Over the course of a shortened COVID-19 semester, I worked with a team of two other students to develop the design and prototype for a novel product. Our project? A new style of solar panel backpack built for the casual consumer. Our process included everything from market research to Gantt Charts. On this page, I intend to walk you through our entire design process.
"We had been operating under the pretense that our users would only want to use renewable energy to charge their devices. Unfortunately, this assumption alienates a sizeable potential market for those who are indifferent toward renewable energy. Including an additional way to charge our battery from grid power would provide our product with consistent access to energy and would our user base beyond renewable energy enthusiasts.”
The first phase of the design process is the ideation phase. For our team, ideation involved brainstorming multiple different product ideas and then choosing the best one. We came up with many ideas, from an electric toothbrush powered by electromagnetic induction to a design to prevent heel wear on slip-off shoes. Ultimately, we decided on our solar integrated backpack.
The design ideas and market research section are the results of my team’s first memo.
After deciding to develop a solar integrated backpack, my team conducted research on the portable electronics market and the mobile power banks market. We concluded that growth in portable electronics drives the demand for portable charging solutions and found that portable electronics would grow at an 8.87% compound annual rate. In addition to an 18.4% CAGR for portable power banks and technological improvements in solar, portable electronics market growth indicated that our solar backpack would find itself in a growing market. Next, we analyzed the solar backpack space.
Our team realized that most other designs were rugged, heavy, and intended for outdoor use when looking at other solar backpacks. There was one lightweight design intended for daily use, but it was aesthetically unpleasing and rigid. We decided that there was a gap in the market for casual everyday use and aesthetic appeal, so we focused our designs on that segment.
With our refined design goals in mind, we defined customer needs and developed new ideas. We came up with a solar mat roll idea, a solar integrated fabric idea, and an induction device idea. I generated the sketches you see below.
We quickly eliminated the induction device idea and moved forward with our fabric integrated solar panels idea. However, I would like to note that the solar panel roll design deserves a second look. The roll could feasibly be a large flap instead, improving ease of use and potential solar efficiency.
Our team was asked to further research patents and prior art for backpack charging systems and refine our designs for our second memo. We found seven patents, primarily for products in China geared toward rugged outdoor use. We continued research into other market products and found SUNNYBAG, a company seeking to use the same strategy as us. Today SUNNYBAG has a well-developed product line, and the company has grown significantly.
Next, we took our original three design ideas, in addition to the ubiquitous hard-shell design, and placed them in a weighted scoring matrix. From our matrix, we concluded that the integrated solar fabric was our best path forward.
It was at this point in the project that I brought a problem to my team’s attention. We had been operating under the pretense that our users would only want to use renewable energy to charge their devices. Unfortunately, this assumption alienates a sizeable potential market for those who are indifferent toward renewable energy. Including an additional way to charge our battery from grid power would provide our product with consistent access to energy and would our user base beyond renewable energy enthusiasts. Thus, the idea was integrated into our design.
By now, my team and I had a clear idea of the problem we were solving and the product we were making. “Electronic device consumers currently do not have a self-sustainable, lightweight energy source to charge their devices in portable luggage.” Our solution? To generate a fabric integrated solar charging system inside of a stylish backpack design. But what materials would we need to prototype this?
The first step to finding adequate prototyping materials is identifying our system’s subcomponents and energy inputs/outputs. These pieces of information help clarify the devices we need to aid in prototyping. Below is a diagram of our system inputs and outputs.
After identifying our system inputs, outputs, and subcomponents, our team began researching our potential prototyping materials. We found websites such as adafruit useful. We used our research to generate an estimated bill of materials which can be viewed below.
At this point in the semester, we also generated a Gantt Chart to schedule our prototyping. An integral part of our planning was assembling our system externally first. By not building directly into the backpack, we could test our system adequately before its integration.
Shortly after we submitted Memo#4, our team ordered our materials, and we began formal prototyping shortly thereafter.
I would argue that this is the most unpredictable and challenging part of the design process. Once we received our parts, we encountered many different issues. For instance, our 1.5V flexible solar panels from DFRobot did not have standard electrical connections. The positive and negative terminals were simply small metallic circles and required pre-heating to solder correctly. And then, upon initial testing, we realized we needed to order more solar panels.
Our final assembly contained ten wired as a series of 5 parallel pairs. This circuit delivered 10.29V and 0.51Aat optimal conditions and decreased to 9.47V with 0.67A after 3 hours. Thus, this system successfully delivered 1.0A to an iPhone for 5 hours and then a reduced0.67 A after that. The charging rate may have been slow after losing the initial battery charge, but we succeeded in making a self-sustaining system.
I enjoyed this entire process. It is stimulating to develop a novel prototype. If you would like to work with me, please fill out the contact form! Thanks for reading!
