Dear Mr. PK Pandey
Since you are availing the exemption form payment of excise duty under Notification 50/2003-CE, you are no need to issue the form ARE-1. You are out the purview of excise net . You can not claim or charge the cenvat.
The issuance of Form ARE-1 are needed for those who are in the tex net. For availing exemption excise duty for export (including supply to SEZ), they furnish the LUT with department and provide them Proof of export within a stipulated time.
Since SEZ unit is located in India and you are also in India, then you can clear the goods under exemption to SEZ..
Hope the querry is resolved.