DavidO said:
I have to ask the question why a 160 watt solar panel. Is it because FWC does?
I have a 160 watt Grape solar panel and it work great so while it is a good choice it is not what I would chose today. The reason that I have a 160 watt panel is that was the highest watt rigid panel that was a 12 volt panel at the time. My panel and mounting hardware comes in at 26 pounds and that replaced a 17 pound 95 watt factory panel. So only 9 pounds added. If you were to a 24 volt panel the weight goes way up fast to around 40 pounds.
Today there are several 12 volt panels that are 180 watts they weight the same as the 160 watt panel and are about the same dimensions. Though 20 watts is not much every little bit helps.
The question comes back to which 180 watt panel? I tried Amazon but $300 shipping was crazy. Looking farther you can get a 180 watt Grape Solar Panel at Home Depot for $258. I'm sure that there are better deals to be had with further research.
David,
Keep in mind that:
1) Your solar controller may drastically limit how much of that power you get to use. I looked up those panels on GrapeSolar.com The 180W US made version puts out 19.67v at 9.15A to make 180W. The typical (PWM) solar controller fitted to our campers from the factory will only make use of a nominal 13.8V (fully charged AGM battery) + 0.5V = 14.3V to push the charge into the almost full battery = 14.3*9.15 = 130W.
2) A MPPT controller will try and make the max power, and so get more of that 180W into your batteries.
3) The most you are likely to see is 80% of rated power getting to your batteries, given practical realities of dirt/shade/temperature/angles, etc
4) The reason for #1 above is because a PWM controller will literally "toss away" higher voltages, and this is why a "12V" panel typically has their cells arranged to limit voltage and maximize current. Thus, a 12 V panel that makes 10A at 15v = 150W will push more power into your battery via a PWM controller than a 150W panel that makes 25V and only 6A.
5) Given the 80% rule mentioned in #3 - and combining it with the max voltage you can make practical use of = 13.8+.5 = 14.3, can see that you will want a panel that makes the most power at 14.3/80% = 18v. That means a 180W panel that puts ouf 180/18 = 10A.
The Grape Solar panel under discussion is pretty darn close, at 9.15A.
I hope that helps you in your shopping for a panel!