Solar Trickle charger

I have a Deltran 15 watt charger and it is top of the line. It will keep either the house or the chassis batteries topped off if fully charged when applied. It was very expensive+- $150. If I were to buy mow, I get at least 30 watts. Google Solar battery charges and compare. For $150 I could make one from the wires and battery clips to the controller and a 60 watt panel.

I have no other personal experience, just stuff I've gleaned from the forums.