Inverters play a crucial role in any solar energy system and are often considered to be the brains of a project, whether it’s a 2-kW residential system or a 5-MW utility power plant. An inverter’s basic function is to “invert” the direct current (DC) output into alternating current (AC). AC is the standard used by all commercial appliances, which is why many view inverters as the “gateway” between the photovoltaic (PV) system and the energy off-taker.
Inverter technologies have advanced significantly, such that in addition to converting DC to AC, they provide a number of other capabilities and services to ensure that the inverter can operate at an optimal performance level, such as data monitoring, advanced utility controls, applications and system design engineering. Inverter manufacturers also provide post-installation services that are integral to maintaining energy production and a high level of performance for the project, including preventative maintenance, O&M services and a quick mean time to repair (MTTR).
As the price of modules fall, inverters and additional system components have become a focus in price reduction for EPCs looking for a new competitive edge. As a result, inverter manufacturers are continually trying to drive down the cost curve of products.
Some companies have been able to do that successfully with modifications to manufacturing strategies and building additional manufacturing facilities within emerging solar markets. Additionally, companies have taken the core concept of “design for manufacturability”—meaning they design a product with ease of manufacturing in mind—to design inverter products that are quicker and cheaper to produce, without sacrificing performance. Inverter manufacturers have also been able to achieve lower-cost success through well-maintained partnerships with vendors.
The continued challenge of providing higher and higher value at lower cost is something the industry must work to overcome.
Grid integration and inverters
High PV penetration and the impact it will have on our aging electric grid is another challenge the entire solar industry faces. The challenge itself isn’t specific to inverters, but the solution may be entirely inverter-driven. Because inverters serve as a gateway to the system, advanced utility controls, such as low-voltage ride through, can help mitigate the issues that stem from higher PV penetration on the grid, such as predictability of output and distributed generation. These functions help ease the transition as more solar is built, without the need for major and expensive infrastructure upgrades. Utilities are keen to support the development and use of inverters with the most proven functionalities when it comes to grid interconnection.
Given the growth in distributed generation projects along with continued development of utility-scale projects, solar project developers are seeking inverter manufacturers that can provide a robust suite of commercial products and technology topologies. A flexible inverter manufacturer can offer a centralized and decentralized inverter design, referring to an architecture that uses multiple inverters throughout a project to achieve the lowest levelized cost of energy (LCOE) possible. Although there’s still growing demand for a common system architecture using a centralized inverter, designing in three-phase string inverters for a decentralized PV system design is gaining in popularity. This is particularly true in commercial applications where space is at a premium or in an odd form.
Inverters have evolved from much more than simply inverting the electrical currents of a solar energy system. Inverters must continue to innovate and bring down cost, while maintaining key attributes for a solar energy system (reliability, efficiency and features such as data monitoring), in order to drive more PV penetration.