Introduction: Solar Light Street Seats
Street Seats Solar Lighting
Intro & Vision
Each year the The New School, Parsons School of Constructed Environments teams up with The New York City Department of Transportation to participate in the annual citywide Street Seats program. The Street Seats program allows for schools, businesses and organizations throughout the city to design and transform two empty parking spaces into a public seating area. For the past three years the Parsons School of Constructed Environments offers a spring course where students and professors dedicate the entire semester to designing and fabricating the New School’s Street Seat space.
In the Spring of 2017, the Street Seats design team expressed a desire to design a space that was environmentally conscious and utilize alternative materials that created a lighter environmental footprint than traditional architectural building materials. The team decided to build their space from 365 pieces of bamboo and used 75 plant pouches made from recycled water bottles in order to hold the plants within the structure. In addition to fabricating an environmentally friendly space, the team also envisioned incorporating a solar powered lighting system to illuminate the structure in the evening.
In order to accomplish this goal, the team received a donation from Voltaic Systems that gave the team the opportunity to make their vision come to life. Voltaic System provided 15 LED lights, 6 solar panels, 6 rechargeable batteries and wiring in order to power the lighting system. Once the team received this donation, they brought on two graduate research assistants. Jeana Chesnik, a first year graduate student from the Parsons Design & Technology program and Gabi Korac, a first year Parsons graduate student of Architecture and Lighting Design. They teamed up with Mahalakshmi Sivakumar, the Architectural Design design student enrolled in the Parsons Street Seat course that was leading the lighting portion of the project. These three students in addition to other team members created the Lighting Team within streets along with the guidance and help of Professors Carlos Gomez de Llarena, Huy Bui, and Katherine Morwaki.
Once the team was assembled and the equipment was ready the team began to create their lighting design plan and began the process of execution. Within this document you will find instructions on how the team created and installed a solar lighting system within the Parsons Street Space for the community to enjoy and hopefully for future classes to utilize as well.
Below is a list of all the items that we used to build this project.
Voltaic Solar Panels (6) - Voltaic donated 6 Solar Panels and 15 LED lights. The solar panels we utilized were We utilized 6 3.5 Watt Voltaic Solar panels. Purchase here
- Voltaic LED Touch Lights (15) - Voltaic donated 15 LED Lights which allowed us to create 5 sections of lights with 3 lights per section. Purchase here
Voltaic Battery Chargers (6) - We had five battery packs to power each lighting area and the sixth battery pack powers the Arduino. Purchase here
Voltaic Wire Male Splitters - We used these splitters to help with connecting the light sections Purchase here
Voltaic Wire Female Splitters - We used these splitters to help with connecting the multiple light sections Purchase here
Voltaic Female Adapter - This adapter is used to connect the battery pack to the solar panels. Purchase here
Arduino Uno (1) - Purchase here
Adafruit Latching Mini Relay Featherwing (5) - We utilized 5 latch relays. One for each light section of the street seats area. Purchase here
Adafruit TSL2561 Digital Luminosity/Lux/Light Sensor Breakout (1) - This sensor will determine and read the light in the environment. Purchase here
Adafruit RTC Timer (1) - This timer will help with waking up and putting the system to sleep. Purchase here
Wire - Purchase here
Copper Clad Aluminum Transparent Speaker Wire -
Wire Sleeve - We utilized Beige so it would blend in with the Bamboo. Purchase here
Heat Shrink Tubing - Purchase here
Solder & Soldering Iron
Pelican Weatherproof box - Purchase here
Step 1: Lighting Design Narrative
Lighting & Lighting Control Plan
The objective for lighting design was to integrate lighting within the structure. We wanted to make lighting be part of the project instead of just an addition. As Bamboo structure created grid where plants would hang, we thought that we should incorporate lighting within the plant pouches. In that way, we would illuminate the structure within the plant pouches, illuminate the plants, and also hide fixtures from noticeable eye sight.
We have decided to place fifteen LED lights inside the plant pouches. The lights would be placed more densely at the highest part of the structure and gradually sparse toward each end. The overall lighting layout is planned to create an interesting and playful dynamic at night inviting people to enjoy the seating.
As mentioned before, our main power source would be provided via solar energy, therefore we wanted to use the most energy efficient lighting fixtures - LED. The lights would be powered by batteries, which would be daily charged by solar power via solar panels integrated within the structure.
One of the most important components of the lighting installation is to have control system that will turn light on and off at the right time. We have decided to create a smart lighting system by utilizing Arduino, a programmable micro controller. By programming the Arduino, the lights would turn on at dusk, at the same time as urban street lights. The lights will be on until the Arduino turns them off after four hours. Once the Arduino turns off the lights, it will hibernate until the following sunset to preserve energy.
Step 2: Site Location & Environmental Conditions
Solar Panels Positioning: Sun Path Diagrams
- DSLR Camera/Phone Camera
- Fish eye lens
- Sun Path Diagram
- Light Meter (device that measure luminosity at a particular point)
Before we dived into designing the lighting, we needed to survey the site conditions, more specifically, we needed to know how much power we will be able to harvest daily. We needed to calculate the average direct sun exposure at the site with a consideration of surrounding buildings. One way to calculate it, would be to use computer software, such as SketchUp or Rhino, however, to do that we would need to model entire site including all surrounding buildings, nearby structures, and vegetation. After creating a model, we would have to use “shadow study” command to determine approximately how much direct sun exposure is on the site during the year. Instead, we used much quicker method - we calculated direct solar exposure by using a fisheye lens image of the site and overlayed a sun path diagram of New York City.
We took DSLR camera and fisheye lens and went to the site. We placed the camera facing towards the sky and rotated the camera so the top of the image would point geographical north. In addition, we tried to take picture at the same height the solar panels would be mounted to get the most accurate reading. After taking the picture, we needed to overlay a sun path diagram over the image. We used the NYC’ sun path diagram with coordinates 40.7128° N, 74.0059° W (the information can be found on https://www.sunearthtools.com/dp/tools/pos_sun.php). In Photoshop, we overlaid our fisheye image with the sun path diagram and started analyzing results.
From the diagram, we read that on June 21st we would get approximately 7h of direct sun exposure, while on October 21 we would get about 2h of direct sunlight (we used end of the October as lowest point since the structure would be disassembled by end of October). The difference between summer months and late fall months varied, however, we needed to adjust all of our calculations for the “worst case scenario." We found that are worst case scenario during month of October.
Secondly, we noticed that if we mount solar panels at the highest possible location, the surroundings would not obstruct solar panel performance therefore we decided solar panels would be mounted where the structure is highest and above 6ft from the ground.
Step 3: Battery Capacity
From solar study above, we determined to calculate our power consumption for the worst case scenario - which is only 2h of direct sunlight per day (see section about sun path diagram for explanation). In addition to that, we can’t assume that we will have sunny days all the time. In other words, we need to take into the account that our battery capacity needs to be able to support our lighting system for 2 or 3 days. That means that our batteries should be 2-3 times more than our load (LED lights) and the solar panels should provide enough power from only one bright sunny day.
Note on battery specifications V44 (rated for 44W, however, including some losses caused by circuit, USB power regulations, wires, etc. - 37W “true” capacity)
- Capacity: 12,000mAh, 44 Watt Hours
- Output: 5V/2A and 5V/1A USB (2 outputs)
- Input: 5-6V, 2A
- Battery Type: Li-Polymer
- Protection: Short Circuit, Over Charge, Over Discharge, Over Current, Over Temperature
Light fixture specification
- Input: 5V
- CCT: 3700-5000K
- Light output: 114-132lm
- Three light outputs:
- High - 500mA, 2.5W
- Medium - 230mA 1.15W
- Low output - 80mA 0.4W
Step 4: Power Needed Calculation
From this chart, we read that if we use V44 battery, we will be able to run our lights almost three days on medium output with fully charged battery. It was decided that our fifteen (15) LED lights will be powered by five (5) V44 batteries.
Step 5: Power Received Calculation
Since energy was generated through solar panels, we needed to calculate how much energy can be produced and what size panels should we use. Similarly to “Wh Needed” formula, we needed to calculate how much power we will generate daily to charge our batteries. The calculation includes rating of panel (measured in Watts), number of panels, worst case scenario direct sunlight exposure, and loss factor of 60% (the loss factor takes into account variation of solar radiation during the day).
Solar Power Specification
- Open Circuit Voltage: 7.0V
- Peak Voltage: 6.0V
- Peak Current: 615 mA
- Peak Power: 3.69 Watts
- Open Circuit Voltage: 7.0V
- Peak Voltage: 6.0V
- Peak Current: 1025 mA
- Peak Power: 6.15 Watts
- Open Circuit Voltage: 7.0V
- Peak Voltage: 6.0V
- Peak Current: 1500 mA
- Peak Power: 9.0 Watts
From the chart, we concluded that using two (2) 3.5W solar panels will be enough to fully charge batteries. When we run fifteen (15) lights for at least 4 hours per day for three days, with ten (10) solar panels, we will generate enough power to sustain our little energy cycle. Now that we calculations and the equipment details, we can move forward with designing the Arduino controlling system.
Total lighting and energy equipment list:
- 15 LED Touchlights
- 6 V44 batteries
- 12 3.5W solar panels
- Female/Male connectors
- Extension wires
All lighting and energy equipment was donated by Voltaic System. They helped us with calculations and energy system design and calculations
Step 6: Prototypes & Beginning Code
Before creating any code, it’s best first to discuss with your team what you’re trying to accomplish in the simplest of terms. This can also be consider, Pseudocode. Pseudocode is often used when first thinking through the process and functionality of code. An example to practice before you begin is thinking through how you would program a robot to walk. If you had a robot laying on a table, similar to Frankenstein, what would be the first thing you would tell the robot in order for it to stand up and start walking? Would you tell the Robot to sit up? Raise a leg? Or will the robot need one arm to support itself? If you were to use it's arm, do you need to tell the shoulder to lift it's arm up first?
When you start walking through each step you begin outlining every action the code will need to accomplish. There may be steps that the team may have overlooked. It’s better to catch these items at the beginning before getting too far into programming. The more clear you can be with your code objectives, the easier and more fun it will be to make it come to life. Below is an example of how the pseudocode would look for the robot.
Robot Walking Code //Open eyes //Open palms //Raise right shoulder //Bend right elbow
Beginning Code & Prototype
Below was the psuedocode that Jeana outlined based upon the team’s discussion on how the lighting system would function.
//Install Arduino into the Seat Streets area
//Plug in the battery packs to power the Arduino and each latch relay.
//Every ten minutes the Arduino will run a ten minute alarm.
//Once the alarm is called a light reading will occur.
//The light reading will determine an average amount and check if the environment is below 10 lux.
//If the light reading is above 10 lux, the Arduino will take a break and go to sleep for 10 more minutes and wait for the alarm to go off again.
//If the light reading reads below 10 lux and is therefore dark enough, the Arduino will trigger the lights to turn on.
//At this point the lights will run a short opening twinkle and remain on for the evening.
//The 10-minute alarm will continue as the night goes on checking to ensure the environment is dark enough for illumination.
//Next we will create a counter called NightCounter.
//The NightCounter will count and tally each time the 10-minute light check occurs once the lights are on. We’re going to use this almost as a third alarm.
//Once the NightCounter reaches so many counts, the lights will be told to turn off. Since we determined the lights will go off after three hours, and the NightCounter add one tally every ten minutes, we determined that the NightCounter max would be 18 (one Nightcount every 10 minutes equals 6 per hour, after three hours the Nightcount would equal 18).
//Once the NightTime counter reaches 18 counts the LED Lights will turn off
//The daily wake up alarm will be set for the following day of 3PM
//The Arduino will go to sleep
In our most simplest form our goal was for the lights to turn on and off when it became night. To achieve this we began experimenting with a photocell sensor. A photocell is a small inexpensive sensor that can read light from it’s surrounding area. By researching tutorials, we created a simple prototype that would react the way we were aiming for. When the photocell reads low light and sends this information to the Arduino, the Arduino is programmed to illuminate the LED. You can watch the video of this prototype being created and also watch the tutorial that Jeana replicated from.
The tutorial below is the example that the prototype above was created from.
The next step was to see if it was possible to connect one of our LED Voltaic lights to the prototype instead of the small LED light used in the tutorial. In addition to connecting one of the Voltaic LED lights, we also tested if the Arduino could run from the Voltaic battery. Below you will see how we used the same code as above, but rewired the Voltaic LED light in place of the simple LED light. Next we connected the positive and negative from the Voltaic light to the same inputs on the breadboard where the original LED positive and negative were located. Within a few tries we had a small functioning light system that resembled what we were aiming to achieve. You can watch the video below.
Once we were able to incorporate one light, we started experimenting with how the light might look within a plant that was discussed in our lighting design plan. At the end of this work week we had a functional prototype that we could show the team. From here we began to scale this prototype in order for it to illuminate 15 LED lights on a nightly basis.
Step 7: Scaling & Sensors
For our final lighting system we choose to utilize a more efficient light sensor, real time clock (RTC) and latch relays to control each lighting section. A latch relay can also be explained as a switch. When the latch opens it allows for current to flow through. When the latch closes, the current will stop. This functionality would help with conserving our batteries and give the overall system a longer lifespan. Below is a video of the lighting team experimenting with relays and creating our first scalable prototype.
In addition to using this new type of Luminosity Sensor, we were also needing to incorporate the RTC so that the system could properly turn on and off. The RTC is capable of being programmed to run two alarms. The first alarm we programmed will run daily at 3PM to wake up the Arduino. Once the Arduino is awake, the second alarm goes off every ten minutes to read the daylighting conditions at the site. After the lights complete their nightly cycle, the alarms would be reset.
Below are the two sensors and the latch relay we used.
- Adafruit Latching Mini Relay Featherwing (5) - We utilized 5 latch relays. One for each light section of the street seats area. Purchase here
- Adafruit TSL2561 Digital Luminosity/Lux/Light Sensor Breakout (1) - This sensor will determine and read the light in the environment. Purchase here
- Adafruit RTC Timer (1) - This timer will help with waking up and putting the system to sleep. Purchase here
Experimenting with Relays
In this video below you’ll see how the Arduino is programmed to turn on the light once the Luminosity Sensor reads below an average of 140 lux. However, once the counter reaches six counts, the lights turn off. This is once again a small scale prototype of how our larger system will function. However, instead of six counts, the lighting system on site would turn the lights off after 18 counts. There will be ten minutes in between each count therefore creating 6 counts per hour. This code can be found here
Step 8: Arduino Assembling & Final Code
- RTC Assembly - The Adafruit webpage that shows how to properly solder and wiring the connections to the Arduino.
- Luminosity/Lux Assembly - The Adafruit webpage that shows how to properly solder and wiring the connections to the Arduino.
Latch Relay Assembling directions
Feel free to also visit the learning section of the Adafruit website to also see how the team follwed along and wired everything properly. You can view the Latch Relay information here
- First we connected the battery wires to the battery pack and then opened them up to separate the ground and positive.
- Next we opened the LED Light wires to separate the ground and positive.
- Placed the positive wire from the LED Light into the Common input of the latch relay.
- Placed two positive wires within the Normally Closed input of the latch relay. One of these wires will be from the positive battery pack and the other will connect to the 3V input on the latch relay board to provide it with power.
- Next we soldered wire to the ground of the latch relay and connected this wire to the remaining ground wires from the LED light and the battery. At this point all ground wires from the battery pack, LED light, and latch relay will be soldered together.
- The positive wires from the 3V power input from the latch relay, the battery pack are soldered together and wired into the Normally Closed output of the latch relay.
- The positive wire from the LED Light is placed into the Common input of the latch relay.
- Finally, we added wiring to the Set and Unset switches on the latch relay them so they could properly connect to the Arduino pins. The Unset and Set will work as the one and off element of the relay board telling the relay when to open electricity (unset and ow electricity through) and when to cut off electricity (set and block current from owing).
- This was repeated 4 more times to accomplish 5 lighting areas.
- In addition to this lighting scheme the battery will be connected to two solar panels to receive daily charge. Within the next step is an illustration of how the entire system will work together.
Below is also a video of Jeana assembling a Latch Relay
Once your latch relays and sensors are assembled, you can download the final code from GitHub
Step 9: Diagram
Step 10: Virtual Reality 360 Film of Installation
You can watch how this 360 film in virtual reality with a VR headset or from your desktop. Use your keyboard arrows or mouse to move around the film to learn more about the project and also see how the space was installed.
Step 11: Final Product
Step 12: Thank You & Documentation
The team would like to thank all of those involved who dedicated their time and guidance with creating this space.
- Voltaic Systems
- Parsons School of Constructed Environments
- Parsons School of Design & Technology
- The New School Making Center
- Professor, Katherine Morwaki, Design & Technology
- The students and staff of the Spring 2017 Design Build Street Seats Team
If you have any questions about this Instructable please email Jeana or Gabi at their emails below. Also if you're in the NYC area, feel free to stop by and visit the space yourself. It will be installed until November of 2017. If you'd like more information about the space and it's location feel free to visit the website here at https://parsonsstreetseats.squarespace.com/
Gabi's Email: firstname.lastname@example.org
Jeana's Email: email@example.com