Solar Setup
When it comes to choosing the correct panels specifically for your van or mobile installations, there are three main things to consider. When it comes to solar panels, obviously we want them to be as efficient as possible. However, sometimes the most efficient panels are also the bulkiest and hardest to install. Before we really begin breaking down what is best for your needs, let’s first take a look at a few different kinds of solar panels. We will be comparing three types of solar panels: traditional rigid panels, semi-flexible panels, and semi-rigid walkable solar panels. We have personally used and experienced each of these 3 types of solar panels, and our favorite ones might surprise you!
Rigid solar panels, also known as traditional or crystalline solar panels, are typically made of crystalline silicon cells. These panels are known for their durability and efficiency. They are typically made with a glass top and aluminum frame and are the bulkiest panels we will discuss. Here are some key points to consider when choosing rigid panels:
1. Construction and Durability:
Rigid panels are constructed with a solid frame, usually made of aluminum, which provides structural support and protection for the solar cells.
The solid construction makes them more durable and less susceptible to damage from external factors like hail or debris.
2. Efficiency:
Rigid panels generally have higher efficiency rates compared to their flexible counterparts, meaning they can convert more sunlight into electricity.
This makes them suitable for installations where space is not a constraint, such as on rooftops or open fields.
3. Installation:
Rigid panels are commonly used in traditional solar installations, where they are mounted on fixed structures or tracking systems.
The installation process for a van build or mobile application can be much more difficult since you need to ensure that the heavy panel is properly secured. The best way to do so is through a roof rack, which can quickly get quite expensive.
4. Weight and size:
Rigid panels tend to be heavier and bulkier than flexible alternatives, which can impact transportation costs and the load-bearing capacity of structures.
Semi-flexible solar panels, on the other hand, are designed to be more adaptable to various surfaces. They can be mounted almost completely flat, which can reduce drag and make installation on a vehicle roof very easy. However, they also have some drawbacks, so here are some key points to consider with semi-flexible solar panels:
1. Flexibility:
Semi-flexible panels are made with thin-film solar cells, allowing them to bend to some extent. This makes them suitable for curved surfaces or installations where flexibility is essential. For a curved van roof such as a Sprinter, Transit, or Promaster, this offers the unique ability to add next to no additional height when installing your solar panels.
The downside is that the more the panels are bent, the faster they will degrade over time. Therefore, installation may require more attention to ensure the panels are not subject to excessive bending that could impact performance.
2. Weight:
Compared to rigid panels, semi-flexible panels are significantly lighter, making them more suitable for vehicle applications where weight is a critical factor. It may come as a surprise, but there are actually roof capacity ratings along with general weight ratings for every van on the market!
3. Durability:
While semi-flexible panels are designed to withstand bending, they may be more prone to wear and tear over time compared to rigid panels, especially in harsh conditions.
4. Efficiency:
While flexible panels can have a lot of benefits, one of the most significant downsides is that they are usually not nearly as efficient as rigid solar panels. In fact, after only 3 months on the road in ideal conditions, we were averaging about 45–55% capacity on our flexible
Last but certainly not least are walkable, semi-rigid solar panels. These are the panels we used on our last few builds (including our own van) and are our absolute favorite solution for multi-purpose, easy-to-install solar. Here are some things to consider with semi-rigid panels:
1. Flexibility/Size:
Semi-rigid panels are flexible but will not bend nearly as much as semi-flexible panels. These will easily fit the contour of a van roof, but any angle more dramatic than a few degrees would not work with these panels.
They are 1/4 inch thick due to an aluminum backing panel. This also makes them slightly heavier than the flexible panels, but still significantly lighter and easier to handle than a rigid solar panel. Since they are so thin, the profile from the side is also incredibly minimal. This keeps our van much stealthier than a rigid panel would.
These panels are also completely walkable, which is amazing. Rather than 400 watts and a roof deck, we were able to install 600 watts of solar and have a much larger deck since we can walk, sit, or dance on these panels. It is one of our favorite things about our van.
2. Efficiency
Compared to rigid panels and semi-flexible panels, semi-rigid solar panels are quite effective in ideal conditions. While they might not be completely comparable to a rigid panel, we regularly see 550W+ on our 600W array with these flexible panels. I would say they land somewhere between the two other options when it comes to efficacy but certainly end up closer to rigid panels than semi-flexible panels.
3. Installation
Perhaps one of our favorite features of these panels is the ease of installation. You can purchase a C channel and literally just VHB tape it to the van roof. There are no screws, no hardware, and no difficult roof rack to install when putting these panels on a van roof. They are easily replaceable as well!
4. Durability
One of the other benefits of semi-rigid panels over semi-flexible panels is their durability. These panels are incredibly robust, and even though only more time will be the true test of their durability, so far in the 6 months we have had them installed, we have noticed no decrease in efficiency or any cracking or premature aging.
4. Price
Sound too good to be true? This is where you find out what it is. These panels are the most expensive by far. When we were planning our build, we were a bit skeptical about spending so much on the solar panels. However, after adding the cost of a 400-watt rigid panel, a roof rack, decking materials, etc., we found that we actually saved about $900 USD by installing these panels. Not only that, we have more deck space and more solar capacity by taking this route.
After choosing the panels you want, the next consideration may be how to wire them if you have multiple panels in your array. There are actually three ways to wire multiple solar panels together. Parallel, series, and series parallel.
Parallel basically consists of a branch connecting the positive sides into one line and the negatives into another. It is probably the most straightforward and may be what you have seen others do on their builds. That doesn’t necessarily mean it is the best setup, though. The main downside of this is that, depending on the capacity of the panels, the amperage will increase incrementally as you add another panel. This means you will need to adjust your wiring accordingly to maintain the proper ampacity.
An example of parallel wiring
Series wiring, on the other hand, incrementally increases voltage over amperage, so you get the same amount of power but don’t have as many amps running through the solar wiring. Series wiring is accomplished by connecting the positive of one panel to the negative of another, essentially creating one large panel with a single negative and single positive on each side of the solar array. The downside of series wiring is that because you are essentially creating one large panel, if any part of one of your panels is shaded, it affects the entire array, resulting in a significant drop in efficiency. You will also need a MPPT-compatible charge controller with this method, depending on how many panels you have in the series.
An example of series wiring
The final type of solar wiring is called series parallel and is typically used for larger solar arrays, so you don’t often see it on van roofs since there isn’t a lot of space for panels. This type of wiring requires an even number of panels and is accomplished by connecting the positives and negatives of half the panels in series, then branching both series together in parallel. With this system, both age and amperage are increased; however, you will only have shading power loss across half of the system if one solar panel gets shaded.
An example of series-parallel wiring
Hopefully this is helpful, and you can see just how much these styles of wiring can affect the amount of wiring used in a specific setup. When it comes to electrical installations, wiring is often one of the most overlooked yet expensive elements. Simply choosing to wire your solar panels in a different configuration could end up saving you a lot of money!
Concluding thoughts…
If it isn’t obvious what our favorite solar solution is after 12 different setups, the Semi-Ridgid panels take the win for us! That being said, each of these panels has different pros and cons, and while these were our choices for our van, depending on your application and budget, the other options still hold up. If we had to rank them, we’d probably say: 1. semi-rigid; 2. rigid. 3. Semi-flexible.
Honestly, our recommendation would be to stay away from the semi-flexible panels all together. While they are cheap and seem appealing for all the different mounting applications, we found they never really worked that efficiently and quickly degraded since they are made of plastic and cheaper solar cells. The best application for semi-flexible panels is an additional array that can be hung up or plugged in but that is not permanently mounted to your vehicle.
For mounting panels, we would highly recommend that you do not drill holes directly into the roof since it will inevitably become a failure point where water and debris can enter the vehicle. Instead, use a roof rack, VHB tape, or we have even heard of some applications that use extremely strong magnets to attach solar panels (we have never tested this ourselves). This is again one of our reasons for choosing the semi-rigid panels, since the installation is fairly minimal and requires no drilling or compromising of the vehicle roof.
