Originally Posted by smp
Indeed! A 20 watt panel will not be up to snuff, the 85 that I'm considering will... and it's half the price of the 20 watt name brand setup.
As has been said you get what you pay for. Rather than buy a Chinese "MPPT", which is likely not even MPPT at all, why not buy an inexpensive Morningstar PWM controller like the SS-10.
Your MPPT benefit on an 85W panel will be so minimal as to barely be worth it and you'd be better to just throw that money at array wattage anyway.
Just grab a Morningstar SS-10 12V for under $50.00 and call it a day. You'll get a quality product, humans you can talk to, and it will hold up in the marine environment and do as is says it does. These are excellent little controllers for the money. Search around and you can get them pretty cheap...