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UrbanElite, I added another paragraph to my previous comment.
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2.2kw Suntech mono, Classic 200, NEW Trace SW4024 -
Seconded on the advice to get the 40 amp charge controller.
I don't agree with this. It's not like his fridge pulls 40 amps. The OP says it pulls 65 watts (~5 amps), which is easy. My friend and neighbor has this fridge, which pulls the same 65 watts, and he powers it for weeks on end with his two crappy 12-volt panels totaling 240 watts going into two Trojan T105's:That being said 400 watts of solar panels isn't going to get you to 40 amps of charging power. If you are just going for weekend trips and the trailer can catch up during the week you may be alright. If after a couple 3 day weekend trips you find You're working your batteries too hard and not able to recover you will need more panel output. Personally , considering you are just in the building stages, I'd buy a couple inexpensive 60 cell 265 watt panels and a decent MPPT charge controller.
He doesn't pre-cool the fridge or anything in it. I've got an extra 300 watt panel, which I offered him, and he says he doesn't need it. And he has lights on literally all the time (he has blue LEDs that permanently shine under his trailer for effect) and plays his stereo with his obnoxioulsy loud subwoofer all the time. (And don't get me wrong, I have nothing against obnoxioulsy loud music, as long as I'm the one playing it...)
[Edited to add: I'm not suggesting that his specs are a model to shoot for, I think he's under powered, but it's an illustration of how easy it is to power an occasional 65 watt load from decent solar]
As far as these panels:
http://www.kijiji.ca/v-electronics/e...utm_source=sms
Those are the specs I use. I have two of them, flat mounted, feeding into a 40 amp, 100 volt charge controller:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I get about 450 watts of power from them when the sun is high on most days.
The problem is that those panels have an open circuit voltage (VOC) of 45 volts, and if you're running two of them in series that means you get 90 volts, which is close to the rated voltage of the charge controller. And some very knowledgable people on this forum have said that I might get a spike in the morning that exceeds the 100 volt rating of the charge controller. That of course begs the question of what exactly will happen: nothing? dead charge controller? or sparks? I'm in Northern California and haven't travelled to the desert yet, where a cold morning might provide that spike.
Anyway, you can avoid the issue by getting the 150 volt version of that charge controller:
https://www.amazon.com/SolarEpic-Cha.../dp/B00YCI48F4
It's not much more $$ anyway. Make sure to get the remote monitor box (it's on that page too), since that controller doesn't have any display.
Or, if you have the $$, get the Morningstar MPPT-45. I'ts more than twice the money when you include the display (at which point it's about triple the price), but it's probably a bit better, and is 150 volts. That said, lots of folks have done side by side comparisons and the output from the Morningstar and Tracer are pretty much identical. And I have nothing but praise for my Tracer, and I have yet to read a single bad review for it from anyone who's using it correctly. But if someone gave me a free trade-up to a Morningstar I'd take it!
And another possibility I should mention:
I use my RV for surfing, which means it has to carry surfboards on the roof. When I carry more than my usual quiver I have to cover part of one of my panels part time. When I do that, I switch over to parallel wiring of my panels, since otherwise covering one of the panels will kill all my power. I've compared the output between parallel and series and I'm getting the exact same power output from the panels. Granted I haven't compared it when the sun is lower, which is one of the traditional times that an MPPT charge controller will extract more power from higher voltage, but I don't get much power when the sun is low anyway. .And of course the panels are still 45 volts, which is still high enough for MPPT to do it's thing. And when they're mounted parallel I can fit 3 of those 300 watt panels without exceeding the specs of my controller. And I get those 300 watt panels for all of $150 if I get "last year's model", or $210 for the latest and greatest. Sure it's an unknown brand, but I compared them to a set of Canadian Solar panels and I was getting the same output per rated watt.
If you do go parallel though, you need to fuse your panels for safety. Put one fuse on each panel:
https://www.amazon.com/dp/B019YP0HQ8..._Y1oezbEV0ZKE0
And I use these joiners:
And one thing I should mention is that when you're going parallel you need thicker gauge wire, since the amps being carried by your wire is higher. So definitely get the 10 gauge wire, it's not much more expensive anyway:
https://www.amazon.com/Black-Gauge-S...ICM/ref=sr_1_4
Last edited by Wrybread; 05-29-2017, 03:12 PM.Comment
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I'm glad your friend doesn't need to do any of the things I've suggested but that's his choice. If he doesn't mind running his batteries down by unnecessarily doing something as simple as pre chilling his refer and beer. fine. The suggestions I've made are ,as far as I'm concerned, are sound and will insure his batteries don't get unnecessarily abused. There's many ways to approach solarizing an RV and I would prefer, and suggest, a method that doesn't ride the knife edge of having enough charging ability or not.
2.2kw Suntech mono, Classic 200, NEW Trace SW4024Comment
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And to figure out your wiring, if you don't know it already, you need to learn Ohm's Law: Watts = Volts * Amps (a good way to remember it is "West Virginia"). So if you have 2 300-watt @ 45 volt solar panels mounted in parallel, you have:
600 = 90 * Amps
600 / 90 = 6.6 amps
If those two 300 watt @ 45 volt panels are wired in parallel, you have:
600 = 45 * Amps
600 / 45 = 13.3 amps
Using the chart here:
You can see that 12 gauge wire is fine for that. However, if you increase that to 3 300-watt panels, you get:
900 watts = 45 volts * Amps
900 / 45 = 20 Amps
Now you need that 10 gauge wire.Last edited by Wrybread; 05-29-2017, 02:39 PM.Comment
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Me too, which is why I was offering him another panel. I'm not presenting his specs as a model, just to point out that powering a 65 watt load for a few hours a day is simple for a decent solar system. Hell, my system (600 watts of panels) puts out over 90 watts from the first meaningful rays of sun and puts out 450 watts most of the day, so powering that fridge even without batteries all day long is trivial. But interestingly he says he doesn't need the extra panel, and I've camped with him for weeks at a time and his fridge does just fine. And he's had those batteries for at least two years now.I'm glad your friend doesn't need to do any of the things I've suggested but that's his choice. If he doesn't mind running his batteries down by unnecessarily doing something as simple as pre chilling his refer and beer. fine. The suggestions I've made are ,as far as I'm concerned, are sound and will insure his batteries don't get unnecessarily abused. There's many ways to approach solarizing an RV and I would prefer, and suggest, a method that doesn't ride the knife edge of having enough charging ability or not.
And sure it's best to pre-cool stuff before camping, but obviously that's not always possible, nor is it necessary.
Me too.I would prefer, and suggest, a method that doesn't ride the knife edge of having enough charging ability or not.Last edited by Wrybread; 05-29-2017, 03:13 PM.Comment
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How are you coming up with 65 watts? 115 volts x 1 amp = 115 watts.
With 50% duty cycle at 65 watts x 12 hours = 780 watt hours
115 watts x 12 hours = 1380 watt hours.
There is no possible way for a 200 watt panel to power that fridge. Anyone who says it can just simply is plain silly and no clue what they are talking about.
MSEE, PEComment
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Urbanelite I hope someone elses chimes in because what wyrebread is telling you is pure fantasy. He knows very little about solar power. He is telling you what you want to hear, not what you need to know.MSEE, PEComment
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Like Ike I said before I'm new to all those, so really anything you guys are saying In fact checking and researching, he brings some good points up and has been more then happy to offer insight on my questions I'm asking, so each to their own I guess, but the more the better as it gets more opinions and ideas going.
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OK so where did the 115 VAC @ 1 Amp come from?
Reason I am asking is the numbers do not add up. Power or Watts = Voltage X Amps. 115 watts do not equal 65 watts. Here is the deal with Solar Off-Gird power, the most important factors you have to get right is to determine how many watt hours you require in a day. time of year use, location, and special conditions. Without that information you are guaranteed to fail.
Example lets take just your fridge. You said you wanted it to run 24 x 7?. About any fridge with normal use will run at a 50% duty cycle. Say on 15 minutes, off 15 minutes. So in a 24 hour day is 12 hours. So if it uses 65 watts x 12 hours = 780 watt hours. If it uses 115 watts x 12 hours = 1380 watt hours. If you calculate for 65 watts, but it really uses 115 watts, you have a serious problem. Your panel wattage to low, to small of a battery, and to small of a charge controller. It would only be about half the size required. Not only would it be the inconvenient, but an expensive mistake on top of that and likely destroy your battery before you realized something was wrong.
Some questions you need to ask and have answered is:
Maximum time in days you will be in the RV parked? If you say 3 days or less, then there is no real need for solar. Reason is even with solar you size the battery for 3 to 5 day reserve. All you would need is a decent AC charger at home of RV park with power hookups, and a Battery Isolator in the RV ( This part is invisible to Wrybread as he cannot read) to recharge the battery while you drive. Now if you park 4 or mare days you should consider a generator, cloudy spells happen and once the batteries fall below 50%, you had better get them charged up ASAP or you are going dark.
Will this be summer or year round use? That is needed because of panel wattage requirements. You design off-grid solar for worse case. If you calculate panel wattage for summer, but use it in winter, it will not work. Summer Sun Hours can bee 300% higher than winter. So if you designed for summer and came up with say 300 watts, would require 900 watts in winter.
Do you park in shade? Panels cannot tolerate any shade from sunrise to sunset. Even broken shade will shut down a panel. if shaded say morning to noon, you loose half your power.
These are all common sense considerations. So you need to plan things out, if you fail to plane is a plan to fail.
Good luck to you.Last edited by Sunking; 05-30-2017, 03:01 PM.MSEE, PEComment
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Background time:
Sunking, as he never stops reminding people, is a certified engineer (note his footer). However, he's like the guy who went to cooking school but can't cook a hotdog. And make no mistake, RV solar is to engineering school as making a hot dog is to cooking school, it's dead simple, and the process is pretty worked out, and you absolutely don't have to be an engineer to do it. To make matters worse he has an axe to grind against RV solar for whatever reason, to the point that he'd even make recommendations like this:
If solar were hard to install or expensive, he'd have a point. But the batteries are the expensive part, and since you'll have those even if you charged your batteries solely at home (ha!), you might as well spend the extra $450 or so for an awesome RV solar system (two 250 watt panels, the 40a MPPT charge controller, and the wiring), which is still cheaper than you can spend on a crappy bottom of the line solar system at Camping World.Maximum time in days you will be in the RV parked? If you say 3 days or less, then there is no real need for solar. Reason is even with solar you size the battery for 3 to 5 day reserve. All you would need is a decent AC charger at home of RV park with power hookups,
And to be clear I'm not recommending powering that fridge (whether it's 65 watts or 120 watts) from 200 watts of panels. My recommendation is and always has been to get two 250 or 300 watt panels, a 40 amp charge controller, and 4 Trojan T105s.
And I'm dubious about the fridge you have, I'd recommend something more efficient like this:
And a bit about my experience with RV solar since Sunking brought it up: over the last 20 years I've installed solar in all 6 of the RVs that I've had during that time, starting with crappy old 75 watt panels and PWM controllers back when that was all that was available, through the modern era where big panels are cheap and MPPT charge controllers are easy to afford. I'm a huge advocate of solar for RVs since I've seen how easy it can be made to work. And I don't consider myself an expert, but that just makes it an even bigger endorsement: if I can do it anyone can.
And I'm not here to tell anyone how to do anything, I'm here to give recommendations based on my experience and collaborate with people and learn. If someone disagrees with a specific recommendation I or anyone makes, it should addressed specifically, and hopefully through collaboration we all learn. Unfortunately when Sunking gets involved it turns into him hurling insults in every direction, and he overcomplicates things due to his inexperience with RV solar until the whole project fizzles and dies. Click his username and look at his recent posts to see any of the 5 or so other feuds he has going at any given time.Last edited by Wrybread; 05-30-2017, 03:38 AM.Comment
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I will further read through your reply later but I'm off to work so I'm going to quickly scan through your questions and answer them.
I'm just typing what is on the label on the fridge which is as is: RATED VOLTAGE 115V AC, RATED FREQUENCY 60 HZ, RATED CURRENT 1.0A, POWER INPUT 65 W,
We usually camp over the weekend to 4-day trips to 7-day trips. Reason I want to do solar is I do not want to have to plug into a battery charger at home, as well any power I use during camping I can make back with the solar to maintain my batteries, that why there is no worry about low batteries or running out of power. If I can go 3 days on batteries and catch a cloudy day here and there while camping ill have enough to make it through those days and then next sunny day will make that power back to charge back up the batteries.
I will just be using it for summer time camping use, no camping in -45 and snow in a cargo trailer for me! haha
I will be trying to park in the most open areas for that reason so i have good sunlight for my panels, we mostly camp in open areas or in the mountains away from the trees.Comment
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UPDATE:
I found a good deal on panels locally. I am going to return my panels i bought and buy these. They are 320 watt panels specs are: Postive power tolerance from 0-5w, snow load up to 5400Pa, wind load up to 2400 Pa, 320W, operating Voltage 37.1 V, current 8.63 A, open circuit voltage 45.08V, short circuit 9.10A,
This way i would have 640 Watt total in panels, minus what I lost I get.
Ive been looking everywhere for batteries, so far from research and recommendations on forums Wrybread is right on the Trojan 6V 225 AH, do you think i could get away with 2 of those for now and more towards 4 later?
Any one else have charge controllers they can recommend?
Thanks guys!Comment
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The Trojans are default choice for RV's as any golf cart battery is 6 volt 225 AH.
So if you buy two of them is a capacity of 12 volts x 225 AH = 2700 watt hours of which 1400 watt hours are useable. If the fridge uses 115 watts like the label says at 50% duty cycle, the fridge uses 1380 watt hours. That gives you one day run time on a pair of batteries. For an RV you cant get away with three day capacity and discharge down to 30% capacity or two days So just one set of Trojans falls short of the mark
To generate 1380 watt hours of usable power requires the panels to generate 2000 watt hours. On an RV the required panel wattage depends on conditions and time of year. At best you might get 3 may 4 sun hours in Summer. That would require 400 to 500 watts of solar panels.
Now here is the last catch the Trojan batteries must be charged with at least 18 amps and no more than 45 amps. In terms of panel wattage and charge controller works out to 230 watts minimum with a 20 amp controller and up to 600 watts with a 45 amp controller.
So what this is telling you is a pair of T-105's if the fridge uses 115 watts, is not large enough. One cloudy day and you are done. You would need four of them to give you 3 days run time, with 400 to 500 watts of panels just to run the fridge. If you run them three days without a recharge, means it takes two to three days to recharge fully.
Think of it like money in the bank with no credit or forgiveness. You open the account with $100. It cost you $25/day to live, and you make $25/day. Get sick for 3 days and you are pretty much bankrupt with no way to recover unless you quit eating for 3 days or in solar case you go dark. With a simple $50 Battery Isolator, you start the engine and idle for a couple of hours or go get supplies and you are good to go again. When you drive to the camp site your batteries are fully charged and topped of by the isolator. Then completely recharged when you drive home. It is insurance or a paddle and life jacket in a boat.
Do not mix old and new batteries. If you need 4 batteries, get them now. But you are not even ready to plan yet. You still have not determined how much energy you need in a day. That is the very first step. It determines everything you need. Just like a plane on a 1000 mile trip that burns 16 gallons per hour and cruises 150 mph. You had better figure out how much gas you need before you take off and have at least 45 minutes for emergency and unexpected wind.
As Sun Eagle is warning you, you had better now exactly how much power that fridge uses, plus anything else you want and plan for it. .MSEE, PEComment
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