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DC Coupled PV System - Design and Best Practice Query

Started by Jahanzeb Tariq, July 17, 2017, 12:51:16 PM

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Jahanzeb Tariq

I had a query about the design of a DC-coupled Solar PV System that incorporates First Solar PV Modules, Solar Charge controller- Conext MPPT 60 150 along with Schnieder Conext XW+ 8548 E inverter/charger.
The maximum input voltage (temperature corrected), of the charge controller, is 150V as per the data sheet. We're using First Solar 117.5W PV Modules (Thin film Cd-Te). The Open-circuit Voltage of one such module, at STC, is 88.2V (and 1.79A Isc) and after Temperature correction becomes 96V. This leads us to designing a string that only has one PV Module in series while around 27 PV modules in parallel – for one charge controller.
Physically, the PV Source circuit will require a combiner box where 27 Positive and 27 Negative wires from each module will be combined (parallel connection) to form a single positive and a single negative output that will be fed into the Charge controller.
The total Open-Circuit (temp corrected) Voltage of the string will then be 96V and the total Short-Circuit current will be (1.79 x 1.25 x 27) 60.4A.
My question about the mentioned design is, is this the standard way of designing a DC-coupled system with this Charge Controller and PV Module (Thin Film – CdTe), that results in such a high current and a huge number of conductors to be run through the conduits and combined at the Combiner Box? Is there any standard or Best practice in the industry that recommends Design and Implementation of the System using the mentioned methods? Are there any reservations by Schneider about the mentioned Design?
I am looking for an international standard or a best practice to benchmark this design and its implementation so as to eliminate any efficiency and safety hazards.
Your help is much appreciated.

Jahanzeb Tariq