|Keywords||, , , ,|
Campus Center for Appropriate Technology (CCAT)|
Humboldt State University Students
Engr305 Appropriate Technology
|Cost||USD $ 156.28|
|SDGs Sustainable Development Goals||
This project was implemented because CCAT had two 100 watt solar panels that served no purpose, but were already mounted on a wall in an optimal location for sunlight. Solar panels are designed to absorb the sun's light and convert it to electricity for our consumption. The solar kiosk is a charging station that has a "Dual USB Power Charger" that has its own volt regulator inside and a volt regulator to control the volts coming out from the panels at about 24V max and in to an inverter at 12 volts direct current (DC). The inverter is 200 watts which supports two 120V alternative current (AC) and has a USB port. There is also a 20 Amp fuse on the positive wire coming from the panels that will stop the flow of electricity if there is too high of a current flowing through. CCAT wanted a simple yet fun way for people to directly see where their energy is coming from. The system consists of no lead acid battery, so the system can only run if there is enough sun to generate enough current and voltage. With no battery, we are reducing our carbon impact as well as showing the educational purpose of the system to the full extent; it only works with sufficient sunlight. This demonstrates what it is like to use energy off the grid that is a renewable energy source which decreases your carbon footprint as well.
Background[edit | edit source]
At Humboldt State University in Arcata, California, the Campus Center for Appropriate Technology (CCAT) has a pair of photovoltaics solar panels that are currently not in use. They were originally from a past project called CCAT Solar Charging Station which was created as a solar charging station for students to charge electronics while outside. There is a battery, charge controller box, a USB converter, and fuse cords along with the solar panels, but are not in working condition and will need to be replaced in order for the solar panels to function properly. The panels are 100 watts each and in good condition. For the course, Engr305 Appropriate Technology this spring of 2017, students Ty M. and Tyler S. have been given the task to make use of the solar panels into a "Solar Kiosk" stand where students will be able to learn the potential of off-the-grid solar use as well as enjoy possible music box and phone charging capabilities. This will demonstrate the use of appropriate technology, turning something old into a new, updated more appropriate use of the solar panels for CCAT's needs. They would like to see a functioning solar kiosk come to life. The kiosk will be located near the CCAT papercrete clayslip demo wall in front of the house. The project will be implemented in the late spring semester of 2017.
Problem Statement & Criteria[edit | edit source]
The objective of this project is to reactivate CCAT's two functional solar panels so that they will provide renewable energy to the public and satisfy a small portion of the population energy demands. This project will look into finding the best application of power for the kiosk given possible limitations.
The following criteria will be used to address the Solar Kiosk's success. These criteria were chosen based on the recommendations of one of the CCAT directors as well as the students working on this project, Tyler S. and Ty M. The following criteria and constraints are ranked from 1-10, indicating how crucial they are to the project with 10 being the top priority.
|Reusable Material||Parts from the previous Solar Kiosk project may be used again as well as local used materials.|
|DC Appliances||Only certain electronic devices under a specific amount of wattage may be used.|
|Functionality||Transfers solar energy into usable electricity.|
|Energy Usage||Try to not buy new materials or else it defeats the purpose of self sustaining energy.|
|Accessibility||Available/easy access to the public for charging an electronic device.|
|Educational||Informs the public about the potential of solar energy and demonstrates an example system.|
|Cost||Must not exceed budget|
|Legibility, Readability, and Comprehension||Make sure the project is understandable for the general public.|
|Aesthetics||Professional and interesting to make people want to use it/check it out.|
Literature Review and References[edit | edit source]
Solar Panels Description[edit | edit source]
Solar panels transfer energy from the sun and convert that energy into electricity, a concept called photovoltaics. The general process behind the photovoltaic idea is first the sunlight strikes the solar panel, second the material on the solar panel (mostly silicon) absorbs the sunlight which forces the electrons to leave the silicon atoms and then flows on through a material away from the solar panels to conduct electricity.
There are two types of photovoltaic systems that solar panels use; first is the off-grid system and second is the grid-tied system. The off grid system is designed for rural types of environments and a major purpose of the off grid system is to provide electricity where there is not enough electricity on the grid. It stores power in the solar panels and then that energy can be used later (night time) when the solar panels are not generating electricity. The grid-tied system uses solar panels to collect energy and provide to the community on a big scale and provides lots of energy, for example a college campus. The grid-tied system is also connected to power lines, therefore if the solar panels did not work, the power lines would provide the electricity to the public. This system uses the solar panels to produce electricity first and as a backup system, the power lines will provide electricity if necessary.
Client Criteria[edit | edit source]
The client for the CCAT solar kiosk are students who live in the CCAT house, more specifically the three co-directors. It is important that we take in their considerations for how the kiosk should be built and function very precisely. Residents of CCAT know first hand what the people who will be using the kiosk most want, as well as the needs the kiosk should be addressing to assure the solar panels function are being used appropriately. Their criteria may change as the semester goes by, but as of now CCAT mainly wants the kiosk to be up and running again with new parts so the solar panels can work properly. Beyond that, they want the kiosk to be able to bring more thrill and excitement to their volunteer Fridays for students who come out to work with them. So far, they have mentioned they would like to see the kiosk be able to charge a speaker and phones so music can be playing outside along next to volunteers to keep them motivated and having fun working, yet showcasing a good example of appropriate technology. This would include making a storage box to keep the speaker and any adapters or chargers safe from theft and also safe from the weather.
Science Terms[edit | edit source]
Power is the rate of doing work or Power = Work/Time (Volts x Current=Power). Energy is the potential work that can be done on the system. It can transform into other forms i.e. solar into electricity, but energy can never be destroyed only transform. A Watt is the International unit for power and it is also a rate at which energy is being used or Watts = Joules/Time. A Joule is the international unit for energy and it is a Joule = Newton*Meter. Voltage is how much electrical potential an item has.
Solar Kiosk Components[edit | edit source]
Sizing[edit | edit source]
For our project we are given two 100 watt solar panels. One 100 watt solar panel could charge a 100 Ah battery in two days (20-25 hours), depending if the sun was out the entire day and the number of amps one 100 watt solar panel produces in an hour is roughly 5 amps. The number of amps depends on two factors; voltage and watts. To determine the voltage size on a battery, we need to know the number of watts a solar panel will produce and how many amps the total system produces. In a past solar kiosk project that was accomplished by CCAT, known as the CCAT Solar Charging Station, a few years ago. The number of amps being produced is 8.77amps and since we have the number of watts of a solar panel, which is 100 per solar panel. We can then find voltage on a battery with this formula, Volts = Watts/Amps. 100/8.77 = 12 Volts. So a 12 volt and 100 A/h battery may be required for our project.
A charge controller regulates how much voltage or electricity travels into the battery, preventing the battery from overcharging and overheating. The size the controller needs to be greater then the number of amps being used in our system. For example we have 8.77 amps and thus we would need a a charge controller great then 8.77 amps to protect the battery from not working properly.
Kiosk Material[edit | edit source]
The CCAT solar kiosk will be built on and around the already existing CCAT papercrete clayslip demo wall. The demo wall has an outer frame made of natural logs on the sides and 4x4 lumber running across the top to connect the two logs. The roof is made of 20 square feet of plywood layered with cedar shingles on top to act more roof like to protect the wall from rain. The inner wall is composted half by paper-crete bricks in the shape of cinder blocks and the other half is clay-slip-straw stuffed around the bricks. The paper-crete bricks are a mixture of paper:cement:water:sand at a ratio of 3:2:3:1. The clay-slip-straw is just straw dipped into clay. The straw remains in the wall by a wood lath allowing the wall to be maximally stuffed with straw with the bricks in the very center. Finally, the wood lath with the bricks and straw stacked in-between, is painted with a natural plaster.
Batteries, charge controllers, and fuses[edit | edit source]
Batteries can be necessary to be part of the system along with solar panels to store the energy made from the panels to provide a constant power source for charging equipment. Most batteries are used for storing solar energy and lead batteries can be recharged many time in their life.. Lead acid batteries recharge by having lead at the cathode end be oxidized and the anode lead is reduced. During usage, the cathode is reduced and the anode is oxidized. Lead acid batteries have the potential to last 10 years in optimal conditions. Although they realistically last around 5 years and are used heavily charging electronics, and weather is a factor in determining the life of a battery. Too hot of climates assist in degrading the battery.
Solar panels can haul in a lot of electricity, so a charge controller is needed to manage the flow of electricity in and out of the battery and cords running to direct current (DC) appliances. A charge controller makes it so while using the system to draw electricity out of or drawing in from the panels, the battery won't overcharge/overheat and brake. It does this by managing the flow of energy in and out from the battery; adjusting the current with a temperature sensor but still allowing the maximum flow of energy within the battery's capability.
It is possible a PV system could have a large power overload or grounding fault and could lead to damaged electrical equipment or even start a fire. Even in a small PV system, only charging DC appliances, it is necessary to use fuses for precaution. Fuses are a small piece of metal wire that melts when overheated which will stop the flow of electricity. Fuses must be replaced once melted. It is noted to buy fuses that can handle slightly more voltage than the normal current flowing through the system.
Direct Current Appliances[edit | edit source]
Temporary Direct Current, or DC, provides constant voltage or current in a single direction. For example a cell phone battery or any type of battery is a type of dc appliance. The battery provides the phone with power to function over a certain amount of time and when the battery runs out of energy, the phone does not function. Another analogy is a electronic portable device that does need to be fed constantly (like a wall outlet) is usually a dc appliance.
Some common examples of DC devices are bluetooth speakers, lighting, computers, cellphones, security systems. Rechargeable electronics such as computers, cellphones, and speakers use about 10-20 watts. Lighting use around 11-30 watts and security systems use 20-30 watts. For reference, a common household dryer uses about 2800 watts. The two solar panels should provide enough energy for small DC appliances.
Similar Examples[edit | edit source]
Jeanne Marie's story: Solar kiosk franchisee in Rwanda
Jeanne Marie Uhiriwe possess one of the 25 solar kiosks in Rwanda. The components of her kiosk consist of the following items; a pair of 40 watt solar panels, a lithium ion battery that draw power from the solar panels, 30 outlets to charge electronic devices, a big plastic container to keep the structure intact and a bike to make the solar kiosk easily transportable. People who want to use the device pay Jeanne 14 cents for two hours to charge any electronic device of the client's choosing.
One Billion Have No Access To Electricity — Solar Kiosks Can Help
SolarKiosk Gmbh is a company based out in Berlin that helps people in Africa to have better accessibility to electricity and one method they use to provide electricity to the public is by using the solar kiosk method. A standard solar kiosk that SolarKiosk Gmbh provides can charge 220 cellphones every day. Solar kioks also have the potential to charge items such as a laptop, a refrigerator and rarely a cell phone tower. The company has made accessible 45 solar kiosks to the public and one particular aspect that company is interested in is to observe the economic impact of many solar kiosks that are close together.
The Energy Kiosk Model, Current Challenges and Future Strategies
In a village called Avartsena, there were 5000 people with no access to electricity and then the Higher Education Research Institute opened up a solar kiosk in the village of Avaratsena in Madagascar in 2012. Which then people could rent lamps and use as a greater light source rather then using candles which are not as efficient and both of the items cost the same to use. Now people in Avaratsena do not need to walk several kilometers to charge their phone since they have a portable solar kiosk in their village.
Construction[edit | edit source]
Solar Kiosk[edit | edit source]
All of the wood that was used for the solar kiosk was use provided by CCAT.
1) Make a cube without the front on it with the following dimensions; Depth = 20 inches, Width = 17.25 inches and Height =23.25 inches.
2) Make a second cube without the front on it then place and screw on top of the first cube with the following dimensions; Depth = 20 inches, Width = 18.25 inches and Height 6 inches.
3) Create two doors (one for bottom cube and one for top cube) and attach hinges and locks for each door. The dimensions for the bottom door is; Depth = .5 inches, Width 16.25 inches and Height 22.25 inches. The dimensions for the top door is; Depth = .5 inches, Width 15.25 inches and Height 5 inches.
Look at image Solar Kiosk Prototype.
For staining purposes, we used Redwood Stain Latex which we bought at Ace Hardware. We used brushes and started staining with the grain of the wood. We applied two coats of stain.
Bench[edit | edit source]
The volume of the bench would take up is; Depth = 12 inches, Width = 30 inches and Height is 16 inches.
1) On top of the bench there are 4 boards that are 2 inches high and 6 inches wide with a depth of 15 inches.
2) The height of all the legs is roughly 14 inches, with a width and length of 2 by 4 inches.
3) The 4 reinforcing beams perpendicular to the legs are roughly 2 inches wide by 4 inches high with a depth of 6 inches.
4) The 2 reinforcing beams connected to the 4 reinforcing beams are roughly 2 inches high and 6 inches wide with a depth of 13
5) The final board adds reinforcement to where people sit on top of the bench with a width of 6 inches a height of 2 inches and a depth of 15 inches.
See the finished staining image for clarification.
Wiring[edit | edit source]
The wiring construction of this project went as followed:
1) Locate the positive and negative end of the cord coming out of the solar panels and locate the positive and negative wires coming out of the input on the volt regulator.
2) Wire a fuse in between the two positive terminals, one from the panels and one from the volt regulator.
3) After the two positive terminals are wired, connect the negative (Solar panel) terminal to the negative terminal of the Volt Regulator under where it says input.
4) Where is says output on the Volt Regulator, wire the positive (Volt Regulator) terminal to the positive (USB device) terminal and the negative (Volt Regulator) terminal to the negative (USB device) terminal.
5) Wire the positive (USB device) terminal to the positive (Inverter) terminal and the negative (USB device) terminal to the negative (Inverter) terminal.
6) Once your done wiring, test the inverter to make sure it works. If it works, solder the wires together in the same order as steps 1-5 describe.
Timeline[edit | edit source]
Proposed Timeline[edit | edit source]
|Objectives||Start date||Completion date|
|Collect Reusable Material|
|Purchase Project Components|
|Collect Testable DC Appliances|
|Implementation of Solar System|
|Create Interpretative Signage|
Actual Timeline[edit | edit source]
|Objectives||Start date||Completion date|
|Build Solar Kiosk Framework|
|Draw wiring schematic and receive CCAT's approval|
|Purchase Inverter, fuse and holder, and Volt Regulator|
|Implement Wiring System|
Cost[edit | edit source]
The following shows the materials used in our project as well as where they came from and price. CCAT has already donated two solar panels and wood, the rest of the technology will be bought from online or local stores. Material for the creation of the solar kiosk will be used and reclaimed material from various local shops and online.
|1||Sandpaper 4.5x11F 5PK and Sandpaper 4x4.5 CRS 60Grit||Ace Hardware||$8.12|
|1||In-Line Fush Holder AGC||Ace Hardware||$4.87|
|1||158PC Wire Connector ASST and AGC Glass Auto Fuse 60PC||Harbor Freight Tools||$12.99|
|3||Stain Latex Redwood Quart||Ace Hardware||$19.08|
|1||Screw WD PH CS6X1-5/8 and Hinge Narrow2-1/2 BB CD2||Ace Hardware||$13.00|
|2||Barrel Bolt 4 inches||Ace Hardware||$13.98|
|1||Pull Utility 6-1/2 inches and Sash Lift and Hinge Narrow 2||Ace Hardware||$16.57|
|2||100 Watt Solar Panels||CCAT||$0.00|
|1||200W/400W Power Inverter||Harbor Freight Tools||$21.69|
|1||24V Volt Regulator||Amazon||$19.98|
|34||All pieces of wood and screws were provided by CCAT||CCAT||$0.00|
|1||127 PC HS Tubing ASST W/CA and Soldering Iron Gun with Stan||Harbor Freight Tools||$9.00|
Operation[edit | edit source]
1) Arrive in front of CCAT and go towards the two solar panels on top of the CCAT papercrete clayslip demo wall 2) You will see a bench and kiosk charging station
3) Open the smallest cabinet on the top
4) Turn on the inverter
5) Plug in a three prong AC device or connect to the USB outlets
6)Turn OFF the inverter before you leave and close drawer
Note* It has to be sunny out in order for the solar kiosk to work
Maintenance, Schedule and Instruction[edit | edit source]
Maintenance[edit | edit source]
The following parts will be checked for this project:
- does the inverter turn on, a green light should appear, and charges a device
- check for water log inside the drawers of the kiosk. This may mean there is a leak somewhere
- make sure informative sign is visible/clean
- clean off the surface of solar panels
- check the bottom of the kiosk and the bench legs to see how it is holding up
Schedule[edit | edit source]
Every two weeks check:
- especially before it starts raining, make sure wires running down from panels to the kiosk are making a "U" shape in order to prevent water from dripping into the inverter
- if the inverter turns on and charges a device
- for water log inside the drawers of the kiosk
- to make sure informative sign is visible/clean
- clean off the surface of solar panels
- check the bottom of the kiosk and the bench legs to see how it is holding up
Conclusion, Discussion, Lessons learned, Next steps[edit | edit source]
Conclusion/Discussion[edit | edit source]
The solar panels that were provided to us by CCAT allow us to convert sunlight into electricity by using the following items; solar panels, fuse, volt regulator and an inverter. However not any AC appliance will function while plugged into the inverter, it has to be 200 watts or less when plugged into the inverter. Some devices that we used on our inverter were an iPhone charger and a laptop charging cord. With the right materials it is relatively simple to design your own solar system and you will be able to generate electricity in a very short time. NOTE: We have left two 20 Amp fuses taped to the top of the top drawer when needed.
Lessons Learned[edit | edit source]
Some lessons that I learned while creating this solar system include the following: 1) One can not be careless when designing an electric system. For example, if the output of a solar system is 24 volts, the inverter has to be under 24 volts in order for it to work. Or getting the right sized volt regulator, which should be higher than what the solar panels are outputting, to maintain a constant voltage that gets delivered to the inverter. Building the wooden bench and kiosk should be the least amount of our effort, even though it actually took longer to cut and build. Determining the size of a screw or a piece of a board does not matter in the end. In the end, making sure the electrical part is sized right is most important. 2) Weather can be difficult to work with when designing a solar power system, because the electrical system relies on the sun to produce energy, we cannot test to see if the system works unless the sun is out. Also, one can not build an electrical system while it is raining. 3) Everything will not go according to plan, so start working on a project earlier than later. In addition if there are problems, one can fix them and still be on track.
Next Steps[edit | edit source]
The most important next steps would be to get the wiring completely soldered. Right now the inverter is not soldered and only connected with alligator clips. This also makes the system open to theft so the inverter should be soldered on both sides of connection. Also, if after people start using the system and find they wish the USB dual charger port was more extendable, the wires will need to be replaced with wires for lamps or something of the sort. Also, maintenance check ups and using the system to know first hand if it's still charging. Other then that we will most likely not expand this project any further. Next steps could be to find what the biggest thing the panels could power, and do analysis testing on the system. Some other important things to do is make the inside of the top drawer, where all the equipment is, more waterproof. This can be done by putting pond liner around the inside of the top drawer. We have left some extra liner in the bottom cabinet. Also, the whole in the back of the box where the wires run into should be sealed up as well with a type of epoxy.
Testing Results[edit | edit source]
After Ty and I connected all the wires together on May 6 (see wiring section under construction) we turned on the inverter and were able to power the following devices with their appropriate cords. First was an iphone and second was an apple laptop. The wattage on both devices were under 200 and that number is the max amount of watts the system can produce. We found the efficiency of the panels to be 11.1% by using the formula =(Panel Power output)/((1000watt/m^2)(Area of panel)). We connected 200 watts to the inverter and covered one of the panels at 11 a.m. completely causing the inverter light to go red, which means the panels were not able to supply enough power to the inverter. We slowly uncovered the covered solar panel and at about half way uncovered, the inverter light turned green and supplied power once again.
Troubleshooting[edit | edit source]
|Sun not available||The availability of the sun depends on the weather thus we can not solve this problem.|
|Wire damage||The wire can be easily cut with the right equipment, therefore new wiring would need to be purchased.|
|Stolen Parts||To solve this problem we will screw in the following devices, first screw in a tupperware into the bottom on the top cabinet where the inverter sits in. If this is a major issue, the simple hinge lock on the drawer could be changed to have a lock on it that CCAT could lock at night. Second the solar panels are screwed into the clay slip wall structure. Third the solar kiosk is really heavy to lift so it would be difficult to steal, same as with the bench. And forth, the wires are screwed into the inverter, are fused with the volt regulator and fused with the wires coming from the solar panels.|
|Broken Parts||If the inverter, wires, volt regulator or the solar panels do not work. We would have to take it apart and use a multi-meter to determine where the voltage is not present.|
Update September 2018[edit | edit source]
The inverter for the solar kiosk has been stolen. The wooden frame of the kiosk is being repurposed to serve as a weighing station for the food production from the gardens. The kiosk allows for food data collection capabilities and has a garden map. The solar charging station will be functional again when a new inverter is put into place.
Team[edit | edit source]
Contact Info[edit | edit source]
Tyler Schroyer: Ths79@humboldt.edu User:ths79
Ty Muhovich: Tcm277@humboldt.edu User:TyMuho
References[edit | edit source]
- Nagawiecki, Tom. A Beginners Guide to On-Campus Solar Development, aashe.org/Google Scholar 2009 pg. 6-7.
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- Boxwell, Michael. Solar electricity handbook: a simple, practical guide to solar energy: how to design and install photovoltaic solar electric systems. Greenstream Publishing, 2012
- Sullivan, J. L., and Leigh Gaines. A review of battery life-cycle analysis: state of knowledge and critical needs. No. ANL/ESD/10-7. Argonne National Laboratory (ANL), 2010.
- Ruetschi, Paul. "Aging mechanisms and service life of lead–acid batteries." Journal of Power Sources 127.1 (2004): 33-44.
- Boxwell, Michael. Solar electricity handbook: a simple, practical guide to solar energy: how to design and install photovoltaic solar electric systems. Greenstream Publishing, 2012.
- Garg, Akshat. Charge Controller Solar Power Battery Charge System. Academia. RLH Industries, Inc., 2017.
- Khatib, Tamer. "Standalone Photovoltaic Power Systems." Journal of Applied Sciences 10.13 (2010): 1212-1228.
- Khatri, Ishan. What is the difference between AC and DC currents?. Quora Incrporated, 2015.
- Catalog of DC Appliances and Power Systems, Ernest Orlando Lawrence Berkeley National Laboratory, 2011. pg 26
- Gilks, Tom. Jeanne Marie's story: Solar kiosk franchisee in Rwanda, One Campaign, 2015.
- Richardson Jake. One Billion Have No Access To Electricity — Solar Kiosks Can Help, Solarlove, 2015.
- Knobloch, Claudia & Hartl, Judith. The Energy Kiosk Model, Current Challenges and Future Strategies. Endeva Business Model Library. 2014.