Choosing the right solar system for your customer can feel like a daunting process, so to simplify the process, focus on the essentials. There are several basic components to consider in solar system design: the solar panels, the inverter, and the mounting and racking systems. Each of these comes with a range of options to choose from, but understanding the differences between them will ensure that you select the right system to meet your customer's energy needs.
There are a few different types of panels on the market the today, with the majority based on crystalline silicon technology. There are two basic types of silicon panels: monocrystalline (mono-Si) and polycristalline (poly-Si). Mono-si cells are highly efficient, and a higher power density, meaning you can get more watts out of a given area. They also tend to last longer, but their slightly higher price can be a downside. Poly-Si cells are less expensive to manufacture, and typically, dollar-for-dollar, you can get more power out of them. However, they have a lower efficiency rating, making them less space-efficient.
Other panels on the market, ranging from thin film to amorphous silicon, are less common and often less efficient, but can offer added benefits such as durability, lighter weight, flexibility, and lower price.
There are two main types of inverters available today, all of them much more efficient than inverters in the past (95-98% versus 80-85%).
String inverters are currently the most cost-effective inverter option available in the U.S. These inverters "string" panels together to create a single solar system--a reliable, easy-to-install technology. The downside of string inverters is that if there is any shading on any of the system's panels, the power output from the entire system would be reduced to the lowest panel production level, resulting in far less power generation. Another problem with these inverters is that all the power is aggregated so you can only monitor system output at the string level, so it is difficult to identify problems with a specific power.
Microinverters are more expensive per watt, but offer many benefits. Rather than one inverter being used for a string of panels, each panel has its own microinverter. This helps mitigate the negative impacts of shading issues, and allows you to monitor the performance of individual panels, making it easier to identify failure points.
The mounting system will have the biggest impact on the scope and challenges of an installation. Most solar systems rely on rooftop mounting, although this can present complications: roofs have their own set of concerns, from durability to drainage, that need to be considered when installing solar. Variables such as pitch can complicate the design and installation process, and those unknowns can add up quickly. Generally, a roof-mount system will have lower site costs, but higher labor and logistical costs.
Ground-mount PV systems are a great alternative, and can offer fast installation times while eliminating some of the obstacles of a roof installation. Sitework can be done in advance, the system is more easily accessible, and many of the logistical challenges of a roof installation are not in play. A ground-mount system requires a larger upfront investment, but the actual installation process is simple and efficient.
When it comes to a ground-mount system, you have three options to choose from: fixed-mount, single-axis trackers, and dual-axis trackers.
Fixed-mount systems set the panels at a fixed angle, meaning they are only maximizing production for a limited number of hours each day. These are an affordable, simple, and familiar solar solution, but they are much less efficient and will usually provide a lower ROI.
Single-axis trackers move the panels from East to West, tracking the sun as they go. They are much more efficient than fixed systems, and can generate up to 20% more energy.
Dual-axis trackers are a much more powerful version of single-axis trackers, able to move along both the x and y axes to maximize production throughout the day, as panels are always positioned at the optimal angle to the sun. These can generate up to 45% more energy. They are typically more expensive, and may require more land, but they provide the highest ROI.
When designing a solar system, carefully consider each component to ensure you're meeting your customer's energy needs. With a little research and a full understanding of your options, you'll be able to design a system that's efficient, reliable, and cost-effective--and that will make your customer feel good about going solar.