In May 2014, Judah Moseson with Infigen Energy provided insight into why a monitored solar system needs to include more than just energy production and dollars saved (http://www.solarpowerworldonline.com/2014/09/command-control-247-solar-monitoring-matters). As a follow-up to that article, I’d like to make the case for why much more than a revenue grade meter is required on all PV sites.
This article was authored by Keith Davis, Director of Solar Services at
Affinity Automation
As Moseson concluded, solar PV has indeed become a mainstream energy generation system. With the growth of large-scale systems across the country and the acceptance that solar is a clean and truly renewable resource, more and more savvy investors, landowners and EPC firms are supporting solar as never before. This indeed is a good thing.
But mainstream does not mean care-free. As solar generation continues to grow, command and control systems must continue to evolve. It is my belief that as solar energy production continues to increase at an exponential rate, the solar PV system command and control model will be required to match very closely the reliable protocols and standards that regulate and monitor large conventional electrical energy power generation systems. No one doubts a nuclear plant’s systems are far different and much more reliable and sophisticated in 2014 than they were even 25 years ago, so why isn’t control system evolution for PV just as important? I am confident the solar PV industry will soon adopt the same data reliability standards and high-performance requirements that the conventional generation industry has. It’s the next logical step in the evolution of solar energy production systems.
In some ways the solar PV industry is a victim of its own success. In the early years of solar, the connecting utilities could not foresee how much solar costs would decline, therefore increasing customer demand for solar energy systems. As such, early connection standards were somewhat simple and did not take into account the impact of a large amount of energy flowing “backward” on the grid. Nor was the impact of large energy fluctuations considered and the effect calculated on voltage and frequency regulation. But those days are past and solar is indeed making a huge impact on the grid and the utilities that take delivery of that energy and distribute it through their existing one-way infrastructure.
The manufacturers of balance of system (BOS) components take this challenge seriously. More and more inverters now can be regulated and controlled remotely to support the grid’s need for voltage and frequency regulation. Power factor adjustment is now becoming a necessity, and having the ability for the PV system to deliver apparent power and VARs adds more grid support functionality. Solar combiners now offer ground and arc fault detection and rapid shutdown features. All of these systems will require two-way redundant communications protocols that allow the utility to not only determine the amount of energy delivered, but also the ability to set and regulate the operational parameters to match real-world grid conditions. Systems could also respond quickly to a site emergency like a massive ground fault or fire, should one occur. I do not believe we, as an industry in 2015, are providing that level of in-depth capacity for system safety and control, but soon we must.
From a system operator’s viewpoint, command and control systems are excellent tools to determine how well (or how poorly) a system is performing so repairs and adjustments can be made quickly. The amount of system performance and operating data that will be accumulated will grow exponentially as well, and data mining software systems will be required to be in place to seek out performance anomalies in that vast data stream to alert the system operator there is a potential problem. The typical system in place today only looks at a few basic parameters and leaves the balance unmonitored, allowing a potential fault to occur, possibly shutting down the system or causing extensive damage that will cost time, effort and money to repair. No one wants that.
Today’s technology has the capability to perform these tasks and much more. In future articles, we’ll look at the points mentioned above in some detail, and we’ll discuss some of the performance parameters requiring monitoring and how control systems can maximize system performance and efficiency, increasing owner revenue and profits. Come join the conversation!
