I easily maintain our TT in our back yard with a 55 W panel with a controller. We have a single 12V Trojan SCS battery and have only propane and radio parasitic loads. I used to have just a 10W panel but I was concerned that it was marginal in the winter or rainy spells. I verify proper maintenance charge by checking the voltage in the morning before the panels started charging. I have been using solar for maintenance for many years. I do check parasitic loads and charging current with a clamp on Ammeter.
Dick