User:Alka Verma

Overview[edit | edit source]

This document presents the comprehensive final course project undertaken during the Spring 2023 semester for ENGR 535 (Development Technology), a graduate course at Cal Poly Humboldt. Student team collaborated with the Schatz Energy Research Center to develop air quality monitoring technology to deploy in remote, wildfire-affected areas. The objective assigned to our team was to successfully ideate, design, prototype, construct, and test a solar-powered air quality monitoring system for use in off-grid homes. The deployment of this project is expected to take place in Orleans, situated in Humboldt County, CA.

This page contains our final product design, construction manual with video and user manual as well as complete instructions and suggestions for appropriate usage.

Criteria[edit | edit source]

Our criteria and constraints for this project are based on our best understanding of the stated needs of our client. The most important criteria for this system are reliability, durability, and ease of transport. This system must collect PM2.5 data reliably and as consistently as possible. It must be resilient to wildlife and moderately resilient to weather. Finally, it must be relatively easy to collapse and transport in the trunk of a car. The final design will be thoroughly assessed using a series of tests to determine fit to the criteria outlined by the team. The testing and results section of this report will provide information on how the system fits the criteria.

Table 1. Criteria and Constraints

Criteria	Constraints	Weight
Reliability	Sizing: the system must run 24/7/365. Connectivity: must be able to collect PM2.5 data without significant interruptions.	10
Durability	Must be resistant to wildlife, weather, and other external influences.	9
Ease of Transport	Must be relatively easy to transport from place to place in a car.	8.5
Ease of Use	The construction and user manuals must be clear and easy to use. The system must be easy to use.	8
Safety	System must not be a hazard to users during construction or use.	8
Cost	Must stay within budget.	7
Replicability	Easy to replicate/adjust for different projects.	7

Design Description[edit | edit source]

The final design for this project consists of a 30W panel, a 128Wh battery, a 30A charge controller, a DC-DC Buck converter, the Purple Air sensor, and a PVC mounting structure. This system is expected to successfully power the Purple Air sensor 24 hours a day, 7 days a week, and 365 days a year, with expected days of autonomy of approximately 3 days. The physical system is constructed using schedule 40 1” PVC pipe and fittings, assembled using PVC cement. The final system includes a 14.6"×10.6"×5.9" junction box which holds the battery, charge controller, buck converter, and other moisture-sensitive wiring.

A 3-foot USB to micro-USB cord is connected to the charge controller to power the Purple Air sensor. Both the micro-USB and the PV wires inside the junction box are fed through a PG7 cable gland. Additionally, a set of 16 1.5” galvanized metal U-pins serve to stake the base into the ground to ensure structural integrity. Any loose wires are fastened taunt to the PVC mounting structure using high-quality, outdoor-grade zip-ties. Zip-ties are also used to fasten the junction box and PV panels to the PVC frame. A complete list of materials and cost breakdown is provided below.

Materials and Cost[edit | edit source]

• put table for list of materials and cost

Step-by-Step Construction[edit | edit source]

Setup your workstation:[edit | edit source]

1. Gather materials from the purchasing list as well as additional tools needed:
   • Measuring tape
   • Saw or PVC pipe cutter
   • Pencil
   • Extension cord
   • Sturdy surface to cut PVC
2. Clear the workstation from any existing debris.
3. Lay out lengths of pipe, measuring tape, pencil, and saw. Set aside solar components, fittings, and Christy’s PVC Pipe Cement.

Part I: Making the Base[edit | edit source]

1. You will need to cut pipe to the following segment lengths:
   • One (1) segment 22” (F).
   • Four (4) segments 12” each (L1, L2, R1, R2).
   • Four (4) segments 10.5” each (BL, BR, ML, MR).
2. You will need the following fittings:
   • Four (4) 90° elbows
   • Four (4) Tees
3. To ensure all pieces are cut to the correct lengths, assemble (without gluing) according to the diagram below.
4. Congratulations! You’ve assembled the base. Now it’s time to glue the fittings to the pipe using Christy’s PVC Cement.

Part II: Joining PVC Pipe and Fittings[edit | edit source]

1. Gather materials:
   • Cloth to clean pipe/fittings
   • Cloth to wipe excess glue
   • PVC Pipe Cement AKA PVC glue
2. Ensure that both pipe and fittings are clean and free of dust, dirt, excessive moisture, or any other debris. Use a cloth to clean as needed.
3. Before beginning, keep in mind that PVC glue dries up quickly. Read through the instructions carefully before joining your first pipe and fitting.
4. Use the dauber brush attached to the PVC glue container lid to apply a generous layer of glue to the inside of the fitting, without allowing it to puddle or drip, and to the outside of the pipe end, as shown in the images below:
5. Quickly, insert the pipe end into the fitting, twisting the pipe one-quarter turn.
6. Hold the pipe into the fitting for 30 seconds and allow it to dry.

Part III: Making the Panel Mount[edit | edit source]

For 30W panel size: 13 ¾” x 24 ½”

1. You will need to cut the pipe into the following segment lengths:
   • Two (2) segments 6.5” (A1, A2)
   • Two (2) segments 4.5” (B1, B2)
   • Two (2) segments 3.5” (C1, C2)
   • One (1) segment 9.5” (D)
   • One (1) segment 7” (E)
2. You will need the following fittings:
   • One (1) Cross
   • Three (3) Tees
   • Four (4) 90° Elbows
3. To ensure all pieces are cut to the correct lengths, assemble (without gluing) according to the diagram below.
4. You should have now successfully assembled the mount for the solar panel.
5. Time to glue the pieces together following the same instructions in Part II, keeping in mind the following:
   • First, assemble and glue Side 1 and Side 2 separately.
   • Glue piece D and piece E to the center cross-fitting.
   • Glue each side to the center cross one at a time, ensuring to twist according to the directions the fittings must face.
   • Cut four (4) small 2” pieces of pipe and insert them into the elbow fittings for extra support, circled in yellow below.
   • Don’t forget to include the Tee fitting at the top of segment E, circled in white above.

Part IV: Finalizing Assembly[edit | edit source]

1. You will need to cut the pipe into the following segment lengths:
   • One (1) segment 29 ½” (FS)
   • One (1) segment 40 ½” (BS)
2. You will need the following fittings:
   • Two (2) 45° Elbow
3. Cut a small pipe segment (1-2”) to connect the top Tee fitting and the 45° elbow fitting (see below right-hand picture).
4. To ensure all pieces are cut to the correct lengths, assemble (without gluing) according to the diagram below.
5. Glue any remaining part of the system following the instructions in Part II.
6. The PVC mounting structure is now finished!

Part V: Ready for use[edit | edit source]

1. Now that the mounting structure is complete, it is time to bring out the rest of your solar air sensor components:
   • Charge controller and built in battery
   • Solar panel
   • Purple Air sensor
   • USB to micro USB cable
2. Stake the base of your PVC mounting structure with tent stakes.
3. Place the PV panel on the panel mount.
4. Plug in the PV output cable to the charge controller/built in battery.
5. Place the Purple Air sensor under the solar panel and use tape and zip ties to fasten it as needed.
6. Plug the load (Purple Air sensor) into the charge controller using the USB to micro USB cable.
7. Register and connect the Purple Air sensor to local Wi Fi using instructions from User Manual.
8. Check map.purpleair.com to see the real-time air quality near you!

User Manual for Solar-Powered Air Quality Monitoring System[edit | edit source]

Introduction[edit | edit source]

The standalone Purple Air sensor is a device that measures and reports real-time air quality to the Purple Air sensor’s website. This system uses a solar panel, charge controller, and battery to power the Purple Air sensor. The purpose of the user manual is as follows:

1. Provide instructions to install, operate and maintain the standalone air quality monitoring  system.
2. To understand the critical safety features and the system's technical specifications.

Checklist[edit | edit source]

• Solar PV module(30 watts)
• Battery(12.8V,10A,128Wh)
• Purple Air sensor
• Charge controller(24V/12V, 30A)
• DC-DC(12V/5V) buck converter/USB to micro USB cable
• Electrical junction box
• Battery connection wires( 5A fuse for positive terminal)
• Zip ties-various sizes
• Galvanized U pins-1.5”
• Screw driver

Safety Precautions[edit | edit source]

A. Basic safety precautions to follow while installing, operating and maintaining the system:

1. Prevent dropping or impacting the components.
2. Avoid exposing the battery, charge controllers and Purple Air sensor to high heat, dampness, or water.
3. Avoid letting children or pets near the device.
4. Do not clean the sensor with water or other liquids, which may damage it.
5. Do not disassemble the device.

B. Cautions and potential risks

1. If the system stops working, please follow the troubleshooting instructions.
2. Use only the batteries recommended(12.8V,10A, 128Wh) if replacing them is necessary.

     

Features[edit | edit source]

1. The device is portable and simple to install anywhere because it is powered by a 30-watt solar panel and a 128Wh battery.
2. The system uses a Purple Air sensor, which offers reliable information on air quality.
3. The device includes a PVC-based mounting system that enables you to install it on any surface at different locations.
4. The air quality readings can be accessed in real-time on the Purple Air sensor cloud.
5. The system design is robust and thus can withstand high wind speed, snow and other expected local weather conditions.

Installation[edit | edit source]

Installing the solar-powered air quality monitoring system: Step-by-step instructions[edit | edit source]

A. Off-grid solar PV system  installation[edit | edit source]

1. Ensure the area has access to sunlight(south-facing) and is not blocked by trees, structures, or other objects before installing the device.
2. Ensure that the system is installed at a place free from nearby pollutant sources (don’t install near a garage, a gravel road, a fire pit, smoking areas, building exhaust, etc.). Pollutants such as vehicle exhaust, dust from gravel roads, and smoke from fire pits can negatively impact the air quality in the system's installed area. It is recommended to install the system at least 50 feet away from any potential pollutant sources mentioned above.

3. 

   Place the constructed PVC mounting structure on the ground considering the conditions stated in 1 & 2 above, as shown in Fig 1.

4. 

   Fix the 1.5” galvanized U pins across the base of the PVC mounting structure as shown in Fig 2.

5. 

   Take a picture of the device id of the Purple Air sensor, as this would be needed for registration, as shown in Fig 3.

6. 

   Place the Purple Air sensor in the middle of the top of the mounting structure with the help of zip ties, as shown in Fig 4.

7. 

   Place the Solar PV module (30 watts) at the top of the mounting structure, as shown in Fig 5.

8. 

   Fasten the solar PV module using zip ties, as shown in Fig 6.

9. 

   Take the wires from the PV module and the micro USB cable through the PG7 cable connector of the junction box. Connect the red wire from the solar panel to the + terminal  and the black wire from the solar panel to the -ve terminal of the charge controller, as shown in Fig 7.

10. 

    Connect the red wire having a 5A fuse and the black wire to the + and -ve terminal of the charge controller meant for the battery and connect the DC-DC buck converter to the Charge controller “load” terminals as per the polarity( red to the + terminal and black to the -ve terminal) as shown in Fig 8.

11. 

    Place the battery(vertically) and charge controller on the mesh of the junction box using zip ties and place the mesh in the junction box, as shown in Fig 9. Tighten the screws in the junction box.

12. 

    Connect the battery wires from the charge controller to the battery terminal, as shown in Fig 10.

13. 

    Connect the micro USB cable to the micro USB port of the Purple Air sensor, as shown in Fig 11. Check for the red LED; it shows that the Purple Air sensor is ON.

14. 

    Adjust the wire length and close the junction box and place it on the base of the PVC mounting structure, and, using zip ties, fasten it to the base of the structure, as shown in Fig 12.

15. 

    Fasten the wires from the solar PV module and the micro USB cable to the mounting structure using zip ties, as shown in Fig13.

Note: The user may use a USB-micro USB cable plugging the USB cable into the USB output of the charge controller and the micro USB to the Purple Air sensor by using a PG 13.5 or the higher cable connector. We have used a DC-DC buck converter(12V/5V) as we don't have the PG 13.5 cable connectors.

B. Connecting the Purple Air to wi-fi[edit | edit source]

1. Ensure that the LEDs of the Purple Air sensor are ON, as shown in Fig 11.

2. 

   Connect to the sensor's hotspot by opening the network settings on your Wi Fi-capable device (phone, computer, etc.). The hotspot's name will be Purple Air-****, as shown in Figure 14.
3. A popup can show up depending on the Wi Fi-capable device being used. Open a web browser and type "http://192.168.4.1/config" into the address bar if it still does not display. Try momentarily stopping or disabling mobile data on your Wi Fi-enabled device and retyping the URL above if it still does not appear.
4. If the hotspot doesn't appear on a Wi Fi capable device, wait for 10 minutes and try again, as it may take a while for the Purple Air sensor network to appear.
5. If the sensor's Purple Air-**** network is not visible even after 10 minutes of power on, it may already be Wi-Fi-configured.

6. 

   In the popup window or http://192.168.4.1/config page, from the list of accessible networks, choose the one to which you are attaching your sensor. Input the Wi Fi network's password after that and select "Save," as seen in Figure 15. It may take a while for the connection to be established. “Looking Good” will appear at the top of the page after the Wi Fi is established.

C. Registration of Purple Air sensor[edit | edit source]

1. Go to www.purpleair.com/register to register your Purple Air device.
   • First, type in your device-id from the picture you have taken, as shown in installation steps A-5.
   • Type in the email associated with the purchase of the device.
   • Select whether the device is located inside or outside.
   • Name the location where the device is currently located. (like, 879 Union Street).
   • Select Visibility: public (everyone).

   • 

     Set the device's current location by moving the red indicator bubble on the map or typing in the location's coordinates as shown in Fig 16.

• • Skip the Onboard LED Options and Data Processor sections.

  • 

    Fill in the Device Owner’s Information section with the necessary information as shown in Fig 17.

• • Agree to the terms and conditions and click on

  2. Check whether the Purple Air sensor is visible at https://map.purpleair.com.

Operation[edit | edit source]

1. Connect the Purple Air sensor to the power output to turn it ON, as explained in the installation step A-13.
2. The air quality readings can be accessed from the Purple Air sensor cloud https://map.purpleair.com/1/mAQI/a0/p604800/cC0#11.51/40.9042/-124.1  and are represented by different colors.

Based on the US EPA PM 2.5  AQI (Air Now, n.d.)-

• 0–50(Green):  The air quality is acceptable, and after 24 hours of exposure, there is little to no risk from air pollution.
• 51–100(Yellow):  Acceptable air quality. Some individuals, particularly those with an abnormally high sensitivity to air pollution, may be at risk after 24 hours of exposure.
• 101–150(Orange):  After 24 hours of exposure, members of vulnerable populations may develop health impacts. It is less likely that the general population will be impacted.
• 151-200(Red):  After 24 hours of exposure, certain members of the general public may experience health consequences; people in vulnerable groups may have more severe health impacts.
• 201-300(Purple):  Health warning: After 24 hours of exposure, everyone is at higher risk for health consequences.
• >300(Maroon): According to the health warning for emergency conditions, everyone is more susceptible to harm after a 24-hour exposure period.

Maintenance[edit | edit source]

The system requires significantly less maintenance. Still, follow the below-mentioned steps and frequency for the maintenance of the system:

• Check and clean the solar panel- Monthly; Solar panels must be cleaned regularly to ensure maximum efficiency. Clean it with a soft cloth.
• Check data transmission - In case of a Wi Fi outage. The Purple Air automatically connects to the Wi Fi once configured, but it is advised to check when there is a Wi Fi outage to ensure real-time data for the air quality. If there is any problem, then follow the troubleshooting steps.
• Conduct routine maintenance- Every three months; Conduct routine maintenance on the monitoring system, checking the cables and connections and ensuring that the system is securely mounted.

Technical Specifications[edit | edit source]

• Solar Panel-30 Watts
• Charge Controller-12V/24V 30A
• Voltage-12/24V
• Max. PV input power-130W(12V)/260W(24V)
• Battery-12V ,10Ah 128Wh
• Sensor-Purple Air sensor (1.5 watts on 120V AC  and 0.9 watts on 5V DC)
• Energy consumption for 24 hours-36Wh (AC) & 30Wh (based on the discharge test)
• The maximum operating temperature for the system is 60°C(140°F).

Support[edit | edit source]

For any issues and problems related to the air quality monitoring system, try the following troubleshooting steps:

1. 

   Check for the 5A fuse between the charge controller and the battery-positive terminal as shown in Fig 18. If the fuse is blown, replace it with another 5A fuse or proceed to the next step.

2. Check the solar panel for any shading or dust deposits; if any, clean it with a soft cloth (preferably cotton).

3. Check for any wiring issues(i.e. break in wiring).

4. Check the charge controller if the battery voltage is above 11V.

5. Check the sensor connectivity with the Wi Fi (by checking for the sensor over the Purple Air sensor cloud network). If not, follow the steps to reconnect as mentioned above in installation B.

6. If the sensor AQI readings are incredibly high on regular days, check for a nearby pollutant source. If no pollutant is observed, gently wipe the Purple Air sensor with a clean, dry cloth.

• Even after trying the above troubleshooting steps, if the system is still not online, please contact our system support team by
• Email-
• Phone-

While contacting our customer support, please keep this information handy.

• Information about the issue or problem &
• The location where the system is installed

Conclusion[edit | edit source]

The standalone solar-powered air quality monitor system is a valuable device for keeping track of the outdoor air quality index, especially during wildfire and smoke conditions, and thus providing reliable information to the community so that proper mitigation and precaution could be taken to protect them from wildfire hazards. The user should follow the above instruction to ensure the system's satisfactory performance and protect the user from possible hazards. It is a good investment for homeowners and commercial users to observe the air quality and take necessary precautions or mitigation measures for protection from hazardous smoke events, which may cause respiratory illness, cardiovascular illness and other serious health issues.

Warning: Display title "" overrides earlier display title "ENGR 535: Solar Powered Air Quality Monitoring System".