After several hours of trying and exercising the Explorer works now. (jippii)
It was not that easy for me as a beginner, so for those who need some hints:
Since TLS is in my dev environment not necessary, change grpcs to grpc in the config.json :
"peer1": {
"requests": "grpc://127.0.0.1:7051",
"events": "grpc://127.0.0.1:7053",
"server-hostname": "peer0.org1.example.com"
and change to path to your running fabric composer keystore and certificate: /fabric-scripts/hlfv1/composer/....
"admin": {
"key": "../fabric-scripts/hlfv1/composer/crypto-config/peerOrganizations/org1.example.com/users/Admin@org1.example.com/msp/keystore",
"cert": "../fabric-scripts/hlfv1/composer/crypto-config/peerOrganizations/org1.example.com/users/Admin@org1.example.com/msp/signcerts"
}