Sorry about that, Unit meaning inverter charger. most are set via dip switches (you need manual
) and some of the better ones offer the ability to be programed via laptop for super fine adjustments or for strange one off setups.
all of the newer Sunny Island are High frequency are they not... pending the ability to get a used older model which are Low frequency... with once again no warranty... warranty rules for the beginner in off grid as mistakes will be made.
Ok so the Island are LF and the sunny boys are HF? then the LF model should take care of him then if he can find one in his price range. I just hate watching folks trying to use a HF inverter where they should be using a LF and then hearing of their loss when the magic smoke escapes the (attach name of any of the cheaper HF inverters).
Not sure the idea of explosive toxic gasses (when the batteries vent) drifting up through the floorboards and into the house is a great idea.TLDR: inverter OK (with caveats), batteries first timer go with AGM or LiFePo4 might or might not need heating pad depending upon battery type and location of battery box. Solar: 900 watts will be too small period. 1800 watts may or may not keep you happy. Your genset is probably 240 split phase, not 3 phase, most 3 phase is 208 from leg to neutral or leg to leg, split phase is 120 leg to neutral and 240 leg to leg.
first time working with batteries here are some issues you will run into.
flooded lead acid: if you do not have you charging parameters correct you will destroy them in a couple of months, so if this is a remote cabin that you only go to occasionally better off to start with AGM. (I have no experience with gel so no comments about them.)
as long as you can place them somewhere where it stays above freezing and your solar controller can be set to the batteries parameters expect 3-5 years use per set. I know some folks that tell of 10 years on them, heck I got 9 good years and limped on the 10th in my camper, but at my cabin I only got 3 and some change, and that was with experience from the camper.
when you jump up to a large AGM battery pack that is cycled daily getting them truly fully charged daily is difficult as they need a long absorb time= large PV solar array.
speaking of temps, if you have room under the house (sub basement or what not) then that's the perfect place for your batteries as a couple of feet below grade and the temperature really levels out. if not be prepared to make a box that is heavily insulated to trap heat in the winter. do that and you might not even need heating pads of any sort. I built a insulated power shed that held batteries, solar controllers and inverter and it rarely got below 4 or 5° C (40°F) even when it was -15°C (5°F) outside. biggest problem was I made it too large, if I had halved the size it would have stayed even warmer.
If you feel like experimenting a little bit LiFePo4 is the way to go at the moment when you balance out long term cost, longevity (cycle life) and power output. They will however need a heater pad and an insulated box as they are so efficient that they do not self heat at all. (plenty of plans, diagrams and mad scientist dreams floating on this here forum, so plenty of info, just need to do some sifting with the search button to find it.
inverter will work fine with these conditions:
Must have....a detailed installation manual that covers all adjustable settings? (need this to fine adjust battery charging portions).
Will 3500 watts be sufficient? (if free then this is a moot point you can live with a lot of things if its free. )
you will need more panels regardless. right now at this moment I am sitting at 3600' elevation it is early summer and we have cloud cover. with 4000 watts of PV currently installed (waiting to install next 4K of PV) It is an overcast day and I am getting about 20 amps of charge which is not quiet enough to offset what my split pack a/c, small chest freezer and small fridge are using. when the overcast is not here I see up to 50 amps of charge at the 54.4 setpoint for my lithiums. when its overcast like it is today...well you get what you get.
Regards, and best of luck!
Ken
sorry I specified that for Old_Skewler, as a novitiate to batteries I was suggesting AGM's. FLA are just too much for a beginner who is not there every day to mother hen the batteries. most guys who get 8-10 years from a FLA bank are on their second, or third bank and have learned the tricks. most beginners kill their FLA bank really quickly due to watering, equalizing, blah blah blah. so I suggested AGM's if he did not want to go lithium.
Can AGMs be kept in habitable spaces?
yeah, they don't off gas, and they are safer on their sides than lithiums at the moment. Hell they were the "Lithiums" of their age. They were designed for jet aircraft where you have a shit ton of vibration, and when doing maneuvers you cannot have acid spilling or off-gassing.
well we are almost a cult you know... we worship a sun god and dance around doing weird incantations when we anger or displease the battery, wiring or sun gods.... so I feel that my 10 dollar word for a 25 cent conversation is well fitted. Just because I have dyslexia and joined the Marine Corps does not mean I was not educated properly.
(joke)I disagree with that statement. While the off-gassing may not be as extreme as with FLA, it still happens. A quick google will show you. on their side? I agree much safer than LFE, but I'm also not suggesting that LFE be lain on their sides ?.
You are technically correct, but off gassing with AGM's only happens when you overcharge them hard. while it is not impossible, it would be the equivalent of one off-gassing event as once they off gas one time, they are done. Without googling, I know for a fact they were originally designed and used where the ability to be used in all positions and with no leakage or off-gassing while undamaged was a required trait. It was a military contract that paid for the AGM to be brought out of some chemists brain cells, onto a drawing board and into production. military tech and the industrail war machine has produced all kinds of cool offshoot tech.
Here's what made me disagree:
rvnerds.com
no worries we all have different experience/knowledge levels, that's whats' great about a forum we can share. FWIW in the early 90's while I was in the Corps, they still had some helicopters and aircraft that still had NiCd batteries and the wing were in the process of swapping them out to AGM's. It turns out that what we generally call AGM's these days were developed from sealed lead acid batteries and the current form was an offshoot development for the freaking Brit air force for AV8B Harriers and our air force waited until the late 80's to swap. The Marine Corps being the bastard children used up all of the NiCd stocks till the early 90's and then swapped out as available. I was combat logistics and we pilfered anything and everything while on deployment. we were using some of the "damaged stock" that came about to power boom boxs on field ops during the first gulf war....Don't ask how...we were shore party...and "there's no party like a shore party"
So how long after signing did your discover you checked the “marines” box instead of “air force?”
Thats Funny
Honestly I never knew I was dyslexic until after I had worked as a civilian for the DOD for about 10 years. they did not even have tests for it back when I joined the Corps. I managed HS with a b- on average, and always had problems transposing certain letters, numbers and words. 
