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how much solar?


Tex Bigfoot

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I deer hunt and so I have a smaller trailer that I pull to the campsite and park for about 6 weeks at a time. Rather than carry my 1350 watt generator back and forth I was wondering how large of a panel I would need to recharge and hold the charge in my battery . I hunt more or less the first week of season and then mostly weekends after that so it would have most of a week in full sun to recharge.

a few lights ( LED) and the water pump for showers is about the draw I would have.

I only have the one battery (750CCA deep cycle) but could add a second if needed.

 

A ball park guess is about what I need ,if the battery got low during my week I am ok with hooking up jumpers to charge if needed.

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Just LED's, water pump, and water heater use on demand (not running continuously).. no furnace or the like...

 

Simple answer: You could get by with a single 100watt panel (probably get by with less, but $ to watt.. the best deals will be in a single full panel). Deer season being the top side of winter you will be getting less sun. If you are like me, I don't shower every day while hunting, hit the rack shortly after supper, and gone all day so... 100watts should be able to keep up with your needs over a week. Certainly over just a weekend while it's been charging all week long.

 

It never hurts to have a second battery in there. Get a few overcast days and the extra juice on hand never hurts.

 

There is a long answer too, but I don't think that's what you're looking for.

 

I would say slap it on and go have some fun!

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While they would certainly not accept many amps because they are going to essentially be fully charged all week, without a controller they will be getting full panel voltage all day long. That's going to boil off water.

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I had the same set-up with my tent trailer. I used it for bird hunting in late October in eastern Washington. Normally sunny.

 

With the 30 watt panel is was touch and go. I did have TWO 1157 bulbs (not led) and a water pump for the sink and shower.

 

I got a 125 watt panel and stuck it on the bike racks on top of the tent trailer. No problem recharging the battery on a daily basis. I would get a charge controller. The panel will put out about 7.5 amps and can easily boil off a battery. Panels are cheap enough now that I would get the largest I could fit on the roof.

 

IF your in Texas you probably could get by with a smaller panel, but I would definitely get the charge controller. BTW.....there is no such thing as too big of a solar panel, since they generate so little power.

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Tex Bigfoot, a battery that is rated in CCA is not a deep cycle battery. At best it's a hybrid battery often labeled as a "Marine or RV" battery. It will not cycle as deeply for the number of cycles as true deep cycle battery which is designed to provide low current draws for long periods, not high current draws for short period (like a typical car starting battery.) I would recommend replacing your single battery with a pair of 6v golf cart type batteries (wired in series to 12v) when your current battery bites the dust - which will probably be in a couple years (at most) if it is new. This will typically give you about 225 amp/hrs. or about 1/2 this in usable amp hours as discharging much below this reduces your batteries life proportionally to the depth of charge remaining. This added capacity will make up for cloudy days when your solar is putting out little to no power.

 

Since solar panels are coming down in price I would recommend buying 200 watts, but no less that 100 watts for this battery bank and your needs. It's a funny thing. The more power you have, the more uses you'll find for it. Yes, you need a charge controller. I also recommend buying heavier wires that you think you need to minimize voltage loss. With this setup you could even add a small inverter, like I use to power my TV/DVD player or whatever small 110v ac appliance, drill, light saw, etc. you'd like to plug into it. Handy Bob has some great advice on building small solar systems. https://handybobsolar.wordpress.com/

 

Chip

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Thank you all, where we camp (Cow pasture) is in full sun most days . Yes it is in Texas so there is plenty of sun .Yes the water heater is just in the evening I turn heater on take shower and turn off until next day.

So I will be looking for the 100 watt panel and charge controller. I am hoping to set this up as a portable unit mainly so as to not drill holes in the roof but will just need to check the size and ease of doing so. Thanks for the thoughts on the two 6volts I will look into that .

 

Will NOT be adding a TV, that is one of the reasons I hunt just to unplug from the BS, Most of the time I don't even care if I kill, have just sat and watched deer all day without a thought of shooting.

 

Edit: wow now overwhelmed at the choses what are your thoughts on this kit? For $169.00

 

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Tex, when you do install that solar panel, use much heavier wires than the ones that come with the panel. They will have less resistance and provide more power to the charge controller resulting in a faster charge to the batteries. Use the same size heavy wire from the charge controller to the batteries as well.

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That's a pretty decent set up. I would shop around for similar kits like that. You can probably get some really great deals this time of year.

 

I hear ya.. some of those kit panels you can just toss into the sunlight in the winter months and do a fine job keeping your needs met.

 

I wouldn't invest in a pair of 6v's unless you are going to do more dry camping year round. For just a hunt camp I think you are pretty well situated.

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If considering a portable system you might want to look at this: http://sunelec.com/solar-panels/solar-laminate-136-watt.html

 

It is a 17lb, 136 watt solar flexible panel that you just roll-up and put away when done. Best part is it's only $76.16 (only 56 cents/watt!). It uses amorphous cells that work well in low light, partial shade and high heat. On the downside it is 18ft long when you roll it out (but only 15.5" wide). At 33v you will need an MPPT controller (which may cost more than this cheap panel http://www.amazon.com/Tracer-2210RN-Charge-Controller-Regulator/dp/B008KWPH12/ref=pd_sim_lg_7?ie=UTF8&refRID=1AFFD5T0YGW9HTPXZ51B), but this allows you to save money with lighter gauge wire than you would use for 12v system. A higher voltage system makes power earlier in the morning and later in the evening too.

 

Chip

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Edit: wow now overwhelmed at the choses what are your thoughts on this kit? For $169.00

 

 

 

That's a nice little setup, Tex. All the components you need to get you started. It's easy to get overwhelmed with solar. I would keep it down and dirty for what you are looking for. Bottom line.. you still have your genset as a back up anyway, right. You could go with a couple of 6v's, but that will double the cash outlay over that little kit you're looking at, and really not necessary for a couple LED lights and a shower.

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  • 1 month later...

As it turns out I did not get to order this when I thought I would . Ended up just now placing the order so it should be in next week .

 

Just in time to make one last ( well only for me this year due to my knee replacement) black powder hunt on the 16, 17 ,18th

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StarDreamers, larger wattage panels like you are looking at have more cells and thus are designed primarily for high voltage, grid tie applications. That said, Sun Electric has the best prices for higher wattage/higher voltage panels. You will need an MPPT controller to reduce the voltage and up the amperage for a 24v system. http://sunelec.com/?route=information/newsletter

 

Sun solar does have some larger 24v panels in the 300 watt range, but they are a little pricy. http://sunelec.com/solar-panels/24v-solar-panels

 

The sun 395 watt panel here puts out 82 volts, you can't beat the price at only 44 cents/watt sold as an individual panel! http://sunelec.com/sun-395-watt-monocrystalline-solar-panel.html

 

Chip

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Sun Electronics has some good deals. But they are not consistent in availability. If you can get the stuff, it is for sure worth considering. I've stopped using them because of issues like that, but there is nothing wrong with the products. Look at Wholesale Solar as well. And search around the Internet and you can find some good deals.

 

Racking the VERY large panels on an RV can be a problem.They can droop in the middle and subsequent vibration and shocks can affect the panels over time. So make sure you have a good mount if you are using the LARGE panels. The 45"x65" and thereabouts (more or less) is about the limit in my mind....but that is just a personal opinion and a generalization. Just be aware of the potential issues.

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Just my HO.. but I would really discourage using that large of a single panel in an RV application. I'm not saying that it isn't possible, but I have rarely seen a roof footprint where extruding appliances would not become a shading issue with something that large. $ to watt.. I can see where they can be very attractive, but no matter the $ to watt cost, it's no longer cost effective if you can only get 5% output.

 

Just sayin... There are a lot more high voltage panels out there with much smaller footprints that might dramatically improve overall system performance per $. Not even touching on the mounting issues.. :P

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We have 6 x 235 W panels which are about 38" x 60" (1 m x 1.6 m) and these work well on a 5th wheel. We have several in parallel and hee is room to walk the room between them. That 395 W is 4' wide and 7.7' long and I agree with Yarome that this size would be a footprint issue. Those that are 40" wide or less should not have much of a footprint problem on TTs, 5th wheel and motorhomes. We have a friend who now has 1800 W on his pickup/camper and toy hauler trailer (motorcycle).

Reed and Elaine

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starting to think about a solar system for our 5th wheel. We are planning to do some extended boondocking and reallly don't know much about what we really need. One thing I'm pretty sure I don't want is panels mounted on the roof if we can get away from that. Met a couple recently who had a solar suitcase and they raved about it, especially not having to worry about coach orientation. any advice would be appreciated.

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The first step is to decide how much power you need from your solar system, an energy audit is the best way to get that number. You need to check the DC power draw of every DC device you'll be using for any amount of time (not levelers or slides for example) while boondocking and get a real power draw number for the AC devices using something like a Kill-A-Watt meter that you can convert to a DC power draw number by factoring in the inverter losses.

 

You might want to think about saving energy at this point, swap incandescent lights for LEDs and possibly more efficient devices or putting things on switches to reduce power use. As examples many microwaves use 20 some watts to run the clock, sat receivers also run in the 20 watt range.

 

Once you know how much power you need think about how much power you'd like for things that are optional but nice to have. Design towards your like number for things like wiring, solar charger and inverter sizes and just buy the number of panels you need to make the "need number"

 

 

Portable panels are great and awful, how they work out for you varies by the level of effort you are willing to make and your luck. You'll need a safe storage spot for them as the panels are fragile and a sharp impact will ruin one. You'll need a solid outside mounting setup to prevent them from flipping and a bit of luck to avoid something getting tossed at them that will break them (neighbor with a weed-whacker comes to mind) as well.

 

Some of the portable kits will keep the lights on but not much more, the energy audit will keep you from getting an inadequate system so don't skip it and buy sunshine and unicorns from some fast talker, they are expensive and disappointing.

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Reed, I have 305's on my current coach - four of them. They are racked 2 together on a cross member that spans the coach side-to-side. That works well for these size panels. I could put on 2 more if needed but my 1220 watts is enough for now. I could put on the larger panels, but my coach is 45'.

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The first step is to decide how much power you need from your solar system, an energy audit is the best way to get that number . . .

 

Once you know how much power you need think about how much power you'd like for things that are optional but nice to have. Design towards your like number for things like wiring, solar charger and inverter sizes and just buy the number of panels you need to make the "need number"

 

To me, I'd take this energy audit "need number" as the minimum power required because your power needs will probably change (go up) + PV array derating factors (clouds, off-angle sun, etc).

 

My RV solar design philosophy is to pack the roof real estate with as many high-power panels as possible. You don't have to put up all the panels you plan for, just design (adequate wiring & controller) for it.

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My RV solar design philosophy is to pack the roof real estate with as many high-power panels as possible. You don't have to put up all the panels you plan for, just design (adequate wiring & controller) for it.

With the reduced cost of panels these days, on any but the "smallest"-needs system I recommend that as many panels as can fit on most roofs is what you will want. You cannot have too much power and the incremental cost of a few extra panels is not that much, relative to the entire job. There are exceptions, of course, but in general that is where I start , and then back off from there if needed.

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