An extraordinary amount of research, design, technology, and innovation goes into the creation of every Goal Zero product, from the earliest CAD drawings to the final phases of production. In our From the Engineers series, we get a behind-the-scenes look at the development of our portable power, solar, and lighting products, straight from the engineers who design them.
We recently released our new Nomad 7 Plus Solar Panel, a panel that we feel is a big step up from our current product offering. We sat down with a few of our engineers to hear what they had to say about the panel, the design process, and the tech behind it.
Where we stand with solar
Keyvan Vasefi, VP of Engineering
When you think about a solar panel and how we capture energy, there are a few components. At the very basic level there’s the cell, which is this silicon wafer that’s about 5 inches wide and is designed to take light and turn it into electricity at its most basic level. So everyone in the solar industry is trying to do a lot of research and figure out what the next step we can take in terms of efficiency; if you have X amount of cells with light hitting the surface, how much power are you actually getting out of it versus what you should theoretically get out of it.
There are improvements being made by the industry and things have changed a lot in the last 15-20 years; however, recently it has been only small incremental improvements in efficiency. Some of these improvements take you from 20% to 25% efficiency but they can cost you five times as much. It’s important to find the balance between cost and efficiency, but in a lot of situations it is just better to have a little more surface area than to pay five times as much.
Much of our focus and innovation happens beyond the cell. We find the best cells that we can for our application, then a lot of the benefits you get from our work happens after you turn solar energy into electricity. That’s where we’ve done a lot of interesting work with our new generation of panels. We’re worked to answer the question; how do the electronics maximize the capacity of the solar cells. That’s where we’re at right now because the technologies out there seem to hit this wall of efficiency and cost, but we are always working on more efficient cells.
The new panel
Keyvan Vasefi, VP of Engineering
The easiest way to explain the new panel is to compare it to the previous version. When you think about the current Nomad panel on the market, it’s a fully integrated product. But I like to think of the Nomad 7 Plus Solar Panel as more of an ecosystem. We decided to break down the panel further to better optimize it for certain use cases. What we ended up with was instead of just one panel with everything on it, you now have three subsystems.
The first subsystem is just the panel itself that takes the photovoltaic energy (sunlight), captures it and turns it into electricity. We worked to make this subsystem the best that we could and took it from the 16 oz. on the V2 to now be 4 oz.
The second subsystem is the junction box. On the old panel it was built onto the back pouch, with the Nomad 7 Plus we decided to split that off and make it a modular component. Technology is constantly changing, especially with USB and mobile devices, so we wanted to create a way, if we need to, for people to upgrade without having to buy a whole new panel. The other thing we worked on was to build a level of optimization into the electronics.
Think of a solar panel as a car. The engine is designed to work at an optimal amount of horsepower at a certain RPM and if you didn’t have a multi-gear transmission, you would have a really hard time getting that car to both go up a hill at 10 mph or fly down the freeway at 70 mph. The only way to get that engine to work efficiently is to use that multi-gear transmission. There’s a technology in the solar industry called Maximum Power Point Tracking (MPPT) which is effectively an automatic transmission for a solar panel. The solar panel is designed for a certain peak and the MPPT controller effectively makes the panel feel like it is operating at peak performance even if there aren’t optimal atmospheric conditions. It basically allows us to use all available energy coming from the panel while minimizing waste. This technology hasn’t traditionally been put in portable panels, so we challenged ourselves to get some level of MPPT tech into our electronics and we now developed and patent-pending process to do just that in the Nomad 7 Plus.
The third subsystem is the kickstand and we worked to build a few different solutions into it. By nature, panels are trying to capture as much solar energy as they can so they heat up. Batteries don’t like heat so you can easily run into problems putting a battery right on the back of a solar panel or built-into one. We purposefully designed the kickstand to provide a buffer from the heat of the panel. It also allows users to set the panel out at a nice little angle without having to find something to lean it against.
The need to change
Sterling Robison, Electrical Engineer
Everything we did on the Nomad 7 Plus was to get around certain pain points we found with the older version. One of which was improving the charging experience for phones. What we did to address that was first, the dynamic auto-restart feature. There’s a few other products out there doing something similar, but they don’t directly solve the problem. We’ve actually got an algorithm in there that watches for your phone to say, “Hey, I’m not going to charge anymore. There’s something wrong here,” which usually happens as a result of a cloud or something interrupting the supply of power. Instead of waiting around for things to sort themselves out, this algorithm takes over, communicates with your phone and gets things moving again.
The other thing we did was the MPPT, where we have the ability to measure the available solar power coming from the solar panel and then, through another algorithm, we can match the available power with what your phone is asking for. We developed a way of helping your phone take less power by manipulating the level of power on the output of the USB.
We also wanted to help people use the panel more efficiently so we added the Solar Intensity Indicator. It’s not just a light that shows you the sun is out, it actually shows you how much power is available for use. Hopefully that fixes the situation where people aren’t positioning their panels correctly and takes the guesswork out of charging times from solar. Another thing I’m really excited about is being able to know not only how much power is available, but how much power is my device actually taking. What a lot of people don’t know is there are quite a few variables when it comes to how much power is going into their phones; like how long your cord is or how you even plugged in the device. We set up the indicator lights to communicate through blink rate on those same LEDs. We wanted people to be able to quickly recognize what is a fast or slow charge.
Basically you’ll put the Nomad 7 Plus in the sun and you’ll see some number of the LEDs light up. Roughly what that means is for a single LED you have about two watts of sun and when you have all four lit you have about five watts or more. So those will be solid lights. On top of that, to get the information about how fast your device is charging we’ve got a blink rate. We feel like we’ve nailed a frequency there that people just inherently understand. I think after people use it a few times they will quickly pick up what’s a good charge and what’s not.
The combination of all these developments will hopefully help people have a better experience when charging from solar.
Look and feel
Hank Howell, Industrial Designer
The Nomad 7 Plus was actually a very challenging design project because it’s a solar panel. There are so many solar panels out there now; it’s a flat 2D design project. So it was difficult to find a way to make it really jump forward and be innovative. We looked at a whole bunch of different ways of doing it; we tried to break out of the box of sewing and stitching. We didn’t want to do it the same old way. We stumbled on this technique that we’re using now which is a lamination process. We can make the panel super flat and thin which takes a lot of the weight out while also improving the durability, water resistance, and temperature regulation. So it’s pretty exciting to see it come together.
The main feature from and industrial design perspective is the leg which acts as a kickstand. It can hold the panel up at the right angle, it has a pocket built into it that you can put your rechargers or phone in, and if you don’t want to use it, you can just pop it off.
This design was really driven by the lamination process. We really had to get a good grasp on how this lamination process was going to work and then we had to work within those confines. What layer gets the graphic? Is it laid on top or is it laminated within? Things like that kept the project really interesting and it was a lot of fun to get into a different world of design. Also figuring out what we could do with the kickstand to not add weight or complexity but still make it really user-friendly and easy to understand. That whole process was a lot of fun and it did take some time.
The panel is lighter mainly because we were able to change the PCB that we stick the solar wafers to. It’s thinner, but it doesn’t sacrifice much strength and it’s a very rigid material. We got rid of all the extra fabric, stitching, zippers, cords, and junction boxes and really consolidated everything.
The Nomad 7 Plus is a lot more refined and simple. So it’s a lot smarter in every way.