[noelex 77]

Originally Posted by corkscrew

So should I add a fuse? Maybe between panel and controller on the hot line? How should I choose the fuse size? Is it a certain size per watt or amp?

Its the Amps that are important for a fuse. A 2A fuse is correct for your 20w solar panel mounted close to the battery preferably fuse both + and -.

Also, with reference to amps and batteries and power consumption. My group 29 has like 125 or so AH. My understanding is that you simply add the amp draw up for all your stuff and that gives you the amps per hour you use. So if you have a stereo and a VHF radio that each draw 5 amps....that will be 10 amps an hour....so I could run them both for about 12 hours before my battery drained correct?

In theory to drain the battery completely yes, but the battery is not likely to be 100% charged and for various reasons it will not meet these theoretical claims. Its real capacity is probably 100AHRs, but for reasonable battery life it is better to restrict the discharge to 50%. So you have about 50AHrs to play with.
The good news is the power consumption of the VHF in recieve is only likely to about 1A and most "car "sterios are about 1 to 1.5A

The solar panel return amps to the batteries......extending my time. AM I on base here?

Yes . Depending on the time of year location etc the output will vary enourmously, but about 5Ahrs a day would be an average

Cheers John