provided to reduce dependency on external workers.

5.1.5. Design for reliability

The system must provide consistent power throughout varying solar conditions. This includes selecting durable components, connecting load-appropriate capacity holding batteries, and having a grid-switching mechanism.

5.1.6. Design for sustainability

By installing renewable energy and durable components, the design will reduce long-term waste and environmental impact while also lowering operating costs for the facility.

References

[1] PVsyst, “Backtracking strategy: Cosine effect,” PVsyst, accessed Sep. 2025. [Online]. Available: https://www.pvsyst.com/help/project-design/shadings/backtracking-strategy/cosine-effect.html

[2] S. Hossain, M. Hasanuzzaman, M. A. Islam, and C. Mekhilef, “A review on solar photovoltaic panel orientation & tilt angle optimization for maximum solar energy utilization,” Renewable and Sustainable Energy Reviews, vol. 162, 2022, Art. no. 112494. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S1364032122006542

[3] Global Solar Atlas, “Global Solar Atlas,” accessed Sep. 2025. [Online]. Available: https://globalsolaratlas.info/

[4] European Commission, Study on small-scale turbines in the European Union — Final report, Publications Office of the European Union, 2025. [Online]. Available: https://publications.europa.eu/resource/cellar/4ef8c4e1-4397-4e27-8487-448786327f27.0001.01/DOC_1#

[5] NASA LaRC, “Energy fluxes on tilted surfaces,” POWER Project, NASA, accessed Sep. 2025. [Online]. Available: https://power.larc.nasa.gov/docs/methodology/energy-fluxes/tilted-surfaces/

[6] “Climate data — Bogotá, Colombia,” Climate-data.org, accessed Sep. 2025. [Online]. Available: https://en.climate-data.org/south-america/colombia/bogota/bogota-5115/

[7] “Historical Weather during 2024 in Bogotá, Colombia,” Weatherspark, accessed Sep. 2025. [Online]. Available: https://weatherspark.com/h/y/23324/2024/Historical-Weather-during-2024-in-Bogot%C3%A1-Colombia#Fig.s-WindSpeed

[8] Vides-Prado, A., Camargo, E. O., Vides-Prado, C., Orozco, I. H., Chenlo, F., Candelo, J. E., & Sarmiento, A. B. (2018, February). Techno-economic feasibility analysis of photovoltaic systems in remote areas for indigenous communities in the Colombian guajira - sciencedirect. ScienceDirect. https://www.sciencedirect.com/science/article/abs/pii/S1364032117307396