Monitoring of PV plants ENERBUILD

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For the ENERBUILD project, PV plants have been monitored in two regions, Alessandria and Vorarlberg

General information

Producing energy on ESAP buildings implies, most of the time, to develop PV plants on the roof. Such systems are almost standard now. An important point in this context is the investment security and reliability. The aim is to protect energy producers from negative surprises, such as disturbances to production failures. Experiences show that failures have to be expected. Actually, according to surveys and discussions collected in the preparation of the project in Vorarlberg], production losses occur in the order of 10-20%. The failures occur because of damage caused by marten bites, by shadows, by failures of individual modules and by disturbances in the rectifier. Since the plant owners usually have no possibility of comparison, the creeping partial failures are hardly recognized. The total failures are detected sooner, because the plant owners, not every day, but with opportunity (monthly or semi-annually) check the system display. Partial failures or partial blackouts are only recognized with the year-end accounting. Usually, the damage is already very large then. Also, annual comparisons are sometimes difficult, especially as the weather conditions are different over the years, so with a creeping deterioration it is difficult for the operator to draw conclusions about technical flaws. What he is missing here is the direct comparison system. Without a direct comparison system such errors cannot be truly determined.


Alessandria: Monitoring of PV plants


In Provincia of Alessandria’s land in these last years many PV plants were built. The monitoring done by Provincia of Alessandria was conducted on 6 plants, and each of them differed from the others by size, by type of installation and by kind of users. The plants were monitored under direct inspection at the installation site.

The second step was to acquire data for monthly production of electricity. The data for the production of electrical energy on a monthly basis are presented in reports that indicate the production of electricity during the year. These data are comparable for the different types, both for performance throughout the year, and for specific production (kWh/kWp).

n. Plant Place Capacity (kWp) Type Production (kWh/kWp)
01 RAL Srl Alessandria 7300 On ground 1210,19
02 Protalupi Spa Ticineto 61,54 On roof 1.014,27
03 SRT Bosco Marengo 99
04 SFIAL Srl Alessandria 59,4 On roof 1.189,55
05 Liceo Scientifico "B.Pascal" Ovada 14,52 On plan roof
06 UNI Capi Scrl Alessandria 20 On roof 1.177,96
On face of building 735,13

Illustration with results

As sample we present the largest PV plant visited - RAL s.r.l. located in Alessandria – and the plant conducted directly by Provincia of Alessandria – Scientific Lyceum located in Ovada.

During the monitoring we tried to detect possible information regarding component costs of PV systems and their installation, for improving the system method to other realities on territory.

The costs are usually expressed in terms of Euro / Wp, referring to a „type-plant“ (electrical and electronic components, mechanical support), net of preparatory construction work and working conditions required by any specific details; this to facilitate comparability among different types of plants (mono-multicrystalline; inverter with or without transformer, fixed or with solar-tracker).

From information obtained a reduction in costs due to the strong increase in installations has been found since the years of the incentive scheme called „CONTO ENERGIA, restored in Italy in this last years and also developed for next years.

For other applications we must remind that he cost of installing the PV system depends mainly on the electrical and electronic components, mechanical structures of support and preparatory constructions are specific, variables and related to the real operating conditions:

  • roof installation does not require high support works, if the structure is efficient; however it requires the prior realization of structures for protection against falls from a height that, in certain situations, may be an important factor;
  • installation on the ground is the most immediate but supporting structures solidly anchored to the ground are required, and the mechanical characteristics are variable and depend on the nature of the soil (agricultural soils, landfills, etc.);
  • wall installation to integrate architectural façade (mostly vertical) of building involves very different costs depending on whether panels hang directly on the wall (type RVF) or outdoors (structural) for the different incidence of structural steel supports and anchors consequently requested.

In general, no particular critical issue was found.

For other applications it should be pointed out that the incentive system in action („Energy Account„) pushes constructors and those plant managers to plan the construction of plants through high-profile quality standards very carefully in order to minimize potential economic losses; all this for the final benefit of the producibility and reliability.

Special attention of the plant managers was given to modules steals, a problem present in the monitored area.

This resulted in a widespread application of protection systems also of various types:

  • high-tech security systems, perimeter sensors, supplemented by video surveillance (camera unit and transmission cable IP solution and / or wireless);
  • protection systems with optical fiber cables;
  • protection plants (mostly mechanical) with systems of locking bolts.

For more information, please contact:

Studio Tecnico d’Ingegneria

Ing. Chiara Cassulo

+39 0131 251834

Environment Park

Arch. Stefano Dotta

+39 011 225 71 11

Provincia di Alessandria

Ufficio Tecnico Edilizia

Ing. Piergiuseppe A. Dezza, Ing. Andrea Sacco, Arch. Marco Palavicino

+39 0131 304600


Vorarlberg: Monitoring of PV-Plants

This article deals with the monitoring of PV plants in Vorarlberg. Within the ENERBUILD project, PV plants have also been monitored in Alessandria

Description: Context of the work on monitoring

The development of a pilot monitoring tool in Vorarlberg was motivated by several reasons:

• Existing monitoring devices of PV are mainly proposed by manufacturers, meaning it’s hardly possible to compare plants established by different companies. Only 2% of the plant operators monitor their plant by the manufacturer.

  • Web integration of data from monitoring systems is complex and technically not easy to handle for small private producers. Different technologies and standards make a re-liable data transmission difficult.
  • Due to the lack of independent and comparative measurement, it is hardly possible to pursue manufacturers in terms of performance. Whereas big failures can be easily identified, gradual deterioration or poor modules are hardly detectable.
  • In the total of all plants production losses, 10-20%. exist because of damage caused by marten bites, by shadows, by failures of individual modules and by disturbances in the rectifier.
  • There is the need to increase producers’ reliability in electricity production. In Vorarlberg it is therefore desirable that the monitoring system will be part of the founding scheme.
  • The implementation of a monitoring concept supports the creation of a „producer community“. The producers should be able to mutually compare their plants. By comparison, the systems should raise playful competition between plant operators and raise awareness for the maintenance of plants. More generally, communicating on the system performances and preventing more accurately their failures contributes to encourage people to invest more in RES plants.

Objectives within the ENERBUILD project

In Vorarlberg, 1.100 photovoltaic systems are mounted, 30 systems were installed more than 10 years ago. They benefit from a feed-in tariff that is either signed with the Austrian public company OeMAG or directly with regional electricity distributors. The average size of plants is 4,9 kW. These are often small or micro-plants, built of small businesses and homeowners.

There is a huge potential to improve the running of PV systems. It can be assumed that the improvement in the context of Vorarlberg could represent no less than 560.000 Euros. In the frame of ENERBUILD, not all of the potential can be achieved but in the long term, at least 50% of the potential should be reached by avoiding failures. The objective is to increase productivity by at least 280.000 Euro per year. The investment in improvement measures should not be more than 15% of the total improvement potential. 10% of existing plants in Vorarlberg should be connected with the monitoring system during the project period. Subsequently, during the period of 5 years, 30% of all plants should be reached. In addition, 90% of all new upcoming plants should be connected to the monitoring system.

Illustration with results

Independent technology from suppliers of PV

To realize a technical concept independent from the manufacturer it was made possible to compare different plants with each other during operation in a standardized way. For the monitoring a data logger (counters, pulse converter) including a data transmission device was installed at each plant.

Uniform data collection and transmission technology

Consistent data collection and transmission is a particular concern of the concept, from past experience especially this caused most disorders. The standard is implemented starting from the power meter. Up to four different counters can be recorded and transmitted, e.g. Electricity supply and delivery of electricity, domestic power consumption and others. The transmission technology is based on cooperation with a national mobile phone operator using a standard data GSM SIM card. The transmission takes place every hour with 1kB data volume (100 to 2.000 pulses per kWh). The web based monitoring (cloud-computing) makes the installation of additional software at producer or consumer side needless.

Photovoltaic benchmarks as monitoring principle

The benchmark is a reliable comparison of performance under the same conditions (calculated and harmonized on kWh per 1kWp). This enables to compare up to four PV systems from various constructions and dimensions. Discrepancies over time can be reliably identified as technical performance deviations. Weather conditions do not matter, since the systems were compared under identical conditions. For example, the nearest plant concluding weather-related deviations and plants with similar orientation give information about the relative performance of the plant itself. Sudden deviations to the compared plant clearly indicate damage.

Coupled with the Eco-Power Stock Exchange

The realized concept is deliberately coupled with the Eco-Power Stock exchange. The green power market is an existing internet-based system that lists the eco-power plants for the direct promotion offer of green power. Due to the fact that the data is already collected in the system, the monitoring concept refers to it.

Application to other regions - Capitalization

The monitoring as a technical system is vendor independent and can be operated without installing any software. In combination with the funding scheme of the Eco-Power Stock-Exchange, the 100% web-based solution allows an active development of a „consumer and producer community.„ A transfer of results to other regions and countries is possible without problems.

Service offer: Cost to participate in the monitoring system

Investment (net) Euro
Acquisition data logger: 390
Installation in new plants 40
For existing plants around 250
Data transmission, SIM card 20
Operating contributions / membership fees - listing in the system 15
Benefit for the plant operator Additional funding from the green electricity market per year: Euro
Community support accounts (1/4 of all communities are already green sponsor) 20
From direct-steering (2 households) 64
Avoidance of system failures: (10% estimated) 190
Average plant output 4.9 kW/h
Annual power:

4,9 kW/h * 1.300 (max service hours/year) = max solar radiation 6.370 kW/year. Estim.: 4.900 * 30 cents = 1.911,- * 10% = 190,-

It may be argued that the payback period for the investment in the monitoring will be less than 1.5-2 years.


AEEV Arbeitsgemeinschaft Erneuerbare Energie VLBG

Hof 19

6861 Alberschwende

+43 664 8866 7424