270w solar world panels

I made a mistake when I bought our 185W 66 cell high voltage panel to use on our teardrop trailer as it was intended for a grid tie system and puts out 70+V no load. This required an MPPT controller and the Morningstar would handle the voltage. The outcome is we get usable power from sun up to sun down and in shaded camp sites. I have seen it put out 36V in shade and 17V under a full moon.
A good discussion http://www.victronenergy.com/blog/2014/07/21/which-solar-charge-controller-pwm-or-mppt

sportzfann wrote:
I need to do a power assessment of how much wattage I need.

That's good place to start. However, unless you never park under a tree or cloudy sky or increase the wattage you need, plan for the biggest system you can put on your roof.

At the very least wire for that "biggest system" as rewiring can be a major PITA.

well not a big one at least. ;)

sportzfann wrote:
I don't want to get a expensive inverter and run wire for a/c and microwave.

Nobody runs a/c on batteries. And you don't have to run wire either.

Once you're at home, you'll have time on your side. A single 140w panel would handle that no problem, provided it's well exposed. And depending on the amp hour capacity of your bank, it may even work well for equalizing occasionally.

If you think you may do more boondocking in the near future, you can always go with a 30a pwm controller, and have room to add another 140w panel in the future. Just one more thing to consider.

Take your time. Prices are only coming down.

Wow, thanks for all the responses. I need to do a power assessment of how much wattage I need.
I wanted to have a system that will charge my batterys completely while at home.
And be able to run for a week without my genny or hookups. (just don't want to hear it), and I like the more remote locations. If I need the a/c I do have a pair of Honda generators. I don't want to get a expensive inverter and run wire for a/c and microwave. sounds like I need to do some more research......

I agree with BFL, you can easily camp with just batteries and gen charging for a week. Some people don't like to run the genny that much though and that's what makes solar interesting. That said, you can even eliminate running the genny for that week too (assuming you have one). My religion does allow running the genny too (I use it for the convection oven) but I'd sure love to not use it at all. Call it an engineering exercise.

I've been pricing out my portable 12v system, and I'm looking at (incl. taxes and shipping), about $500 canadian... for two 140 watt panels, 50' of + and - 6ga cable, all connectors, and a 30a pwm controller.

So how good of a price is a good price?

We can go off grid for two weeks in a row max with no solar. However, our religion allows the use of a generator to run a battery charger every second day for two hours at a time. That is not much gen time in a week.

With no solar, "progressive capacity loss" from doing 50-90s every second day gets so bad we can't get through the night by then, and we need shore power for a couple days to do a "recovery" on the batts to get them back to baseline SG.

Solar (230w for us) now lets us go for five summer months in a row off grid no sweat, including the odd gen time if the weather is bad.

So based on that I still say the OP can get by with no solar for a week and with a little solar he could do very well for that week. Assumes he has at least a 1000w gen and a 45amp charger or similar. More gen and charger is better.