boondocking pnw solar considerations

I just purchased my Northwood Fox Creek and would like to start making plans to be boondocking capable.  I will be by myself most of the time, using basic lights, a few small fans, charging a tablet and phone, cooking with one electric appliance at a time which are yet to be determined and running heat/an electric blanket.  I was thinking of using a 480 watt solar set up (though this is an estimate, I still need to do the actual math).  What I'm wondering is since I'm primarily in the PNW where there is a lot of cloud cover in the winter should I looking at getting something bigger than that to compensate for the cloud cover to make sure I always have enough.  Or could I count on a portable setup to set up as backup on cloudy days?  Are there any manufacturers that you recommend?

To be honest "basic", "small" has really no meaning.  You must know your Kwh needs per day to estimate solar needs.  Also the size of your batter bank to store the energy that supplies your backup for those days the sun is not providing any significant energy.  Then you must factor in location differences.  Spokane in the winter can easily get just 15% of the solar energy that Phoenix gets in the summer.  So panels that put out 480 watts in the summer in Phoenix will likely only put out 70 watts in the winter in Spokane. 

Goggle:  Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors  Solar panel efficiency these days is about 14%.  So every Kw of solar energy reaching a panel yields about 0.14Kw of electricity (of witch lead acid batteries in turn are 90% efficient at storing.

see  http://www.rvforum.net/SMF_forum/index.php/topic,100419.0.html

Here's a good starting point - a solar insolation map from NREL.  Input the month you're concerned about and the mounting position of your panel (flat or tilted) and it will tell you how much solar energy it will collect.  This is the raw solar energy, you'll have to use your panel's rated efficiency to estimate how much electricity you'll get from it.  Most polycrystalline panels are about 15% efficient, for example if your location has 2000 watt-hours (2KWh) of solar insolation per day shining on the panel you'll get about 30 watt-hours a day out of the panel.

Winter months in the Northwest look pretty bleak for solar power.  Panels will produce some power under cloudy skies, but not nearly as much as panels under a full sun.  You'll have that plus shorter days in the winter working against you.

As to how much power you'll get in your location on a particular day, all you can do is give it a try.

Electric blankets, heating and cooking appliances will drain your batteries fast.  If you use a modified sine wave inverter, it can fry your electric blanket. 

We have 6  batteries and 3 solar panels.  We also have a generator..  Unless the generator is running, I don't use any electrical cooking appliances, especially the microwave.  My rice cooker is an exception; it draws very few amps.

Jeannine

I live in NE North Dakota. I have 605 watts of solar panels mounted flat. I get about 230 watts of power on a clear day at noon at this time of year. On a cloudy day about 30 watts. You could tilt and move around portable panels to gather as much solar power as possible,

In addition to what has already been suggested, I would before buying any extra batteries and solar equipment, install a good battery monitor and use your rig, keeping an eye on how many amps you are using over the course of a day.  Then you will have a much better idea of how large a battery bank and solar power you will need.

I have solar and fair amount of battery capacity and can run any electrical except air conditioning.

Air conditioning powered by solar is a pipe dream unless you have above average means to install such a system.

Install the largest capacity solar sytem and battery bank you can install.  If you can fit 1000 watts and 800 to 1200 amp-hours of battery capacity, i'd go for it as that is what I think I owuld need as a minimum for a cloudy PNW.

krista_girl86 said:

I just purchased my Northwood Fox Creek and would like to start making plans to be boondocking capable.  I will be by myself most of the time, using basic lights, a few small fans, charging a tablet and phone, cooking with one electric appliance at a time which are yet to be determined and running heat/an electric blanket.  I was thinking of using a 480 watt solar set up (though this is an estimate, I still need to do the actual math).  What I'm wondering is since I'm primarily in the PNW where there is a lot of cloud cover in the winter should I looking at getting something bigger than that to compensate for the cloud cover to make sure I always have enough.  Or could I count on a portable setup to set up as backup on cloudy days?  Are there any manufacturers that you recommend?

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Here are two links to basic info about RV battery usage & charging, power estimates for some devices, inverter usage, and some info about solar.  The second link is the continuation of the first link so be sure to read both.
http://www.marxrv.com/12volt/12volt.htm
http://www.marxrv.com/12volt/12volta.htm

The info in the links will give you some good info to start planning your batteries and solar. 

In the earlier replies you have been given power usage in watts.  However batteries are rated in Amp Hours (AH).  This is the number of amps used per hour.  So when looking at the info given earlier, take the number of watts and divide that by 12 and you will get the number of amps you will be taking from the battery.  There is a good chart explaining the power usage of devices in the 2nd link.  Scroll down to the "inverters" topic for the chart.

About batteries and AH's.  The typical battery which comes with smaller RV's is usually about 70-90AH.  However if you discharge it more than 50% it really shortens the life of the battery.  If you have a pair of 80AH batteries for a total capacity of 160AH your available AH's are about 80.  If you have an electric cooktop that uses 1000 watts and you run it for 15 minutes to cook something you have used 250watts or a little over 20AH.  If you try to use a electric heater, typically they are 1500 watts and you run it for an hour (which is not very long when it is cold) you will have used 1500 watts which pulls 125AH (1500/12) from your battery.  That is way over your 80AH of usable capacity. 

The bottom line is if you are going to boondock, you need propane appliances and heaters.  A few people who boondock use elect fridges, but they size their battery pack to handle the power taken by the fridge. 

Drewd said:

I have solar and fair amount of battery capacity and can run any electrical except air conditioning.

Air conditioning powered by solar is a pipe dream unless you have above average means to install such a system.

Install the largest capacity solar sytem and battery bank you can install.  If you can fit 1000 watts and 800 to 1200 amp-hours of battery capacity, i'd go for it as that is what I think I owuld need as a minimum for a cloudy PNW.

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Did you intend to post to a thread that is over 2 years old?