APID
Eliminates P.I.D. effect on PV modules
When use APID:
APID restores the performance of PV modules degraded by PID effect;
APID prevents the PID effect of PV modules at risk.
What is P.I.D.?
P.I.D. (Potential Induced Degradation) indicates the phenomenon of degradation and loss of power of PV modules, highlighted especially in the last decade, following the removal of the output transformer in the inverters. The shift to photovoltaic systems of increasing size, the use of strings with increasingly higher voltages, has led to tensions on the cells compared to the ground, with negative values enough to induce this phenomenon of polarization that lead to progressive switching off of the same modules, resulting in significant reduction of the performance of the entire system.
Description and Operation
APID is a high voltage generator developed for the restoration of Photovoltaic Modules with PID, is connected like a string of modules, thus is located in parallel to the strings to be regenerated, not normally necessary to disconnect the inverter as the maximum output voltage generated from APID to Ground (1000 Vdc) is within the limits of the inverter isolation and the output current does not exceed 8mA. APID is fully automatic in both the operation and in the management of the output voltage of the PV field, during the day APID detects the voltage on the PV field and remains in standby, during the night generates a voltage equal to that detected by day in order to create an action equal and contrary, at dawn APID switches to standby.
APID is connected from one side to the network at 230Vac and the other, in parallel, to the PV modules and therefore to the inverter input, but does not take power from the electrical network to put it into the inverter input. APID produces a potential difference between the + pole of the strings and the ground (and not between the + and - poles of the strings) up to 1000v with a maximum power of 3w, the difference between the + and - poles is actually only 20..30v and is caused by the voltage drop due to the internal resistance of the modules, a too low to start the inverter. In addition, the connection between APID and the - pole of the strings takes place internally via a series of resistances for a total of 31 Mohm thus limiting the current passing through to only 32 uA obviously insufficient for switching on of the inverter.