Ok well good that we got that out of the way. lol
We have solar and are thrilled with it. It isn't a brand name system like zamp or go power. It is a collection of parts that fit our needs. we take 230w for the trailer and three times as much to run a big inverter and bank.
18-30w is pretty small. Close to the range people use to keep their battery from self discharging in storage. One rule of thumb is a watt to a watt and a half per Ah of battery. 50 Ah is not much but 18w will do little if it gets low.