Question on my new solar install

I had a new solar installation put in today, I had x13 panels at 405w put on my house and x20 405w panels put on my garage, the house is south facing but the garage is east/west. I was quoted for x2 sunny boy 5kw inverters but they installed x1 5kw and x1 3.8kw after i asked why they didn’t install both inverters as per quote, the solar designer called me and said because the garage faces east/west it isn’t going to reach the full peak potential and it is better to put a undersized inverter as opposed to a bigger one due to the amount of watts and the inverter running better at full capacity rather than less. They said they will deduct the $ amount of the difference in cost between the two sizes, does this seem right? I have a roughly 13.4 system with only 8.8kw inverter capacity.