RESPOND QUICKLY I need Ideas for a highly efficient hydrolox kickstage that is under or at the weight of 1.5 metric tons.

I need Ideas for Fission, my next kickstage. I highly recommend that solar panels should be included in your idea. The engine needs to be small, but not too small that it can't move the kickstage or the spacecraft. The fuel used should be either monopropellant or hydrolox. The kickstage should be very efficient. I am looking forward to reviewing your Ideas! Note: There needs to be no tinker panel required.