24V w/Growatt

[monstaamilli]

Hey all,
So my fiance and I are putting a backup system in our airstream to ensure she can do her work off grid at all times while we travel for a week at a time.
I ordered a kill a watt meter figuring her 2 screens and WD15 and laptop, mouse, keyboard (THAT EFFICIENT?) would be pulling many more watts than i've measured over 27 hours of total time, 8 hours of it she was using her setup it only reads .49 kwh.
My personal laptop is between 40 and 60 watts as well as hers. I estimate 8 hours a day for each of these too.
We purchased the Growatt to build a 24V all in one system already which seems like overkill now that i have these measurements. We have yet to purchase any panels or a battery. I figure we can probably switch over to this system to power the whole airstream eventually, as i learn more and more.

Recommendations for panels and batteries?

Currently Have:
(1) 3kW Growatt All in one
(1) 75' 12 gauge AC extension cable (for input and output)
(1) 4 gauge wire kit for all in one to batteries
(1) 40' pair Solar panel to MPP wires

with those wattages and info what do you recommend for sizes of batteries for 8 hrs/day * 5 days/week?
wanted the 24v power wall but its out of stock. should i do (2) 12v or (1) 24v?
will that work with the growatt all in one?
How many W of panels should I maintain? and will i need more solar to mpp wires?

Thanks all!

 

[monstaamilli]

LiFEPO4 batteries are the best way to go too right?

 

[gnubie]

If you want to use the system for more than a few years yes. If not the economics may not stack up. If you are going mobile, space and weight come into play too as does the nature of charging. Lithium is far lighter, more compact and easier to charge than lead acid - both quicker and can live happily with partial charging.

When sizing the solar array you need to consider your wost sun exposure vs daily power demands. Under heavy clouding an array can go down to 10% of its paper ratings. Once you have a fair idea of your worst production period (which might be a week, or more, of bad days) you can think about array sizes and battery capacities vs loads.

You also need to think about vehicle sourced charging. With loads as low as you mentioned you could supplement or perhaps entirely charge your battery bank from your vehicle's existing DC system while driving. A couple of kWh is minor in the scheme of things when pushing a box on wheels through the air at 50mph. Obviously you'd need to take your final loading into consideration since you plan on running the whole show off this system eventually.

 

[monstaamilli]

I should also note that we purchased an inverter generator that runs off the LP tanks we already have so we have an alternate charge and power source for situations such as heavy cloud cover in the pacific northwest. We are traveling with an f350 and a 8k pound trailer so weight and space isnt really an issue for the two of us, yet.

Vehicle sourced charging as in alternator? or the cigarette lighter port?
After watching many of will's videos i feel like messing with that isn't something I wanna do.

If i were to put this setup in the backseat of the truck, would i be able to power run something from the growatt to the lighter port? it also has a AC 110V 400W max port that register 115V on the Kill A Watt meter. That seems like it would charge it well during our travels with the 12 gauge ac extension cord, yeah?