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Photovoltaics monitoring

The economic honeymoon is over for solar power. In the foreseeable future, photovoltaics will have to make do without feed-in tariffs at

fixed price levels. Regardless of whether operators opt for direct marketing or self-consumption models – more than ever before, they have to ensure that every single kilowatt-hour is harvested. This requires comprehensive quality management, not only from the manufacturer and installer, but also from the operational management. Every kilowatt-hour not produced is cash money subtracted from the balance sheet. Operators are therefore leaning toward solutions which provide comprehensive service which goes far beyond the simple monitoring. Although the demand for all-round packages has been increasing sharply over the past few years, it started from a very low level.

More than just keeping an eye out

Despite the potentially fatal consequences to the per-formance of their systems, many plant operators are utterly unconcerned about plant operations. There is no other explanation for why – according to the infor-mation of services experts such as Wolfgang Hofstetter, the head of the technical operations man-agement at Actensys GmbH – more than 90 % of PV systems are not remotely monitored. This attitude is clearly having an impact, according to Hofstetter: “We meet lots of potential customers at Intersolar with all kinds of hardware and software problems.”

Many operators are already talking about the mounting pressure from banks and insurance compa-nies. In Germany it has now become impossible to insure a utility-scale PV system without remote

All the bellsand whistles

Electroluminescence method for module testing without dis assembly in daylight (Daysy) Photo: actensys

If you believe the monitoring specialists, then only one of ten solar farms

has a monitoring system. Operators interested in remote monitoring should

reach directly for the state-of-the-art solutions. Overall concepts – from

planning to operations management – are the order of the day.

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Photovoltaics monitoring

monitoring or even technical operational manage-ment. Pressure from the banks and insurance companies aside, operators have to monitor their power plants in their own best interest. Their already narrow margins shrink even further in the absence of monitoring. A study conducted by the Fraunhofer ISE indicates that PV systems which are actively monitored achieve approximately 4 to 6 % higher yields. A back-of-the-envelope calculation provides a nice shot of motivation: at annual revenues of € 10 million, this improved yield equates to up to € 600,000 of added revenue – that is enough for more than just a company retreat.

The yield shoots up even more when operators fol-low the latest trend and opt for the full package. “For large-scale systems, full support makes sense right from the initial planning stage, especially for feed-in management,” says Julius Schärdinger, Sales and Marketing Director at Meteocontrol. If there is a trend in the area of monitoring, it is that simple monitoring is a necessary, but by no means adequate prerequisite for smooth plant operation. The way of the future points far more toward comprehensive O&M packages. Asked what the top service providers have to be able to offer, Schärdinger answers: “The capability to offer full service – from consulting during planning, to com-missioning and technical management worldwide.”

Mobile test benches

Customers are demanding nothing less than a com-prehensive quality guarantee. That, in turn, means adding a link to the chain: transport and storage prior to installation. The final quality control takes place at

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the manufacturer. After that, the performance of the modules is not tested again until after the system is in operation. But by then it is too late; the gap is too big. Technicians installing the panels have to be sure to install modules that work flawlessly, which is why Papendorf Software Engineering GmbH has launched a mobile measuring system onto the market. The SOL.Connect PV Module Meter test bench checks the per-formance of photovoltaic modules before they are in-stalled so that they can be sorted directly at the jobsite. The test bench compares the electrical per-formance of the test module with a reference module. With a purchase price of around € 8,000 the system is an attractive alternative to on-site flashing with the usual testers.Papendorf has developed the SOL.Connect Smart Park Control for the operation of solar farms. It monitors large-scale photovoltaic systems and power plants and regulates them in compliance with the Germany Association of Energy and Water Industries (BDEW) guidelines. The SOL.Connect Smart Park Control com-municates with SCADA central control centres and monitoring portals via standardized interfaces. Stand-ardized interfaces are the prerequisite for integrating the solar farms into virtual power plants.

Mind4Energy and Phoenix Contact collaborate

In the past, communication has been the biggest barrier to connecting multiple solar farms into a single power plant and in the interaction with network oper-ators. The collaboration between the Mind4Energy and Ghent University just goes to show that there is still a need for research. The collaboration resulted in the development of a monitoring portal with a number of different characteristics and benefits:

· It offers full functionality including a dashboard, energy graphs, analysis tools, a reporting tool, alarms and error messages, an operation & maintenance ticketing tool and an export function.

·Analysis and visualization of PV plants can be done easily and at high speed – perfect for installers and plant owners who follow many plants with a small team.

· The system is suitable for medium and large plants, including utility scale PV plants.

· The system can capture, store and visualize all available information from inverters, weather sta-tions, kWh-meters and other sensors. The data is

stored for as long as the account is maintained.

· The system allows the use of satellite data for performance benchmarking.

· Different alarms according to the urgency of the sit-uation are generated automatically with priority to the biggest problems.Mind4Energy’s development engineers say they iden-tified significant limitations in the possibilities offered by many data loggers. They were also often of poor quality and came with a low level of expertise among support personnel. The engineers made a quick deci-sion. “Since the utility scale market is an important market for M4E, we decided to develop our own solu-tion based on PLC technology,” says the company.

Phoenix Contact was the partner that developed the hardware, while Mind4Energy focussed on the software. Specifically, the newly developed logger can measure the parameters of the entire plant or its subcomponents. The values it measures can then be combined with external parameters and evaluated. This technology still has more in common with moni-toring – that is, classic monitoring – than it does with the new, extended understanding of the term. But in the next stage of development, the company has announced that its system will be capable of commu-nicating with the network operator in real time.

Key interfaces

Meteocontrol wants to meet the extended demands of system monitoring, management and control with its new product series, which will go to market in the second half of 2014. The blue’Log X-series has a modular design, enabling operators to connect indi-vidual locations with each other to form a “swarm power plant.” The communication interfaces are crucial. Direct remote control through a live connection is included, as well as direct communication with electricity trading platforms.

Another new feature is improved integration with the Meteocontrol portal solutions. A special technol-ogy enables blue’Log to connect easily to the inter-net, in order to connect with the Meteocontrol servers and establish a live connection. Complicated configurations on internet routers are not necessary.

Ensuring reliable data

The best trained technicians’ hands are tied if the hardware itself does not cooperate – that is, if it

Sun & Wind Energy 5/201482

Photovoltaics monitoring

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cannot process incoming data. The Belgian company 3E has therefore entered the market with a wide range of technical options. Rémy Tasse, the head of the company’s software department, explains: “The SynaptiQ software was developed to be compatible with a wide range of PV systems equipment. Currently, it is compatible with more than 25 different data log-gers and around 140 different types of inverters. That means that no technical infrastructure is needed on site to implement SynaptiQ.” However, using one single datalogger brand for a PV plant’s portfolio with many different brands of inverters can be difficult. The datalogger may not process the data provided by the inverters or do so incorrectly. In that case the solution is in the compatibility of the software.

The demands are high, Tasse explains. He believes that they can be summed up by four points: “First, the reliability of the recorded data – this is far from an easy task. Second, the alarm messages have to be relevant and simple. Triggering an alarm is one thing, but trig-

gering a relevant alarm is another. Third, data analysis has to be faster. And fourth, reporting has to happen quickly and be capable of reacting flexibly to different requirements. Investors want to see results, and the O&M teams want to optimise their work.”

“With its latest developments 3E is following the trend towards the all-round package, Tasse says. “Thanks to several years of track records of datalogger operation in PV plants, we are now in a position to propose not only a software solution but also a pack-age including third party hardware, taking into ac-count the requirements of the user.”

Monitoring is a key technology

How are monitoring systems developing? The short answer is: the range of different solutions is ever broadening. Both for large-scale solar farms and home PV systems there are monitoring systems on the market that combine the major components of

Monitoring of a PV plant using the SynaptiQ solution Screenshot: 3E

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an energy management system into a single solu-tion. Solare Datensysteme GmbH has dubbed its en-ergy management system Smart Home. The system is based on the Solar-Log platform, which offers de-velopers a continuous stream of new features. “These tools give plant owners a feel for energy flow in buildings and helps them to adjust their behav-iour accordingly,” a company brochure promises. In the home segment, the key is coordination of vari-ous power generators with each other – generators such as the PV/heat pump combination, which is particularly popular right now – around a load-based storage system and smart home appliances. Their consumption should be perfectly matched.

When it comes to the large-scale PV systems in the commercial sector, grid stability is far more important. Self-use and direct marketing, in addition

Unmanned aerial vehicles (UAVs) are sometimes called bumblebees in colloquial language. Such equipment does bring to mind the flight characteristics of the insect. But apart from its military meaning, the term “drone” also refers to an aircraft that is increasingly being used for the inspection of facilities which are difficult to access.

UAVs can hover at a particular spot or rotate around a particular location. Although they are not among the traditional monitoring tools, when equipped with mini-cameras and other sensors they can play an increasingly important role in the maintenance of large-scale photovoltaic (PV) systems.

The newfound enthusiasm for drones has emerged against the backdrop of the poor accessibility of PV modules in many large rooftop and ground-mounted installations. Often, maintenance aisles between module rows are lacking, says the PV expert and surveyor Tobias Lebherz. In such cases, the inspectors use cherry-pickers. This is expensive and does not always give access to the desired inspection location. A drone flown right, however, knows no limits.

The inspection drones employ two methods. Visual inspection is performed with a high resolution camera. The pilot controls the drone for a relatively short flight and makes aerial images when me-chanical damage is detected or to document shading conditions. In-spectors can thus determine storm and hail damage, even in hard to reach places. The inspector controls the drones via GPS from a cen-tral unit. The central unit processes the data into films or photos.

Defects that the pilot cannot visually detect show up in a thermographic examination. The key component here is the thermal imaging camera, which shows anomalies in the cells, both in the

thermal image and the normal image. A GPS function assigns a georeference to the pictures that enables “problem cells” to be located quickly.

Using the drone is anything but child’s play. Any commercial use, such as an inspection, must be approved. Furthermore, the pilot has to have special skills and should practice several hours a week, according to the expert Lebherz. After all, the drone weighs about five kilograms and can cause considerable damage if manoeuvred improperly. And last but not least, the pilot is handling an aircraft which costs some € 20,000 to € 30,000 with the camera equipment. (ji)

The drones are coming

Tobias Lebherz believes that drones can offer valuable support, but are by no means a substitute for a detailed inspection. Photo: Lebherz

to grid stability, are the issues at the large scale. Whereas communication between two participants – PV operators and network operators – occurs with big systems, additional players are added in the smart home concept.

What is common to all, however, is the basic con-cept: monitoring as a core function. The current prod-ucts on offer are already well on their way to comprehensive energy management which also includes hybrid systems and innovative storage solutions. This should raise the status of the broad-er type of monitoring – for example, with remote sys-tem control capability by the network operator – into a key technology for the energy transition. In the process, it is likely that solar forecasts will be further optimised as an existential basis for marketing.

Jörn Iken