When you purchase a photovoltaic power plant you should dimension everything according to the nominal power of the system, or rather according to the power that the system manage to produce in S.T.C. conditions (1000W/m², 25°C with sun spectrum AM1.5). We expect to produce this power with good consistency over the life of the plant.
Often it happens that this information remains a value on the paper. But which are the factors to consider to bring the performance of the system to the nominal value?

• Positioning of the modules: Pay attention to how the photovoltaic modules are being positioned by considering and making the project according to the place of installation. In particular you should consider:
  – Possible objects that can create shadow effects;
  – The inclination and orientation of the modules;
• Partition of strings: For big systems it is a common practice to divide the modules in several strings with the purpose to limit the maximum string tension according to the limits of the inverter. Moreover it’s important that the modules connected in the same strings are of equal power and installed with the same inclination and illumination conditions. Otherwise you risk to compromise the performance of the entire string. For critical installation conditions you canoptimize the performance by installing micro invertes or particular junction boxes on the single modules.
• How to optimize the work of the inverter: The efficiency of the inverter varies according to its working conditions. A general recommendation is to make it work close to the nominal power. In any case it is important to control the performance curves present in the manual and the switch on point.
• Don’t walk on the modules: This can sound like a strange recommendation but often it happens, for accelerating the installation work, to not care about the photovoltaic modules. The front glass of the module is resistant and robust, optically damages are not shown even if you walk several times on top of the module but this stress and transport negligence can generatemicro cracks that with time can create “snail track” or create zones which no longer are generating power. According to our experience this is one of the factors that mainly influences the performance on long term basis. This phenomenon is visible only with anelectroluminescence camera.
• Quality wiring: Photovoltaic modules are generating current and even though you try to raise the tension by putting the modules in series, the current that pass through the cables is very high. For this reason, a careful choice of cables, wiring and distribution system helps to minimize the transmission losses. Mind in a particular way the cables and wiring that convey several strings.
• Dirt: Everything that comes between the sun and the cells reduces the quantity of light received and converted by the photovoltaic modules, therefore dirty modules can reduce the efficiency of the system. For this reason, according to the place and the climatic conditions, we recommend to foresee cleaning maintenance of the systems. Products are available that limit the dirt adhesion on the glass, but also in this case we recommend to evaluate the extent of the investment.
• Supervision: Monitoring a photovoltaic installation doesn’t add neither remove efficiency from the system but it is a valid tool to keep under control the produced power and the various operation parameters. This consents to have a history of data and moreover it permits to measure the effectiveness of the performed improvement operations. A supervision system alerts you also if something happens and if it is necessary to intervene on the system.

The maintenance of the system is the operation that permits to make most profit out of your investment.
Ecoprogetti, thanks to the competence in the photovoltaic industry, can perform aimed consultancy service to optimize and verify the efficiency of your system.
Contact us for technical advises and visit our web page to know more about the services that we are offering.