ECE 4901 Fall 2020

Developing Electrical Systems for iLoo Facility

Team Members: Austin Caracciolo (Electrical Engineering) Tyler Rourke (Electrical Engineering) Rudy Zhang (Electrical Engineering)

Sponsor: Richard Davids Contact: [email protected]

Advisor: Professor Liang Zhang Contact: [email protected]

Abstract: Team 2123 has been tasked with developing a portable , designed with electrical systems that competitors do not have. The components included in the design include a monocrystalline solar panel, charge controller, absorbent glass mat (AGM) battery, inverter, a lighting and ventilation system, a charging station, and a liquid level sensor. This design should work anywhere in the United States as estimates show our design using less energy than it will draw daily. However, this design is constrained by a limited budget, size allocations, and weathering requirements. Overall, our design accounts for all these difficulties and optimizes all aspects based on what we have available. In order to achieve this goal, we worked with the Civil and Environmental Engineering team (CEE), as well as the Management and Engineering for Manufacturing team (MEM). While the CEE and MEM team focused on different parts of the , the Electrical and Computer Engineering team (ECE) focused on the electrical aspect of the system. We designed the system to achieve the desired performance, while maintaining structural integrity and keeping in mind the budget constraints.

Table of Contents: I. Introduction 5 II. Problem Statement 6 A. Statement of Need 6 B. Preliminary Requirements 6 C. Basic Limitations 6 III. Proposed Approach and Design 8 A. Solar Panel 8 B. Charge Controller 9 C. Battery 9 D. Inverter 10 E. Lighting & Ventilation System 10 F. Charging Station 11 G. Waste Detection System 11 IV. Project Management 12 A. RACI Chart 12 B. GANTT Chart 12 V. Summary 13 References 14 Appendices 15

Figures & Tables:

Figure 1: Solar Irradiance Map of the United States[6] ​

Figure 2: Lighting and ventilation[7] ​

Figure 3: Basic Electrical System Block Diagram

Figure 4: Arduino and Raspberry Pi connection diagram for liquid sensor

Device Estimated Daily Power Usage

Lighting System (5 Watts / Hour when 16 Watt-hours active + 1 Watt / “Standby Mode”)

Ventilation System (6 Watts / Hour) 144 Watt-hours

Charging Station (Three Devices Fully 16.35 Watt-hours Charged)

Waste Capacity Sensors 48 Watt-hours

Sanitation System 58 Watt-hours

Total: 282.35 Watt-hours

Table 1: Estimated Daily Power Usage

Glossary: AGM Battery Absorbed glass mat battery that contains a special glass mat separator that wicks the electrolyte solution between the battery plates Photoelectric The emission of electrons when electromagnetic radiation, such as light, hits a material to detect the distance from the transmitter Powercap An encasement that holds all of the power system components, such as the charge controller, battery, and inverter PWM Pulse Width Modulation, which allows for the conversion of analog signals to digital Ultrasonic Detection system that uses sound waves above the upper limit of frequencies that can be heard by the human ear Qi Qi is a standard for wireless energy transmission and it aims to standardize wireless charging across all devices the same way Bluetooth standards standardize data transmission across all devices

I. Introduction: The purpose of this project is to design and construct a human waste containment system that contains other amenities that similar facilities do not. For the electrical engineering portion of the project, we are tasked with implementing power equipment to create a system that improves the overall user experience. Some of the systems we intend on implementing involve a solar panel charging station for electronic devices, a lighting and ventilation system, and a system to determine when the human waste must be removed from the facility. These facilities are designed with a limited lifespan in mind, specifically one year maximum. It must also be an extremely low cost design with low levels of maintenance and simple construction. We must also be cognizant of the fact that these facilities are intended for use in impoverished communities where they may not have easy access to basic necessities. The facility must act as a reliable space intended for anyone to use. During the design development, some problems our group faces involve making sure our designs receive enough power to act periodically throughout the average day and withstand whatever weather conditions it may be placed in. Some issues also occur like cost management, as well as system complexity. Also, we must work in collaboration with the civil and environmental engineering groups to make sure our designs fit within the constraints of their structure schematics as well as ethical constraints such as environmental sustainability.

II. Problem Statement Statement of Need: The overall design specifications of an iLoo toilet make it a cheap alternative to other laboratories and provides unique amenities that others in the market do not. In fact, based on the information provided by the sponsor, the iLoo toilet is expected to cost under $1,000. It requires low maintenance, and has rudimentary assembly and disassembly. The assembly should make it possible to sell a modular design that the consumer can put together easily on their own. However, the main focus for our design project is what iLoo has and the rest of the competition does not: a solar powered charging station and a waste capacity detection system. Similar to UPS trucks, previous designs have been installed with plexiglass ceilings to allow for daylight to illuminate the inside of the portable toilet. However, in order to light up the interior at night, an lighting system needs to be installed. The included lighting system will be a two-in-one lighting and ventilation system. The purpose of the two-in-one system is to encourage simplicity as well as compactness. The ventilation system would allow for active ventilation, and will be paired with ventilation slits for passive ventilation as well. In order to generate the power required to power the LED needs to run overnight, a singular solar panel is required and will be installed on the roof. The solar panel itself is monocrystalline and will be included with the electrical subsystem along with a lithium ion battery. The electrical system will include wiring, a charge controller, absorbed glass mat (AGM) battery, and an inverter. The total power output is estimated to be around 100 watts with operational efficiency at 2-3 amps on a cloudy day. With the remaining power, our other big task is to develop other systems that will make the experience more enjoyable. This may include adding systems that focus on odor removal and sanitization as well as a user detection system.

Preliminary Requirements: This project will require us to create a subsystem wiring diagram, load analysis, and estimate the output of the solar panels and storage capacity of the battery. Previous knowledge will be used as well as resources provided by the sponsor and advisor. The internal components of this circuit must be housed in materials that are weather and vandalism resistant. Electrical softwares will be used with past experience and online resources. After a system is designed to meet the basic requirements of a charging station, adequate lighting and ventilation, and a waste capacity sensor, other systems may be added to improve the user experience.

Basic Limitations: Based on our conversation with the sponsor, one of the biggest initial limitations involves the size of the solar panel. Depending on the specifications of the civil engineering group’s initial plans for the facility, there may not be enough space for a larger solar panel. Therefore, it is imperative to our design that we coordinate an area in which the solar panel can reside. Also, since our designs will have a finite space to work with, we must optimize the amount of energy we can harness given whatever size solar panel we are able to obtain. Environmental sustainability must be considered when doing the design, and it also has to follow all legal guidelines. The total solar energy generated is another limitation of our system. The amount of energy that we are able to generate for the facility will dictate the amount of electrical systems that can be added. This means that we may not be able to add as many electronics as desired or any power intensive components. Unfortunately this constraint only worsens as we also need to accommodate for varying weather conditions. iLoo may be placed in various locations within the United States or in more rural areas of other countries such as India, as it’s designed to be cheap and consumable. Another area of focus our group needs to keep in mind when selecting components is to focus around cost. Since the average cost of a iLoo facility, at minimum, is about $1,000, we must minimize the cost of the components used while designing the systems. The sponsor did not directly constrain the financials of our portion of the project, however, since these facilities are expected to only last one to two years, we should not use considerably expensive equipment. Not to mention, these facilities may be used in places such as rural areas of the United States and India, so some of our components will be exposed to varying weather conditions. This ultimately means that our components must be specialized to endure various types of conditions and climates with humidity being one of the biggest concerns. As our sponsor had told us, we must keep the prices low and the efficiency high. One big factor that must be considered when making the design of the iLoo is vandalism. Thieving may not be big in every culture, but it is definitely something that is an issue in American culture, as anything expensive left out has a high chance of getting stolen. The design of the toilet needs to be made to be resistant to any sort of vandalism. Finally, the waste management system is one of the biggest factors that will differentiate the iLoo from any regular Porta Potty. The design of the waste system will include two offset 55-gallon drums. The two drums will be connected to each other, and the main purpose will be to separate the solids from the liquids. This mitigates the ammonia smells, and will minimize the overall stench of the toilets. Multiple designs were created to detect the maximum capacity of the waste. The reliability of each design was considered, and the one with the least limitations on our system was chosen. A simple photoelectric liquid detection system was chosen as it would be the most efficient and reliable when compared to a force-sensitive resistor or an IR beam. Although a photoelectric liquid sensor wouldn’t work as well as ultrasonic sensors or magnetic float sensors, it is the cheapest option by a long shot. With the photoelectric system, we can rely on the improved sensitivity as anti-corrosive components.the sensor will be connected to a system that will send a signal to an arduino and GPS module (enclosed) for when it needs to be maintenanced. III. Proposed Approach and Design: Solar Panel: In order for our group to develop any designs for the system, we needed to understand each component that will be used. The first component our group researched was the solar panel. In our initial meeting with the sponsor of the project, our goal was to select a panel that has the most efficiency with a smaller relative size. Once it was determined, with the help of the civil engineering group, that the facility would be at least 48 inches by 48 inches, we could research the market and determine the best fit. We decided that our design will feature a monocrystalline solar panel. We chose this over the competitor, polycrystalline solar panels, because monocrystalline panels are significantly more efficient. Based on our research, this is the case because since monocrystalline solar panels are composed of just one silicon crystal per cell, the electrons are able to move more freely and generate more electricity. This is compared to the polycrystalline panels, where they are manufactured by melting many fragments of silicon to form the cells. Estimates show that monocrystalline solar panels have efficiencies anywhere from 15 to 20 percent versus 13 to 16 percent from polycrystalline panels. On top of being more efficient, monocrystalline solar panels are more expensive. Although with solar panel technology advancing, more and more solar panels are available at cheap prices. The solar panel we have decided to use is 100 Watt, 12 volt panel and is monocrystalline as discussed earlier. The panel is less than 4 feet by 2 feet, which fits well on the roof of the portapotty. Another benefit of the chosen solar panel is that it is very weather resistant, with the ability to withstand 2400 Pa of wind force and 5400 Pa of snow. In order to make sure that our preliminary system design would have enough power, our group investigated the amount of sunlight hours across the United States. We presumed that if the areas with the least amount of sunlight hours would generate enough electricity, even on days with less than desirable conditions, then our system should work everywhere else in the United States. For reference, the sunlight hours were quantified as the power per unit area received from the sun. Based on the solar irradiance maps from the National Renewable Energy Lab (NREL) in figure one the area of the United States that had the least amount of sunlight hours was Seattle, Washington with 3.3 to 3.9 peak sunlight hours. Multiplying the hours with the voltage rating of our solar panel, our design should expect to obtain anywhere from 330 to 390 watt-hours of energy daily. Based on this information and the table one, our entire system will use less than what will be generated daily.

Charge Controller: When researching what components are needed in order to use a solar panel as our energy source, a charge controller was necessary. Charge controllers are added to solar panel circuits to regulate the voltage and current to keep the battery from overcharging. While not necessary for some solar panel circuits with low outputs, since we expect to charge multiple phones and provide adequate lighting and ventilation we cannot use low power panels. Also, while researching the different types of components, our group found three different categories of charge controllers. The first of which was the Simple 1 or 2 stage controls which depend on relays and shunt transistors to control the voltage. While these are antiquated systems, 1 or 2 stage controllers are still used today because of their reliability. The second major category is 3-stage or pulse width modulation (PWM) charge controllers. In circuits involving solar panels today, PWM charge controllers are the norm. These controllers slowly reduce the amount of power going into the battery as it reaches capacity. When the battery is full, the controller will constantly supply a “trickle” of power to the battery to continuously make sure the battery is at maximum capacity. The third and final charge controller is the maximum power point tracking (MPPT) controller. While these controllers appear to have the best efficiency compared to the other categories ( 94 to 98 percent efficiency), they also come with the expensive price point. These MPPT controllers can pair the different voltages of the panel and battery to adjust the input and bring the maximum amount of power to the battery as quickly as possible. Unfortunately, while these controllers would be great from an engineering standpoint, the price point of the typical MPPT controller is out of the project’s budget. The charge controller we chose is a pulse width modulation controller due to the fact that they work well with solar panels and have a cheaper price point, which is very crucial to our project at this point. We were able to find a package deal of a solar panel and a charge controller that is rated at 30A, as the solar panel is rated at 29A. Using a package deal allows us to save even more money. The controller is rated at 400W, which safely accommodates our system. Battery: The main purpose of this battery is to provide charge for the entire electrical system. It will take the 12V output from the charge controller and store the charge for the electrical system. The battery will provide charge for the charging station, lighting, and the waste detection system. Since everything is heavily reliant on the battery functioning, it must be extremely reliable and theft resistant. The battery will be enclosed in the power cap, so it will be protected from weather and tampering. In our case we decided to use an AGM battery as opposed to something like lithium ions batteries. There are pros and cons to both types of batteries. Lithium Ion batteries have a better depth of charge, allowing around 86%-89% discharge while lead acid batteries like AGM can only handle around 30%-50% discharge. Another benefit of the lithium ion battery is a longer lifespan, which isn’t too much of a problem for us because the porta potties are planned with a shorter lifespan of around one year and an AGM battery will last much longer than that. The main reasons that AGM batteries are better for solar and our application is because they require no maintenance and have very low chances of spilling or breaking open due to corrosion. Overall an AGM battery is a very safe and cost effective way to run electronics for long periods of time. The solar panel and charge controller are able to charge the battery at a rate of 8.33Ah per hour in ideal conditions. Originally, we planned on using a 100Ah battery, which would be fully charged in 12 hours of ideal conditions. A 100Ah is enough to run all of electronics for nearly 9 days at full consumption estimates. Although we decided to use a 35Ah battery to save money, which would fully charge in 4hr and 15min of ideal conditions and could hold 3 days of charge. Inverter: In order for the lights, ventilation, charging system, and waste detection system to operate they need an AC power. The purpose of the inverter is to convert the 12 VDC voltage input produced by the solar panel, stored in the battery, and converts it into 120 VAC. This inverter provides 600 Watts of pure sine wave power which will be plenty enough for the parts we have chosen to run on it. The inverter chosen will have an internal cooling system to prevent overheating, especially in hot climates. The inverter is also very light weight. The inverter is the most expensive part of our power system. It is important for us to get a reliable inverter that does not have untrustworthy components in it because it is a complicated system that if it goes wrong, then the rest of our components or even the entire porta potty can get destroyed. Originally we had planned to use an inverter with GFCI ports in order to protect the inverter from the weather, but that had to be cut due to budget constraints. This shouldn’t be a problem because the inverter and the rest of the powercap are going to be encased in a sort of ‘suitcase’ of metal to protect it from weather and theft. We are considering selling the portapotty with some of the higher end electronics at a larger price point, such as the GFCI inverter and a 100Ah battery. Lighting & Ventilation System: The lighting and ventilation system will be a two-in-one design. With some research, our team was able to find a solar ventilation system with three LED lights. The purpose of the solar panel is to relieve our design of the high power consumption of the lighting system. With the two-in-one design, we encourage compactness and simplicity. With this design, we would be able to save a lot of room for other electrical components. We looked into the SVL-408AR, which is a two-in-one lighting and ventilation system, as a basis for our design. An idea that may be implemented is including a cut-out designed for the lighting system that allows for the consumer to decide on whether or not they want to include this subsystem. The lighting system must be bright enough to light up the entire room for visibility, and preferably no strobing lights. The concern with this two in one design is that we are worried about the reliability of both the ventilation and lighting system. We are worried that the efficiency of either systems will be bottlenecked 3 by one another, but the ventilation system will work at an efficiency of 1000 ft .​ When ​ talking about the cubic volume of the iLoo system, a 4’x4’x6’ system will stay well ventilated. Active and passive ventilation will be implemented for more air flow and odor removal. Charging Station: After our initial meeting with the sponsor, he told us that he would prefer that the user has access to a charging station both inside and outside of the facility. That way, the user is not forced to sit for prolonged periods of time inside and may allow someone else to simultaneously use the portapotty for its intended purpose. In our conversations we also determined that it would be beneficial to include both wired and wireless forms of charging. With the charging station, we are going to provide a limited amount of universal chargers that will be theft-proof. With the universal chargers, there will be charging ports included in the case anyone brings their own chargers. All the charger ports must be reliable and weather resistant, otherwise they won’t perform efficiently without the right conditions. With any type of charging station, the speed of the charging is very important, as we don’t want users to stand at the portapotty all day charging their devices. Ideally, a super charger will be implemented for a sped up charging time. When we were first discussing charging, we thought that it would be inefficient to include charging on the inside as only one person will take up all the charging capacity. Keeping charging ports on the outside only doesn’t work too well either because then you won’t be able to use the and charge your device like intended. The solution to this issue is to add a charging station on the inside and outside. This would leave no incentive for the user to stay inside the iLoo just to charge their phone. One thing to consider about charging is wireless capabilities. Wired charging has been around since the beginning of devices, but new Qi wireless charging is becoming more popular in modern society. With wireless charging, we get increased reliability with electrical fault protection, as well as better durability. The exchange of this is that we get a 15% slower charging speed, which is very important for common consumers. Waste Management System: A photoelectric liquid level sensor was chosen as seen in Figure 4. The sensor will connect to an arduino which will send a signal to an enclosed GPS module. The photoelectric liquid sensor was chosen over a magnetic float sensor and ultrasonic level sensor mainly for cost reduction. During the initial research, a magnetic float sensor or ultrasonic level sensor seemed ideal for our usage, but it was not financially viable. With this being said, a simple photoelectric sensor was chosen. The photoelectric sensor has great sensitivity as well as corrosive resistant components. The accuracy of the product is considered, and the placement of the component will be specific to the design. The biggest limitation for the waste detection system is the reliability of the separation system. If the system gets clogged too early or it doesn’t separate properly, then there will be overflow in the waste system. IV. Project Management: RACI Chart:

During our team’s meetings, we discussed what would be best in order to fully understand the scope of our portion of the project and stay on track with our deadlines. When drafting this RACI chart, one of the most important things we kept in mind was an equal distribution of the work. That way, each team member had a dedicated portion to research themselves and return to the group when they believed they had an appropriate solution to the task. Therefore, researching the components for a charging station, waste management system, and lighting system were all separated as those were the biggest components we needed to add to our design. Based on the labels of our RACI chart, the sponsor was aware of the progress our group has made on each system and approved the publishing of the project statement on the project website. Unfortunately, since our group has not determined the final components list for our design, a budget is not available at this time. However, as we continue to work with the other groups we are able to get a better understanding of the dimensions of the facility. Once the other groups determine the size for the facility we may proceed in determining which components will work best. Gantt Chart: The Gantt chart above shows the estimated timeline our group has been following to stay on course with project deadlines. The research and website design are consistent as they were constantly worked on throughout the semester. The other deadlines shown in the figure involve the project statement, review presentation, project proposal and final report. One extra set of deadlines our group had to meet involved presentations to the other design groups and sponsor. This made sure that the groups were constantly making progress on the design, and allowed the sponsor to approve the direction the project is heading.

V. Summary: While there were many additional designs that were considered for the iLoo, we decided to focus on the main issues that differentiated it from a standard PortaLoo. The main focus on the iLoo was the solar panel, which is what powers our entire electrical system. Given the restraints and limitations of our design, we were able to come up with the minimal requirements that we will need for the solar panel. From there, we must include an inverter to change the solar panel’s DC input to an AC, which will then charge the battery. For the battery design, we chose a battery that is reliable and efficient. It must charge all of our components, and hold enough charge to power the electronics when there is no sun. There will be one main lighting system, that will also include a ventilation system. The two-in-one solar lighting and ventilation system can be reverse engineered to connect directly to the battery and be powered by that instead of the small solar panel that comes with the light and ventilation system. The battery will also provide power for the charging station on the inside and outside of the iLoo. The reason that we chose inside and outside was because in case someone took too long inside, people could actively charge their phones using the outside cables/ports. A fast charging station will be utilized in order to charge devices as fast as possible, to prevent user buildup around the iLoo. This allows the users to efficiently charge their devices, and it limits the amount of time spent at the charging stations. The charging station should be able to charge three devices at once, and this is only possible if the capacity of the battery is large enough to handle all the charge. Finally, a waste management system will be implemented in order to detect when the waste storage is at full capacity. The system must be as reliable as possible, with minimal error. This means that all the limitations of this system must be considered within this design. One major issue that is still proving to be difficult is the method of separating the solids and liquids. The main tube that connects the two half-drums must not clog. A magnetic detection system will be used, and the way it works is a magnet will move up/down based on the liquid level and when it gets a certain point, it will flip a switch. This will then send a signal to a raspberry pi connected to a GPS module that is enclosed. A signal will be sent to the maintenance company indicating that the waste system is at maximum capacity.

References:

[1] “Portable​ Toilets: Waste Management.” Portable Toilets | Waste Management, ​ ​ www.wm.com/us/en/business/portable-toilets.

[2] Rose,​ C, et al. “The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology.” Critical Reviews in ​ Environmental Science and Technology, Taylor & Francis, 2 Sept. 2015, ​ www.ncbi.nlm.nih.gov/pmc/articles/PMC4500995/.

[3] “​ FAQ's.” The Portland Loo, 4 June 2020, portlandloo.com/faq/. ​ ​

[4] Mohankumar,​ D. “Solar Charger Circuit for 6V Battery.” Electro Schematics, 24 ​ ​ Mar. 2014, www.electroschematics.com/solar-charger-circuit/.

[5] Norhter​ Arizona Wind & Sun. “Solar Charge Controller Basics.” Northern Arizona ​ Wind & Sun, 2020, ​ www.solar-electric.com/learning-center/solar-charge-controller-basics.html/.

[6] ​ National Research Energy Laboratory. “Solar Resource Data, Tools, and Maps.” NREL.gov, 2019, www.nrel.gov/gis/solar.html. ​

[7] ​ “Solar Ventilation Fan with Battery.” Sundance Solar, 2020, ​ ​ store.sundancesolar.com/solar-ventilation-fan-with-battery/.

Appendices:

Senior Design Project Checklist

Project name: iLoo ​ Sponsor: Richard Davids ​ Team members (majors/programs):

Austin Caracciolo (Electrical Engineering) ​ Tyler Rourke (Electrical Engineering)

Rudy Zhang (Electrical Engineering)

Faculty advisor(s):

Professor Liang Zhang ​

Skills, Constraints, and Standards: (Please check (√) all those that apply to your ​ project.) ​

Skills: (√)

Analog circuit design and √ troubleshooting

Digital circuit design and troubleshooting √

Software development/programming √

Embedded Systems/Microcontrollers √ ​

Web design

RF/wireless hardware √ Control systems

Communication systems

Power systems √

Signal processing

Machine shop/mechanical design

Other (please specify):

Constraints:

Economic (budget) √

Health/safety √

Manufacturability √

Environmental (e.g., toxic materials, √ fossil fuels)

Social/legal (e.g., privacy) √

Standards: List standards/electric codes that you If applicable, list the name or # here: used (e.g., IEEE 802.11, Bluetooth, Qi Wireless Charging Standards RS-232, VHDL, etc.) ​

IEEE 1547, 1562, 937, 1013, 1361, 1526, 1561, 1562, 1661, 2030