I also think those panels are over priced. I bought 250 watt Kyocera
panels last year for $250/each. I don't know anything about the Grape brand of panels, but Kyocera
has a 10 year warranty and good name.
I am not a big fan of the Solar Boost controller. I have one on my RV (which has two 120 watt panels). The terminal block seems a bit rinky dink and not suited for large wires. The metal face also gets worryingly hot. It still works fine, but for the boat I used a Morningstar Tristar-MPPT controller
, which has a big heat sink, better diagnostics and more advanced configuration (for charging
voltages and automatic equalizing and etc), a higher quality terminal block (that accepts large wires), and overall just seems higher quality.
I don't agree with everyone else about getting a bunch of smaller panels. I feel that's just more connections and bolts. I think you should keep in mind when you mount the panels that, if you break them, years from now you may not be able to get a new panel with the same dimensions. So, if possible, mount them in a way that there's a little room for adjustment. I would also leave room for more panels (by putting them to the side instead of the center, for example, to leave a big space for more), if possible -- I feel 500 watts may not meet all of your needs. But 750 or 1000 watts may.
We've recently gone from 'too little' to 'way too much' solar, and it's a nice lifestyle improvement. To not even worry about energy any more.