Please find attached

[Joj]

What are the sentences that I can use while I'm sending an attachment.
Please find attached the electrical diagram of the PV installation that will be installed in X's house.
Please find attached the structural drawing that will be mounted on the roof of Mrs. Y' roof.

 

[Tarheel]

What are the sentences that I can use while I'm sending an attachment?
Please find attached the electrical diagram of the PV installation that will be installed on X's house.
Please find attached the structural drawing that will be mounted on the roof of Mrs. Ys' roof.

Use the first one. (I'm sure you're not going to put a drawing on the roof.)

 

[Joj]

Please find attached the electrical diagram of the PV installation that will be installed in X's house on Thursday 28th of April.
The client's electrical panel is composed of 30Amps.
We will install a 10 amps PV system.

 

[Tarheel]

Please find attached the electrical diagram of the PV installation that will be installed on X's house on Thursday 28th of April.
The client's electrical panel is configured for 30 amps.
We will install a 10 amp PV system.

I think that's right, but if I were you I'd look up "configured" just to be sure.