Much like a new car, solar monitoring and control systems have options available to the owner and operator. And much like car options, some monitoring upgrades are important and relatively inexpensive, some are nice to have and other things really make the site a Rolls Royce system. It’s up to you (and the budget) as to which options make the best sense for each site. We’ll take a look at some important monitoring systems.
Inverters
The first monitoring point that jumps out is DC feeder currents and voltages. More inverters are equipped with current transformers (CTs) within the DC input section, which provides data to the inverter controller. The site data logger can then poll the controller and export the information to the web portal provider. This would be a great diagnostic tool to help pinpoint a combiner box that is off or if currents from each combiner box are low.
If the inverter cannot provide this function, another option for DC monitoring is to include the DC CTs within the DC disconnects adjacent to the inverters. Most, if not all, major manufacturers can include this option within their DC disconnect, so look to them for Plan B if necessary.
Combiner boxes
Combiner string DC current monitoring is an option as well. There are two schools of thought relating to that option: 1) That’s too much date to review; and 2) Give us all the data we can get. The middle ground I like to take is yes, give us the data, but not to review. Instead let’s mine for anomalies and trends. How much current each string produces is not relevant. How it compares to the string right beside it is more critical. Monitoring allows alerts to be issued that there is a problem on-site. The issue could be as simple as tall grass or as serious as a ground fault in the string itself, but at least you’re alerted to a problem.
Trackers
More and more sites are utilizing single-axis trackers on site and they have a wealth of data available, too. Array positioning angles are important to know, as if one tracker has not rotated in the last two hours, a service call is necessary.
Security
Site security and access is another point that can be included in a good monitoring system. Cameras with IR illuminators can watch the site 24/7 and be remotely monitored. There are radar-based sensors that can “see” much further than the human eye and be programmed to watch for any motion on-site. Having a strong outer perimeter and a reliable access control system is important, and with the right controls in place, it is possible to know who is on the site, when they arrived and left and what work was accomplished.
So think about how the power of the microprocessor can help you to install reliable monitoring systems to keep your solar fields safe, secure and running at their peak. When you look at the cost/benefit ratio over the long-term, I think you will find that including these enhanced reporting points adds value and profitability to each site and they are a good investment to make on several levels.
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