TXC 171 Solar Hat Project - Final

Running head: CELLULAR CHARGING WITH SOLAR PANELED HAT 1

Cellular Charging with Solar Paneled Hat

Kayla Byers

Eunice Pae

Jason Chu

Shu Hua

UC Davis

CELLULAR CHARGING WITH SOLAR PANELED HAT 2

Cellular Charging with Solar Paneled Hat

While playing his favorite game, Hearthstone, Shu continuously ran into the same

problem – his cellular device would lose battery too quickly. He would usually be outside

waiting for classes to start, meaning he was too far from any wall for a traditional wall outlet to

work to recharge his phone. What he needed was a solution that was portable, yet able to give his

phone enough power to continue his game uninterrupted.

The garment that we create must solve the two main problems – lack of sun protection,

and charge his device without relying on external power. The wearable garment that was decided

upon was a hat because it is one of the main precautions used for UVB protection (Sun,

UV/Radiation/Electrical Lecture, 2016). Hats also provide a flat brim, allowing the

implementation of solar panels to be efficient and the execution effective. Solar panels would be

the ideal way to gain a charge for our garment’s device; the sun is in abundance in Shu’s area,

and it does not require him to be next to a wall outlet. By focusing on these two criteria, we can

solve Shu’s, and many other college students’, lack of power and lack of protection.

Conditions

Solar Panels

Our product took into consideration potential environmental consequences and

implemented solar panels into a wearable garment. This aims to not only reduce a smartphone’s

contribution in electricity consumption, but it also provides humans with the convenience of

readily charging their cell phones.

The solar panels will be constructed in a manner that follows the silhouette of the brim.

Lying underneath the solar panels will be a battery pack that stores the electricity converted from

the solar panel. There will be USB port on the battery pack that will allow consumers to access


this energy and charge their smartphones. To further enhance the element of convenience for the

consumer, the solar panels will be detachable from the brim. This allows consumers to wear the

hat as a normal clothing accessory, wash the hat, and more importantly, provide them with the

ease of replacing the solar panels rather than the entire hat.

Modern day solar panels can provide up to 10 watts of power per square foot ( Solar

Professional Services, LLC, 2016). Converted, that would be 0.07 watts per square inch. As

previously mentioned, we designed our hat brim to be 7.5 centimeters in length diameter. In

keeping with the golden ratio of 1:1.68 length to width, the brim width will be 12.6 centimeters

(Turner, 2016). In inches, the brim would be 2.95x4.96 inches, which is 14.63 square inches. Our

design calls for the battery to be held on the brim, allotting about 20% of the area which gives us

11.704 square inches of solar panel area. This means our hat design will provide about 0.82

watts.

The battery that we have chosen is a 9.4 watt hour rechargeable battery based off Goal

Zero’s Flip 10 Recharger (Goal Zero, 2016). To calculate we will take the battery capacity plus

40% accounting for efficiency loss and divide that by the current of power in watts (Khan, 2013).

Thus we have 9.4 watt hours * 1.4 which is equal 13.16 watt hours need for a full charge. 13.16

watt hours divided by 0.82 watts is roughly 16.04 hours for our solar panel hat to fully charge its

power bank.

Battery

In order to harness the solar energy acquired from the sun, it must be collected,

converted, and stashed into an energy storehouse. Specifically, the solar panel hat will

incorporate a rechargeable battery that will serve as a power bank when the hat is put to use. To


justify all technical specifications regarding charging power and battery capacity, our product

was modeled to fit the latest iPhone 6.

All base models of the iPhone 6 utilize a rechargeable lithium ion-powered (Li-ion)

battery in which houses approximately 1810mAh (milliamperes per hour). This holds a battery

capacity of 6.9Wh (watts per hour), which allows the mobile smart phone to sufficiently operate

on one full charge (Apple iPhone 6, 2016). To accommodate these features, our product will

incorporate a 9.4Wh rechargeable lithium-ion battery system with a cathode combination of

nickel-manganese-cobalt, which is loosely based off Goal Zero’s Flip 10 Recharger (Goal Zero,

2016). The capacity size of this battery consolidates approximately 3.6V and 2600mAh, and will

have hundreds of life cycles. Thus, this battery power source confirms more than adequate

charging efficiency. Moreover, Li-ion batteries have been accepted to charge faster, last longer,

and have a higher power density for more battery life in a lighter package (Apple iPhone 6,

2016).

Supplementary to its battery capacity, the Li-ion battery needs to be small enough to

aesthetically blend in with the hats silhouette. As mentioned previously, the rechargeable battery

pack will be situated below to the solar panels on the wide brim of the hat. Because of the brim’s

slim, extended, and leveled plane frame, the battery pack will resemble a similar shape as well.

Specific dimensions of the rechargeable battery have not been finalized yet; however, it will

feature a slender profile that will retain approximately 20% of the surface area. This positioning

will be most efficient in supplying a direct flow of energy: from the sun to the brim’s solar

panels to the Li-ion battery. Once a cycle has been complete, access to the battery’s stored

energy supply subsequently can be gained through a USB plugin port built within it.

Rechargeable batteries can efficiently reverse the chemical changes that occur during the


discharge process, which ultimately allows the battery to be restored to full charge and fit for

repeated usage (How do Rechargeable Batteries Work? , 2016)

Overcharging. A considerable concern regarding mobile charging through the use of a

rechargeable Li-ion battery is overcharging, which can prove to be destructive to any mobile

device. To address this primary issue, we have incorporated an automated self-timer within the

battery that will immediately shut off at the battery’s maximum capacity. A sound alert will go

off once 100% of battery capacity has been reached. There will also be a visible pale green light,

located on top of the brim towards the outer edge, shining through the woven polyester fabric

that will notify the wearer once a life cycle has been complete.

UV Protection

To provide adequate protection of the entire face, the hat will have a wide brim that is

greater than 7.5 centimeters in diameter. A wide brim will ensure that the nose and cheeks,

portions of the face that are negligibly protected, will be reasonably shielded from the sun (B.L.

Diffey, 2006). As for fabric, 100% woven polyester will be used to construct the hat throughout

because polyester is a fabric that exhibits high SPF value. This can be attributed to the existence

of benzene rings, a chemical structure of the polyester fiber that allows the fabric to effectively

absorb UV rays. Another important factor that affects the level of sun protection provided by a

fabric is color. Darker colored fabrics can offer more UV protection than lighter colors, because

they absorb more of the UV spectrum. Hence, our product will use dyed fabrics of medium to

dark shades as another precaution. To further enhance UV protection, titanium dioxide (TiO2)

will be spun into the polyester fiber as a delustering agent (Sun, UV/Radiation/Electrical

Lecture, 2016). This will not only reflect UV rays, but will also make fiber more opaque and

improve the overall appearance of the hat (Causin, 2015).


Comfort

Permeability. Comfort is the succeeding feature in the functional requirements for our

solar powered hat. Owing to the fact that the consumer will be consistently exposed to the sun,

moisture and heat are two conditions the body will be most subjected to. To maintain thermal

comfort, moisture vapor permeability and air permeability were taken into consideration.

Moisture from perspiration comes in two forms: insensible and liquid (Sun, Thermal/Heat

Protection, 2016). To combat liquid perspiration, a cloth headband will be lined inside the rim of

the cap. Cotton will be used for the cloth headband because cotton’s hydrophilic nature will

absorb the moisture from liquid perspiration, rather than repelling it. Furthermore, cotton’s high

porosity value allows the fabric to have a higher water saturation retention percentage. In other

words, cotton can absorb a significant amount of sweat by absorbing the liquid into the fiber and

holding it within the pores (Hsieh, Capillary Wicking, Absorbency, & Permeability Lecture,

2016). The absorbed liquid sweat can then transfer through the top of the hat through evaporative

heat transfer (Mihoces, 2007).

Insensible is a form of perspiration that is transported as vapor. To enable vapor to pass

through the air gaps between the yarns and fabrics, the fabric must be vapor permeable (Sun,

Thermal/Heat Protection, 2016). Permeability has a linear relationship with porosity; therefore,

when porosity increases, permeability also increases (Hsieh, Capillary Wicking, Absorbency, &

Permeability Lecture, 2016). As mentioned earlier, the hat will be composed of 100% woven

polyester. By manipulating how tightly or how loosely the fibers are woven, the porosity, and

therefore the permeability, of the hat can be adjusted. UV rays, however, were a variable that had

to be considered when determining the tightness of the weave. Taking into account that multiple

precautions will be implemented to the polyester fabric increase the UV protection, the weave of


the fabric can be looser in construction to ensure vapor permeability and breathability (Hsieh).

High porosity will not only provide air permeability, but will also deliver adequate thermal

insulation. The larger volume fraction of pore space allows more still air to be trapped within the

pores and provide insulation. However, high velocity winds can affect thermal insulation because

air will pass through the pores rather than being pocketed within them (Hsieh, Capillary

Wicking, Absorbency, & Permeability Lecture, 2016).

Methods

Our product is designed to be a piece of functional clothing. This means there are

requirements that need to be met in order to determine it as a successful and usable item. The

requirements can be looked at from three categories of clothing: Functionality, Environmental,

and Human.

Functionality. The first factor, functionality, asks whether or not our hat can accomplish

what is was designed to do. The purpose of the solar panel hat is to harness power from the sun

for recharging cellular phones and provide adequate sun protection for the wearer. We must then

consider three things: How much power can solar panels produce given the small area of a hat?

How long will it take to charge the power bank of the hat? Does the hat still offer an adequate

amount of sun protection?

To adequately test the functionality of this product, we will test the solar panel’s

performance with ASTM Standards E948-09 (Standard Test Method for Electrical Performance

of Photovoltaic Cells Using Reference Cells under Simulated Sunlight) (ASTM International,

2016). This will give us objective results demonstrating that our solar panels are performing as

expected.


Environment. The next factor that we must look at is how well the hat will react to the

environment. Our own field research of solar panels have discovered that many of them are fitted

with film, plastic, or glass to protect the panel from the environment. Additionally, many

manufacturers state that modern day solar panels are durable enough to handle severe weather

conditions (Brightstar Solar, 2010). It is, however, highly unlikely that our product will ever have

to meet with severe or even moderately disastrous weather as it is designed for casual and sunny

day wear. A simple film layer will be sufficient to protect it from rain and wind.

Human. The last factor to consider are human factors such as gender, age, physiological

size, and aesthetic preferences. To begin, we had set the shape of our hat brim to be that of the

golden ratio, which is most pleasing to people (Turner, 2016). The size is 7.5:12.6 centimeters, a

1:1.68 ratio. Additionally, we designed the hat to have a snap back in the back to allow for size

variations. This will allow the hat to accommodate as many head sizes as possible. The snap

back design will also have an opening which will allow for persons with longer hair to tie their

hair back if they should choose to.

While we have done all the theoretical values as to what should be comfortable, field

tests would provide us with solid evidence of our products wearablity. By giving samples of our

product to be worn by members of the target audience, then getting feedback either through

focus groups or questionnaires after a week of use, we can expect to either get confirmation that

our garment is comfortable to wear or that there are problems that were unseen and can be

addressed at that time.

Aesthetic preferences cannot be accounted for objectively. The color of our hat as well as

any design logos will be the result of subjective surveys and market research. While we expect to

have a darker colored fabric, perhaps the end user would find that giving a marginal amount of


UV protection for a greater aesthetic appeal to be valuable. We would ideally be able to gain that

knowledge through focus groups with our targeted user – college students like Shu. These would

provide us with subjective results, but the appeal to how a hat looks is very important as it is

often the focal point of an outfit design (Turner, 2016). Poor unity to other clothing or an

imbalanced design will result in the hat not being worn at all, which will keep it from charging

and protecting the end user.

Conclusions

We have plans for several tests to ensure that our garment works as expected, including

objective measures and subjective ones. While we hope that our garment performs as expected,

we are prepared to reevaluate any points that come up through our testing. Perhaps end users find

the brim heavy, or the transfer of the energy to the battery from the solar panels do not work as

efficiently as we calculated. This is why our tests focus on the functionality of the solar powered

battery, and the comfort of the hat while being worn.

A final condition that could possibly affect our garment, one that we have not yet

explored, is cost. Since our end user is college students, and many of them do not have large

amounts of disposable income, it would limit our consumer base if the price was unobtainable.

To figure out how much our garment would cost to the end user, we will need to look into costs

of manufacturing the solar panel and battery unit. The fabric and construction of the hat can be

manufactured in a separate factory, and hats are easily made in bulk. However, with the finishing

we desire for UV protection, this could add substantial costs.

Our hat will be able to solve both of Shu’s issues with an easy to wear garment. The solar

panels will charge the battery in 16 hours, and at the same time, provide the user with ample UV


protection and comfort. Once we are able to price out the garment and run our quality tests, we

will be able to provide users with an easy solution to their problems.


References

Solar Professional Services, LLC. (2016, March 11). Solar & Renewable Energy FAQs.

Retrieved from Solar Professional Services: http://solarproservices.com/index.php/faqs/

Apple iPhone 6. (2016, March 11). Retrieved from GSMArena :

http://www.gsmarena.com/apple_iphone_6-6378.php

ASTM International. (2016, March 11). Retrieved from Solar America Board for Codes and

Standards : http://solarabcs.org/codes-standards/ASTM/index.html

B.L. Diffey, J. C. (2006, July 29). Sun Protection with Hats. Retrieved from British Journal of

Dermatology: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-

2133.1992.tb14816.x/abstract;jsessionid=F677E4C2BFEDB7EFF007BF58D8A2B3D8.f

02t04

Brightstar Solar. (2010, August 4). The Strenght and Durability of Solar Panels. Retrieved from

Brightstar Solar: http://brightstarsolar.net/2010/08/strength-and-durability-of-solar-

panels/

Causin, V. (2015). Polymers on the crime scene: forensic analysis of polymeric trace evidence.

Springer.

Goal Zero. (2016, March 11). FLIP 10 RECHARGER. Retrieved from Goal Zero:

http://www.goalzero.com/p/307/Flip-10-Recharger

Heish, Y.-L. (2016, January 27). Wetting and Moisture Properties Lecture. UC Davis, Davis, CA.

How do Rechargeable Batteries Work? . (2016, March 11). Retrieved from Human Touch of

Chemistry : http://humantouchofchemistry.com/how-do-rechargeable-batteries-work.htm

Hsieh, Y.-L. (2016, January 25). Capillary Wicking, Absorbency, & Permeability Lecture. UC

Davis, Davis, CA.


Hsieh, Y.-L. (2016, January ). Functional Clothing Lecture. UC Davis, Davis, CA.

Khan, W. (2013, March 23). Easy Battery Charging Time and battery Charging Current Formula

for Batteries. ( with Example of 120Ah Battery). Retrieved from Electrical Technology:

http://www.electricaltechnology.org/2013/03/easy-charging-time-formula-for.html

Mihoces, G. (2007, February 20). Baseball caps to have new feel. Retrieved from USA Today:

http://usatoday30.usatoday.com/sports/baseball/2007-02-19-baseball-caps-focus_x.htm

Pierotti, L. (2016, January 30). How to Choose the Best Solar Charger. Retrieved from Outdoor

Gear Lab: http://www.outdoorgearlab.com/Solar-Charger-Reviews/Buying-Advice

Smirniotis, M. (2016, March 4). The Best Portable Solar Battery Charger. Retrieved from The

Wire Cutter: http://thewirecutter.com/reviews/best-portable-solar-battery-pack/#amps

Sources of Greenhouse Gas Emissions. (2016, March 11). Retrieved from US Envriomental

Protection Agency : https://www3.epa.gov/climatechange/ghgemissions/sources.html

Sun, G. (2016, February 17). Thermal/Heat Protection. UC Davis, Davis, CA.

Sun, G. (2016, February 22). UV/Radiation/Electrical Lecture. UC Davis, Davis, CA.

Turner, N. (2016, March). Basic Design Principles Lecture. UC Davis, Davis, CA.


Specification Sheet

STYLE

PURPOSE

FABRIC WOVEN POLY FINISHING TiO2 BATTERY 9.4WH LI-ION

FABRIC 2 COTTON BRIM 7.5cm POWER SOURCE SOLAR

SHU HAT DESIGN CO.

0001

RECHARGE CELLULAR DEVICES

Documents

TXC 171 Solar Hat Project - Final