2200 watts of solar on the roof?

jkam

nomadic man
I have a buddy with 1600 watts on his roof.
He uses six 115 AH AGM batteries and that seems to be enough for him.
It's not an expedition vehicle, Winnebago Tour 42' diesel pusher.
It is an all electric coach, no propane, has a residential fridge and an induction cooktop.
He does run his generator to use the A/C but not much else in the summer.
Needs the generator for a few hours in the winter to top off the batteries.
 

MTVR

Well-known member
9 Panasonic HIT N250 panels would give me 50 watts more (2,250 watts). Every other Panasonic HIT panel array puts out less power, won't fit, or both.
 

MTVR

Well-known member
I have a buddy with 1600 watts on his roof.
He uses six 115 AH AGM batteries and that seems to be enough for him.
It's not an expedition vehicle, Winnebago Tour 42' diesel pusher.
It is an all electric coach, no propane, has a residential fridge and an induction cooktop.
He does run his generator to use the A/C but not much else in the summer.
Needs the generator for a few hours in the winter to top off the batteries.

Our box will be much better insulated, have much less interior volume to cool, and have much more power to do it.
 

MTVR

Well-known member
One of the failings (but not Lithium) of FLA and AGM is the loooonnng (Bulk/Absorb/Float) charge cycle. A large solar array is advantageous to make sure the FLA/AGM batteries are brought into float (zero chemical reaction) at least twice a week.

Yeah, that's true.
 

MTVR

Well-known member
The goal of running an A/C or mini-split at least part time, is what's driving my desire to see how much power we can fit up there.

But we have no size-proportionate goal for storing electricity- we don't intend to run the A/C at night or when there's no sun. The battery bank would be little more than a common connection point between the solar panels and the A/C unit.
 

MTVR

Well-known member
So if I had 2,250 watts of solar panels up top to pass large amounts of electrons through to the air condioner during sunny conditions, and did not use the air conditoner when it's not sunny (to include not using it in the dark), how much lithium would I need? Would a single 100Ah Battleborn work? Two of them? Three? Four? At $1,000 a pop?
 

67cj5

Man On a Mission
So if I had 2,250 watts of solar panels up top to pass large amounts of electrons through to the air condioner during sunny conditions, and did not use the air conditoner when it's not sunny (to include not using it in the dark), how much lithium would I need? Would a single 100Ah Battleborn work? Two of them? Three? Four? At $1,000 a pop?
Well I'd say no because 2250w in a perfect world is going to make 175.78Amps @ 12.8v, If any thing I'd say you would have to cut the output stage of the Controller or it might beat up the battery, At a 33% charge rate you would need around 527.34 Ah of batteries or a bare minimum of around 351.56 Ah if they are totally flat, So I am thinking about 700Ah of batteries would be a good balance,

Much like that Trailer in the story at the top of the page, It can have up to 47.66Kw, That's enough to run a normal 4 bedroom house,
 

jkam

nomadic man
When it comes to running A/C. If you want to be comfortable and not worry about when you can use it, then a generator seems to be the best solution.
When my buddy did his system two years ago, he looked at lithium and decided that the price was still way too high to justify.
He figured that 4 lithium would be what he needed.
 

dreadlocks

Well-known member
You'd need 4 battleborn sized batteries in a 2s2p configuration for 200AH of 24V, that would dump about 86A @ 100% Solar input, which would be about ~0.4C, fastest you can charge em safely.. at that point id be building your own and saving money over a BB w/more flexibility and repairability.. DIY bank could probably get it down to same price as 6 lifeline agm's, but your looking at like 120lbs of LFP vs 500lbs of lead.. thats quite a bit of weight savings.

The bank would be rated for 200A out @ 24v thats 4800W of power you can get out of it.. you could could try to do less capacity but its one of those cry once buy once ordeals.. you treat your LFP cells well and the'll still have most their capacity in a decade or two.. if your full timing it and cycling through banks quickly that could alone be money saved in long run.
 
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dreadlocks

Well-known member
There are other panels than HIT, it 325W happened to be an ideal size for my roof.. do some research on high efficiency house panels, find the ones close to 20% or better and compare dimensions and layout.. less frames = more solar cells

100W panels are low voltage piddly antique tech, your going to have so much wiring and points of failures with 20x100W panels vs 7x300W panels.
 

MTVR

Well-known member
When it comes to running A/C. If you want to be comfortable and not worry about when you can use it, then a generator seems to be the best solution.

I never said anything about that kind of use.

Fulltiming with a generator means noise, exhaust fumes, maintenance, repairs, fuel costs, and having to find a place to put it, hopefully a place where it won't get stolen from.

Five years of daily fuel costs alone, are enough to push me towards solar.
 

67cj5

Man On a Mission
I never said anything about that kind of use.

Fulltiming with a generator means noise, exhaust fumes, maintenance, repairs, fuel costs, and having to find a place to put it, hopefully a place where it won't get stolen from.

Five years of daily fuel costs alone, are enough to push me towards solar.
I have a 2000w generator but that is only to rescue the batteries with the help of a 35A Charger for those times when the sun don't shine, I have 6 X 150w Panels but have yet to piece it all together, I'm thinking of running 2 sets of 3 in series/parallel so I end up with 450w X 2.
 

Alloy

Well-known member
I never said anything about that kind of use.

Fulltiming with a generator means noise, exhaust fumes, maintenance, repairs, fuel costs, and having to find a place to put it, hopefully a place where it won't get stolen from.

Five years of daily fuel costs alone, are enough to push me towards solar.

I've lost track of hours of quiet time (powering others so they didn't run generators) that I've thanked myself for by over sizing our solar......but ......running a generator (or truck engine) will be needed for AGM/FLA due to the fact that these batteries at less than 100% SOC will form sulfate crystals on the plates. Burning $5-$10 of fuel/week in winter will add years to lead acid battery life and keep the idle hours (oil changes) down on the truck engine. I bought a 2Kw Honda (our 3Kw Honda was too big) 3 1/2 years ago that has 84hrs ( https://tinytach.com/ ) on it now.
 

67cj5

Man On a Mission
I've lost track of hours of quiet time (powering others so they didn't run generators) that I've thanked myself for by over sizing our solar......but ......running a generator (or truck engine) will be needed for AGM/FLA due to the fact that these batteries at less than 100% SOC will form sulfate crystals on the plates. Burning $5-$10 of fuel/week in winter will add years to lead acid battery life and keep the idle hours (oil changes) down on the truck engine. I bought a 2Kw Honda (our 3Kw Honda was too big) 3 1/2 years ago that has 84hrs ( https://tinytach.com/ ) on it now.
You can stop the sulphate crystals from forming by Charging them with a good smart charger once a month or use a normal charger and let it get up to 15v for about an hour, That can boost the CCA, My 800cca batteries read over 900 CCA and they are almost 3 years old next month, (y)
 

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