Solar trickle charger for chassis battery......Good or bad?

I have a truck and trailer. And since the trailer has solar I keep them connected. I have the Trik-L-Start connected over the truck isolation relay. Works perfect.

20 watts might be too small for a large set of batteries or too large for a small start battery depending on how much sun you get. May want to monitor the situation a bit depending on conditions. I had 15w maintaining 4 batteries and it was never really enough even in sunny so cal.