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tbax46

Wichita Falls

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Posted: 12/14/19 02:16pm Link  |  Quote  |  Print  |  Notify Moderator

What size of solar panels are needed to keep battery charged for a few days of boondocking.


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Yosemite Sam1

Under the pines.

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Posted: 12/14/19 02:20pm Link  |  Quote  |  Print  |  Notify Moderator

Rule of thumb, 100w with the caveat you are not overdrawing more than your solar panel is charging.

naturist

Lynchburg, VA

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Posted: 12/14/19 02:35pm Link  |  Quote  |  Print  |  Notify Moderator

Solar wattage needed depends on how many watt hours you burn and is a function of how many amp hours of battery you have. So it’s inappropriate to give a simple number. But I can give you some guidance based upon some assumptions, which you will have to fine tune yourself.

If you just have a single 80 amp hour battery as most TTs come off the lot with, AND that serves you well for a day, AND You use no more than the 40 amp hours recommended overnight, then a single 100 watt solar panel will suffice, PROVIDED You get a full day of bright sunshine, and use an MPPT charge controller.

To keep that battery fully charged on a cloudy day, you might want two 100 watt panels. If you have a pair of those same batteries, you will probably want 3 - 100 watt panels. If you have a Class A motorhome with a battery bank that runs to 600 amp hours, and you use them to capacity, think something like 600 to 800 watts of solar.

I would suggest that such estimates are very much dependent on how much power you use. So my suggestions above are highly dependent on your usage as well as my assumptions.





Boon Docker

Mountain Foothills of Southern Alberta

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Posted: 12/14/19 02:44pm Link  |  Quote  |  Print  |  Notify Moderator

I have 200 watts of solar with an MPPT controller feeding a 225 AH battery bank (two GC-2 6v batteries).
I boondock for weeks at a time and the batteries are fully charged by early afternoon as long as it is not cloudy.

Lwiddis

Mono Basin National Forest Scenic Area

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Posted: 12/14/19 03:35pm Link  |  Quote  |  Print  |  Notify Moderator

Do an energy use survey...actual or what you’d like to use. Your choice. That determines the battery amp hours needed, which determines the solar watts you need to recharge and the controller size. If you guess, you will be either undercharged or overpaying.

“battery charged for a few days of boondocking” is absolutely wrong. A properly sized solar system recharges fully almost every day. Limping along...for a few days? Solar isn’t a new toy or experimental.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watts solar-parallel & MPPT, Trojan T-125s. TALL pole for flags. Prefer USFS, COE, BLM, NPS, TVA, USF&WS, state & county camps. Bicyclist! 14 year Army vet - 11B40 then 11A - (MOS 1542 & 1560)


Trackrig

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Posted: 12/14/19 04:11pm Link  |  Quote  |  Print  |  Notify Moderator

It depends on so many variables:
Where you camp - cloudy winter northwest to sunny Arizona
What time of year - is the sun up high or way down on the horizon
How much TV do you watch, how much music time
Are you going to use the microwave to heat a cup of coffee on batteries
Do you like lots of lights on at night
Do you run the ceiling fans
Is it cool out and the furnace blower is working, two furnaces?
Lots and lots of variables.

An extra couple of panels costs very little overall. The big part of solar is figuring how you're going to install it, where to put the monitors and run the wiring. A little bit larger controller for three or four panels is almost nothing. If your going to go through the exercise, take an extra couple of hours and install three our four panels. (Solar is like horsepower, you never have too much and solar is cheaper than horsepower.)

Bill


Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.


theoldwizard1

SE MI

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Posted: 12/14/19 06:25pm Link  |  Quote  |  Print  |  Notify Moderator

Trackrig wrote:

It depends on so many variables:
.
.
.
Solar is like horsepower, you never have too much and solar is cheaper than horsepower.

I'll have to remember that last line !

Boon Docker wrote:

I have 200 watts of solar with an MPPT controller feeding a 225 AH battery bank (two GC-2 6v batteries).
I boondock for weeks at a time and the batteries are fully charged by early afternoon as long as it is not cloudy.

I would consider this setup and absolute MINIMUM !

BFL13

Victoria, BC

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Posted: 12/14/19 06:53pm Link  |  Quote  |  Print  |  Notify Moderator

deleted--got that wrong.

* This post was edited 12/15/19 07:25am by BFL13 *


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time2roll

Southern California

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Posted: 12/14/19 06:56pm Link  |  Quote  |  Print  |  Notify Moderator

How long is a rope?

Otherwise most people with two batteries get on pretty good with 200 to 400 watts. More is always OK. If you are a real miser 100 watts might work.


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tbax46

Wichita Falls

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Posted: 12/14/19 08:45pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

tbax46 wrote:

What size of solar panels are needed to keep battery charged for a few days of boondocking.


How can anybody have been a member since 2004 and ask a question like that????? Got to be a troll. [emoticon]


I can’t believe you would make an assumption like this. I don’t frequent the forums very often. I haven’t lived off the grid before and was simply seeking information. Luckily for me most of the replies were from helpful individuals.

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