Sunlight or solar energy can be directly used for heating and lighting homes, businesses etc. At a time when global climate change has become a serious threat to planet Earth, solar energy is a highly efficient source of "clean energy". In line with the Indian government's push for clean energy, and as part of its "Green Campus" initiative, IIT Bhubaneswar has installed solar power generation system.

 

Conceptual Design

 

After site survey on each identified building rooftop and based on the available space, capacity of solar rooftop generation on each building has been calculated for installing panels. It is based on the fact that average solar panel is around 17.6 square feet and produces 265 watts under direct sunlight per day, equalling out to 15 watts per square foot. For example in guest house building, Stringing design S1, S2 and S3 consisting of 2 strings of 17 no’s 300Wp modules with MPPT (Max Power Point Tracking) capability has been considered. These 3 strings with suitable single core cables has been connected to 3 number of Delta make inverters with 10KW rating. The inverter has communication capability to communicate with data logger device on either GSM modem or LAN interface to cloud computing system where daily generation data is logged. All the strings and inverters are earthed to ground.  The inverter output is connected to AC sub junction box using 3-phase 4-wire copper cables. The AC sub junction box helps in connecting AC output to 3-phase bus bars with neutral using 32 A 4-pole MCB for safety and protection. The bus bar terminals are further connected to meter box with 100 A 4-pole MCCB. This MCCB can connect/disconnect the entire solar PV generation unit from grid based on the conditions on grid side. The energy meter installed by CESU measures the amount of solar generation for accounting purpose using a 100/5 A 0.5 class CT with a burden of 10VA. The solar PV output is connected to the grid at 400A incomer using AC distribution box with suitable protection mechanism.

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