Eliminates the P.I.D. effect in PV systems

• Stop the power loss

• Stop the economic damage

• Restore after 30 days

• Prevents P.I.D. effect

• Measure the insulation resistance

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What is P.I.D. and what are the plants at risk

P.I.D. (Potential Induced Degradation) indicates the phenomenon of degradation and power loss in the PV modules, problem highlighted especially in the last decade, following the elimination of the output transformer in the inverter. The transition to Photovoltaic systems of ever greater dimensions, the use of strings with increasingly higher voltages, has led to have negative voltage (with respect to ground) on the cells  such as to induce this phenomenon of polarization, which leads to the progressive switching off of the modules, resulting in important reduction of the performance of the entire system.

 

Example of a PID risk plant

If the inverter is transformerless, PV strings are no longer anchored to the ground and then the negative pole can go to negative voltages with respect to ground ,  giving rise to PID effect.

 



 

Economic damage caused by P.I.D.

 



The P.I.D. effect, can distort the Business Plan calculated in step design of a photovoltaic system, with very serious economic consequences. This simulation is relating to a grid connected 200kW plant with the second energy bill in 2010. It shows a power decrease due to P.I.D. (Up to - 70%). This issue moves Payback (ROI: Return on Investment ) from seven years originally planned to over 17 years, reducing the proceed accumulated after 20 years to such a low level , not to justify   the initial investment.

 

Before and after the treatment with APID

P.I.D. effect consequences on photovoltaic modules:

• Polarization of the PV cell

• Electrocorrosion of the TCO layer (transparent plastic Conductive Oxide).

 



 

APID General Description

APID is a high voltage generator developed for the restoration of photovoltaic modules affected by P.I.D. and for the prevention of this phenomenon. APID has two outputs for MPPT inputs. It is connected like a PV string , in parallel to the strings with PV modules affected by P.I.D. No need to disconnect the Inverter because the maximum output voltage generated by APID to Ground  (1000 VDC) is within inverter insulation limits and the output current does not exceed 8mA. APID is fully automatic in both the operation and the management of the output voltage of the PV fi eld. During the day APID detects the voltage on the PV fi eld and remains in standby. At night it generates a voltage equal to that detected during the day in order to create an equal and opposite action, at Sunrise APID returns to standby.

 



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APID is a comprehensive tool

1. INTERACTION ON THE FIELD

By means of the display and keyboard LCDAM08 is possible to alter the fi eld of the operating parameters and read: day string voltages, output current, power generated by APID, the insulation resistance to Ground of the plant , the history alarms  up to 100 messages.



 

2. HISTORICAL VOLTAGES - ALARMS

APID is capable of recording a historic of 1 month with frequency “every fi ve minutes”, or 1 week, with  frequency “every minute”, of  the voltage of its internal generator and the voltages (with respect to ground) on positive and negative poles of the strings, with an accuracy of +/- 10V.

 

3. REMOTELY  SUPERVISION SOFTWARE

APID Modbus Monitor is a software supplied with the APID system for direct remote monitoring, downloading of the alarm history and the voltage history of the string , through serial port RS232 / 485 and ModBus Protocol, also through GSM modem.

 



 

APID evolves  with the new release APID GRAPHICS. As well as prevent and restore the phenomenon P.I.D. in PV plants ,  with this Software APID also becomes a powerful diagnostic tool, with data logger functions, generates graphs of historian voltages both day and night.

These graphs indicate whether the PV plant  function properly or if there are irregularities, such as:

 

• Inverter Abnormal Shutdown

• Abnormal voltages on strings

• Correct operation of APID

• Predisposition to  P.I.D. phenomenon

• Insulation Losses to ground

 



 

Main Technical Characteristics of APID