What kind of hardware do you use for the communication (link)? Is it the TTL-IR-Read-Write head? Please post the sketch you use for the tests. Is it possible to use the hardware serial for the communication to the smartmeter?
According to the specification for the A1500, the data format is 7N1, are you sure it has to be 7E1? Some of the devices seem to insist on the device address, did you try that too?
I couldn't find any information about the IR interface. Usually the the data bit stream is modulated on a base frequency to eliminate ambient light interference.