I need about 150w of Solar Panel for a Goal Zero Yeti 400

[sammyman]

I currently have about 80w (four x 20w panels) in my cargo bin up front. They fit perfectly up there and never get in the way.

I’m finding 80w isn’t enough. I’d like to run an Engel 45 24x7 and not worry about running out power when on trips.

Do you have a recommendation to upgrade the solar panels to get 150w? Should I add on or should I just get new panels? What fits nicely up top? I have a roof rack if needed.[/b]

[Paulbeard]

This thread might be of interest. I expect you could get 400W of panel on the roof if you needed to.
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Currently -> Frida: 87 Tizian Red (mostly) Vanagon GL Westfalia w/ 2.0L ABA conversion
Formerly -> Steward of a 73 Super Beetle (Beater) and 67 Beetle 1300 (Little Max) both names by POs

[E1]

Suggest a portable panel Ugely, and charging batteries while you drive (Edit: meaning your alternator charging while bus is running).
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[jimf909]

This thread too. There are probably a half dozen helpful threads in search.

https://www.thesamba.com/vw/forum/viewtopic.php?p=6508096

Your capacity to run the fridge is s function of two things: solar gathering and battery storing.

How many ah of batteries do you have?
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- Jim

[dhaavers]

For the $450 it cost for the Yeti you could have 4x the capacity in batteries, tied into a battery isolator
for charging from your alternator & still use your panels for keeping it topped off while parked. I think
you're working on the wrong end of the equation..."add battery capacity, young man"...

- Dave
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86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS>

[shagginwagon83]

Alternator charging is my favorite charging method. However if you're in the same spot for days at a time, solar charging.

4x20w panels sounds annoying. Solarblvd has 12v panels for cheap right now. A 120w flexible for like $90. I have a 130w foldable panel with a 25' extension cord.
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Brandon
"Jo Ann" - '83.5 Westfalia EJ22e w/Peloquin
Instagram @joannthevan

[E1]

Hey Brandon, have I mentioned my concerns for your poptop duration?
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[shagginwagon83]

Nobody has ever mentioned it before. I'm a weekend warrior right now
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Brandon
"Jo Ann" - '83.5 Westfalia EJ22e w/Peloquin
Instagram @joannthevan

[E1]

Beast.

Sammyman, were you looking to add 150 watts, or another 70? We have a 120 portable and two 100aH AGMs, and it'd be more than enough for what you *think* you need. But we live in the west so part of the equation is where you are per how much clear sun you get. But more is waaaaay better than less as a general rule -- and quite dependent on whether you let the alternator help.

Just know this is hard on alternators, so we carry a spare (with a pulley mounted!) but in the big investment scheme they're cheap enough.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[jimf909]

[E1]

I know it's been posted here but bet a lot of people would love to see exactly how that "simple math" works.

Not ashamed to admit need of a refresher myself, especially in terms of practical use, i.e., a percentage to add to the total to have enough reliable power. Did that five years ago and had a decent margin but it wasn't enough in actual use every day.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[dobryan]

[Abscate]

The math

It’s easiest to work in units of energy, and Watt hours are most convenient units.

Anything rated in Amp hours, like a battery, is quickly converted to Watt hours by multiplying by 12 volts, the system voltage

That 33amp hour battery is thus a 33x12 = 396 Watt hour source.

You add up the loads, the things using electricity, by multiplying the watts they draw by th encumber of hours they are turned on.

Fridges have to be calculated by both the draw and the duty cycle but it turns out for a compressor fridge it will use about 1 amp hour per day per degree Celsius....so 25 amp hours on a mild summer day of 25C, 35=Amps on a hot desert day of 35C.

Finally, for solar panel, you take the number of rated- watts, multiply the number hours of sunlight, then divide that number by FOUR to get the real world estimate of solar watt hour capacity.
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.ssS!

[sammyman]

Hey guys,

Thank you for all the great information in response. I'm not willing to tie into my alternator. I need the fridge for the store, and occasional camping trip. I love that I don't need to worry about the hassles of tying into my battery and alternator.

I am willing to spend money on a bigger battery and more solar panels. I wonder if I can tie a Yeti to a marine battery somehow? Right now the yeti 400 fits perfectly under the rear fold down seat for easy access. Otherwise, I know two will tie together and I can put another under the drivers seat maybe? I know they are expensive for what they are, but they are convenient for me.

Yes, I'd like 150w total. I'll run the calculations today on my needs, but feeling confident that would keep me satisfied on trips. Thanks!

[Paulbeard]

[Abscate]

Just to throw this out, the 25 amp hour draw of a compressor fridge is a 300 watt hour draw , or 1/3 of a standard battery.

You will need 1200 watt hours of solar capacity to keep up, or about 400 watts solar for 12 hour days to stay in full charge condition running just the compressor fridge.
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.ssS!

[E1]

If everyone who needed to know your math answers on this bought you a beer, it'd likely become problematic in time.

Thanks for this, awesome.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[dhaavers]

x2...



- Dave
_________________
86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS>

[Abscate]

The two most overlooked things

1 you don’t want To cycle a battery below50%, routinely. It’s ok to do it on occasion but not during your camp cycle every day. Ergo, your 80 amp hour (960 watt hour) battery has a useful capacity of 40Amp hour ( 480 watt hour)

2 you plan on solar panels delivering 1/4 of their rating over the day. You lose 1/2 due to the trigonometry of orientation, and 1/2 due to bugs, dirt, toenail clippings that impede the panel. These effects are independent, so the loss is 1/2 x 1/2 = 1/4
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.ssS!

[shagginwagon83]