How much solar do I need?

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Headache

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Spaceman Spiff said:
Valve Regulated Lead Acid batteries (Gel and Absorbent Glass Matt) have a pressure valve (usually 1 or 2 PSI) that will release hydrogen and oxygen if excessive pressure builds up inside a cell.

Which is almost always caused by overcharging and that can be easily avoided.  I was vague in my post.  I should have said that they won't vent if properly monitored.  That's why they can be installed on their sides as long as the person doing so takes responsibility for doing it this way. I'm not that courageous!
 

Headache

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akrvbob said:
$600, $500, $1000, $100 (or more)

Thanks for that estimated price break down.  I was kind of figuring a budget of about $2000 for electrical so this puts it near my ballpark regarding what I was willing to spend on it.  I'll have to rough it in Ehrenburg a few months before I can afford to purchase everything.  If the savings are that significant I'll certainly make the drive to Flagstaff.

I just have to figure out a good spot for those batteries! Are yours in the trailer? I've never seen a walk through of your set up.
 

fairymuse

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Remember that the solar panels are not the only part of the system, and the efficiency of the panels is not the only part of efficiency of a system. You also need to think about the inverter, the orientation and tilt angle of the panels, the wiring, and any possible shading that might happen as a result of nearby trees. Different solar panels offered on the website of Solar Panels Company have different rated efficiencies, so you don’t need to calculate the efficiency of the panels themselves. If the efficiency is lower, if means that the panel can not use as much sunlight. In effect, the biggest difference with regard to the efficiency of a solar panel is the amount of space that it takes on your roof. Less efficient panels need more space.
 

jimindenver

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The difference in bright sunlight between the least efficient and the most is little. What a panel does in cloudy conditions can make or break your system.
 

jonsun

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Sorry if this has been covered....

One big make or break is getting the manufacturer voltage into the battery right. This requires a good charge controller and physical measurements, don't just trust the screen. Some need more or less than the 14.4v.

If you plan to park in the shade in the summer, and why wouldn't you, think about having most panels in a mobile configuration to set in the sun.

And this has been beat to death and contentious but I run 17.9v panels over 30-50ft of 10awg cable into the sun and use a generator for boost, so I do not use mppt controllers as there's nothing for them to convert...But a good controller I highly recommend. Do not skimp on that. (I use TriStar 45)
 

jonsun

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bardo said:
Sorry if this has been covered....

One big make or break is getting the manufacturer voltage into the battery right. This requires a good charge controller and physical measurements, don't just trust the screen. Some need more or less than the 14.4v.

If you plan to park in the shade in the summer, and why wouldn't you, think about having most panels in a mobile configuration to set in the sun.

And this has been beat to death and contentious but I run 17.9v panels over 30-50ft of 10awg cable into the sun and use a generator for boost, so I do not use mppt controllers as there's nothing for them to convert...But a good controller either way I highly recommend from experience. Do not skimp on that. (I use TriStar 45 with accessories)
 

iaintnopornstar

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I'm looking to run a small refrigerator(grocery shop every other day deal), 40 inch tv, playstation 4, charging a laptop, led lights with a dimmer switch, some fans or maybe a small ac (depending on how energy efficient it is), microwave, hotplate. Don't think I am missing anything.

How much solar watts would I need? 

Can someone explain what an inverter does? Would I need one for what I am doing?

How does solar charging work and how long does it last?
 

wagoneer

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Stay at home, JUST KIDDING. Yah you will need more than can fit on a van unless you can 12 volt everything it's looking like you will need a large inverter (it changes 12 volt DC to 110 AC) why are you iaintnopornstar? I worked on the music as a musician on a lot of x rated movies with the Mitchell Brothers and hung out with the actors in North Beach, regular people
I am WAGONER because i have always had a station wagon.
 

Fluffhead

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From what I've read, a 1:1 ratio of battery capacity to solar panel is ideal. I plan on having 3 100W Renogy panels on my roof. Would I be better served having those 3 panels feed 2 (6V) batteries with a capacity of 210aH or 4 (6V) batteries with a capacity of 420aH?

Dometic 50qt fridge, fan-tastic fan, 12v lighting, 12v water pump, & charging of laptop and other devices is what the batteries will be powering.
 

jonsun

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iaintnopornstar said:
I'm looking to run a small refrigerator(grocery shop every other day deal), 40 inch tv, playstation 4, charging a laptop, led lights with a dimmer switch, some fans or maybe a small ac (depending on how energy efficient it is), microwave, hotplate. Don't think I am missing anything.

How much solar watts would I need? 

Can someone explain what an inverter does? Would I need one for what I am doing?

How does solar charging work and how long does it last?

150w if you run a generator for the AC
 

highdesertranger

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the 1:1 is the minimum. more is always better. Fluff sounds like 2 6v would work fine, however during extended cloudy weather you would need to be careful. highdesertranger
 

Fluffhead

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highdesertranger said:
the 1:1 is the minimum.  more is always better.  Fluff sounds like 2 6v would work fine,  however during extended cloudy weather you would need to be careful.  highdesertranger

Hmmm. Perhaps to err on the side of caution I'll put 4 batteries in.
 

SternWake

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Fluffhead said:
Hmmm. Perhaps to err on the side of caution I'll put 4 batteries in.

I'd err on the side of more solar instead.  

Extra battery capacity yields warm and fuzzies for the just in case factor, but extra battery capacity can also be that much more battery to prematurely sulfate and lose capacity if it does not get to and spend enough time at absorption voltage each day.  The time it ideally needs to stay at absorption voltage depends on many factors and is always different.  Less than Ideal is acceptable when one is not seeking ultimate battery longevity.
  Each pair of 6v batteries is another 125 to 140 LBs one must carry around.

Fluffhead, I power much the same items as you list, and have 198 watts of solar and only 90AH of battery capacity.  It is more than enough from march to october and unless I cut way back on laptop use, not quite enough over the winter.  This is in a pretty sunny environment and I do have optimized alternator and grid powered charging available to quench a hard worked battery.

My opinion is people tend to have too much battery capacity and too little solar for it.  Those who employ other charging sources regularly, and preferably early morning, or who only lightly discharge the batteries can get away with it, but the person draining their batteries to the 50% range regularly would do much better with a 2 watts to 1Ah ratio, or even 3 to 1.

More solar than required simply means happier batteries.

4 6v batteries might be needed to power large loads like a microwave on a big inverter.

More opinion, but I would prefer to tailor battery capacity depending on how much solar wattage one is going to have.  If you can fit 300 watts, I would get one pair of 6v GC-2 batteries for it, not 2 pair.

Any solar is better than no solar, but too much battery capacity can be a waste of money except in those rare times when one deals with a LOT of clouds for many days on end, and is sitting inside streaming videos all day and night long.
 

Gary68

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my take

how much solar do you need? none
besides a couple instances you dont need solar or electricity to survive

back when i was a little hippy kid living off grid all we had was a car battery hooked to a 13" b/w tv at night,lived perfectly fine

solar/electricity is a luxury
i put it at the bottom of the list with brakes,tires and such at the top
 

breeze

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If you base estimates off of probabilities of each event happening, like over 30 events, you will get uncanny accuracy well above 95% confidence by just assigning the probabilities of each event happening alone (no matter if your individual estimates are all wrong.)  So everyone's diligent estimates should be sufficiently close to each other, statistically speaking.

Solar is new sustainable technology that is now affordable. I am hoping Bob has his prototype solar standby AC installed and tested soon. If I don't have room to make it happen when he does, it will only be a brief time until I do make it happen in a high roof van.

China's pollution has already destroyed the North Pole, and also destroyed a significant portion of the South Pole too. Earth is on the pendulum swing toward ozone depletion, rising temperatures (on the average), and rising sea levels. Do I want AC? Hell yeah, waking up with crotch rot is no bowl of cherries.

Go Bob GO! Please deliver us from the Power Grid.   :cool:
 

Vanlifedreamer

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Hello guys I'm very new to van dwelling and I'm trying to gather as much information as I possibly can. I know for sure I want solar power but I'm not sure how much I need for my needs. Right now I'm estimating I need to power a fridge, a vitamix blender, charging electronics(phone, laptop, camera), a fan or heater possibly. I have been to the renology website and don't know which kit to get or inverters or battery?
 

sephson

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Hi Vanlifedreamer!

I'm in the process of adding solar to my road tripper. I don't have a lot of power needs, but I've opted to put as much solar as I could fit on my roof. I'm operating under the theory that there's no such thing as having too much power available. In my case a 200 watt Renogy system with a PWM charge controller ended up being the best fit both for the space available and my budget. I'd rather have an MPPT charge controller, but cannot afford one at this point in time. I can always upgrade later though. This will be coupled with a 225 AH 12 volt deep cycle battery that I got for free from my employer because they no longer need it. I would really prefer to go with a pair of 6 volt batteries, but I simply don't have the room, plus free covers a lot of flaws. For the time being I'm going with an Aims Power 300 watt Pure Sine wave inverter because I was able to get it for a price that fit within my budget. Again, I can always upgrade later if it proves to be inadequate or unreliable.

I think a good first step for you would be to measure the amount of space you have available, then find the panels that will best fit in that space. From there you can always trim back the project to better reflect your budget.
 

GotSmart

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Vanlifedreamer said:
Hello guys I'm very new to van dwelling and I'm trying to gather as much information as I possibly can. I know for sure I want solar power but I'm not sure how much I need for my needs. Right now I'm estimating I need to power a fridge, a vitamix blender, charging electronics(phone, laptop, camera), a fan or heater possibly. I have been to the renology website and don't know which kit to get or inverters or battery?
First.  The electric heater is out.  That will kill a battery bank in no time.  Most use propane.

Second.  The blender is a power hog.  You will need a large inverter to handle that.

Third.  Fridge.  With a good 12 volt unit you can get away with 100w to run it.  This is assuming you stay in the southwest.  To be safe go with more than that.  A week of clouds will not be kind to solar.  

100w will run the rest.

I have 200w of Renogy panels, and over 400 AH of batteries. (I found an exceptional deal) no fridge yet but I never go under 13v on my batteries.
 

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