Summary: Keeping track of progress and problems at a large solar farm is a full time job. Software-based solar power plant monitoring systems facilitate continuous monitoring and reporting for these farms.

Why do we need monitoring for a renewable energy source like solar?

Some might argue that we don’t. We cannot anyway control a natural resource such as sunlight, so why bother to monitor, so goes their arguments.

There are enough reasons why we indeed need such a monitoring system. But before that, what is a monitoring system?

As the name suggests, a monitoring system continuously reviews the critical aspects of a product and reports on the progress of each component. Think of it as an automated, software version of a supervisor.

Solar power plants, especially large solar farms, today have sophisticated monitoring systems. These systems enable solar power plant operators to streamline operations and monitor the critical activities on a continuous basis.

Visualize the following situation: Imagine you are running a 10 MW solar power plant. A solar module typically has a capacity of about 250 W or 0.25 kW, and hence a 10 MW solar power plant will have 40,000 modules (0.25 kW x 4 gives 1 kW, and 1000 kW makes a MW).

40,000. Imagine for a moment 40 blooming thousand panels in front of you. That’s a large number of panels to keep track of, don’t’ you agree?

Manual monitoring for a large solar farm is almost impossible. We hence need automated monitoring solutions.

If a person were to spend just 1 minute inspecting each panel, it would take him an entire month to finish inspecting your solar farm, assuming the chap is a real superhuman who works tirelessly 24 hours a day, 7 days a week (and with no break for lunch!). More likely, it will take him 3-4 months to finish the complete inspection.

Software based solar farm monitoring systems provide you such a module level monitoring on a continuous basis. Imagine being able to spot a problem in 10 of the 40,000 modules within a few seconds of the problem’s origin. The human agent would have taken too long to notice it, if at all he does – he would have been busy inspecting the 39,450th module when the 175th module has a problem!

Some of the roles performed by the solar monitoring systems include

  • Detailed performance data down to the individual solar modules
  • Continuous comparison of actual system performance data against expected performance data.
  • Remote diagnosis and resolution of issues impacting system performance
  • Automatic emails and SMS of events affecting solar power plant performance
  • Performance reports 24/7 with access to backed-up online data storage.

Imagine what large savings a small investment in a monitoring system could provide.

A 10 MW solar power farm could generate up to 15 million units a year, and that could earn over $2 million in revenues (at about 15 cents a unit). A power plant without monitoring systems, owing to poor maintenance resulting from absence of monitoring, could have significant losses, and generate only 1.2 million units a year, equivalent of about $1.8 million in revenues. Now, an automated system is installed to the farm, that supervises the tens of thousands of solar panels 24 hours a day, 365 days a year. This will ensure that the same 10 MW solar power plant yields the expected 1.5 million units per year, yielding $2.25 million a year.

That is, the solar monitoring system has saved significant losses from the solar farm and delivered $450,000 (almost half a million dollars) extra year after year. The monitoring system for a 10 MW power plant typically costs less than $450,000. That is, the investment in the monitoring systems pays off within one year for this example!

Solar monitoring solutions cost a very small % of the total cost of a solar power plant, but they provide significantly large financial benefits.

If this is the benefit for a 10 MW power plant, imagine what it could be for a larger solar power plant owner, say a 100 MW power plant!
Questions from the curious cat

  • How much do these monitoring systems cost?

It is difficult to put a precise number for the price, owing to the variety of monitoring systems available in the market. They cost however a very small percentage of the total power plant cost, typically less than 1% of the total cost.

  • What about control and repair? Who does the repair and maintenance once a problem is reported by the monitoring system?

That depends on the problem being reported. There are some problems that could be remotely solved – for instance, if the solar panels’ output is much lower than expected on a particular day and this needs to be conveyed to the inverter manufacturer, the communication to the inverter maker could be carried out without any human intervention.

However, if a physical problem has been detected in a panel and it has to be replaced, usually human intervention is required to get it rectified. In this case, while the software will automatically notify the project manager about the panel malfunction, the actual replacement of the panel needs to be implemented as a manual action by the project manager or his colleagues.

  • Can I have reports from the monitoring system on my smartphone?

Absolutely. In addition to providing updates through web interfaces, monitoring systems today can send you updates and alerts to any kind of device – SMS to mobile phone, email to devices, notifications through smartphone apps, and more.

  • Do I need to purchase these monitoring systems from separate vendors, or do the panel or inverter vendors provide these as part of their offerings?

The solar industry today has monitoring system offerings from both pure-play monitoring system makers (whose only focus is to make high quality monitoring software and related hardware), and from inverter makers who typically bundle the monitoring system with the inverter.

Which of the two sources – pure-play monitoring system vendor or inverter manufacturer – is better depends on the specific requirements and constraints of the solar power plant owner.

  • How are monitoring systems different from SCADA systems (supervisory control and data acquisition) used in solar power plants?

SCADA systems typically are used to monitor large scale installations for power plants, and power distribution infrastructure such as the electricity grid. These systems collect data from various points in a system to provide intelligence on progress and problems. Some SCADA systems also include options that allow the supervisors or project managers to remotely control parts of the infrastructure.

SCADA systems are thus not different from monitoring systems. One could say that monitoring systems are a part of the SCADA systems.

  • Are there any serious limitations to these monitoring systems?

Frankly, there are very few reasons why you should not use monitoring systems. In fact, the monitoring systems to a large extent belong to the information technology/internet domains. As a result, most monitoring systems should be able to make use of the exciting technological advances in the computer, mobile and networking domains, and cost a negligible percentage of the total cost of the system. If we were you, we would not run a large solar power plant without advanced monitoring systems.

  • To what level do the monitoring systems provide intelligence? Can they even report if the panels have not collected as much sunlight as they are supposed to?

Monitoring systems today can provide intelligence and data at many levels – some monitoring systems can detect problems at individual panels level. Of course, the depth of intelligence depends on the monitoring system you select.

Some monitoring systems can indeed provide alerts if solar panels are not generating as much power as they should.

  • Where are these monitoring systems fixed?

Like any monitoring system collecting distributed data, solar power monitoring systems also collect data from various points in a solar PV farm. Depending on the depth of intelligence and monitoring you require, a solar monitoring system could be just one system that is provided at the inverter level, or it could further comprise small sensors and data collectors fixed to each panel, if panel level monitoring is required.

  • Do the monitoring systems work throughout the day and night?

Yes, monitoring systems are just a combination of hardware and software – a combination of sensors, communication networks and software. They don’t need food or sleep, they can work 24×7.

  • Is there a minimum capacity required for a solar power plant to have a monitoring system?

There is no minimum solar power plant size requirement for a monitoring system – these systems can be used in a solar power plant of any size. However, from a benefit perspective, these monitoring systems provide the most benefits for large solar PV power plants than for very small rooftop systems.

For instance, you might not require a monitoring system to tell you that one of the 5 panels on your house rooftop is not working – you will be able to detect it simply from the fact that you get much less output on a sunny day! But for a large solar power plant with thousands of panels, such manual detection will be very difficult.

  • We had an interesting question from a student in India (Sukriti Yadav sent an email to us Jun 3, 2015) on what types of projects students can do in solar monitoring systems.

While of course, there is no one answer, we feel that if you are a student from the computing / information technology major, you might want to think of creative ways to integrate of SCADA with mobile and even perhaps wearables such as smart watches, so that a solar power plant owner can get to know about the status of solar power generation through simple notifications on his or her Apple Watch!

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