I suppose 25 amps at 13.8v is better than 4 amps at 14.8v but if you go past the alternator and just have the solar, the 4 amps is not enough to hold the batts above 13.8, so the alternator would keep providing amps I guess. I have no idea how that really works, so some tests would soon tell the tale. You would need to get the batts way up in SOC for the solar alone to hold them above 13.8v
Of course in the summer, solar does much better in amps so it would not hurt so much if it did overtake the alternator's contribution. Also in my case the alternator amps is not as high as many MH owner's on here report they get--no doubt with fatter wiring etc. Anyway, lots to check out in idle moments (if there are any of those! )