Need some guidance on solar electronics brands

[Wits' End]

I am enjoying this forum, I'm not sure if this is the best place to post this. I'll ask my questions and then some TLDR, if you feel background would help.
We live in rural NE Minnesota, about an hour northeast of Duluth. Lake County, population ~10,000. Temperatures lately from -40°F-100°F[-40°C-38°C {233K-311K}].
I need about 4KWH system, totally off-grid, no likely-hood of future tie-in. I don't want to spend more money than I need to. However I want a good reliable system that will never fail , be expandable when needed, etc. etc. I've been thinking Victron or Outback. SMA seems a bit high $ for comparable specs. Schneider more grid oriented. That is my basic request for information. I have seen this-Best Brands of inverters & chargers. As well as lots of browsing around the forum, the internet in general, and 30years of electronics interest.

I would like a cohesive system. I am thinking separate components, but am open to discussion/argument for an all-in one. Concerns for field service.
I am thinking of two 3K or 4K systems either side by side, not really clear on the set-up of duplicate systems with one battery and one solar panel bank. I believe one 6kWH system would do us, again guidance please. Our plan is to have more battery than needed, fill-up with generator as needed.
We run with a 2KW genny now. Planning on adding a "normal small" refrigerator, maybe a chest freezer, thus the larger 'needed' load.
It seems like the electronics are most likely to fail, so extra money there is worthwhile. Spending money on Grid-Tie features seems like I should avoid, but most systems have that built in? Any that don't? I assume Inverter/Charger & Solar Charger. Unless Inverter, AC Charger, Solar Charger? Any other components? Maybe a 48V to 12V DC converter for some inverter downtime?

Solar Panels
I have a 6x12 foot [1.8 x 3.7 M] pole mounted homebrewed, welded, 2"[5CM] square tube, rack, that is a little oversized for 4 panels, I am thinking of 8 panels (2x4) or 9?(3x3) on angle iron, or aluminum [aluminium] solar brackets-Any thoughts?
Bi-Facial 400W+ as available panels--Any thoughts

Batteries
I was thinking of Big Battery 48V units, however, with the price of the Gyll 48V 5KWH packs I may go for 3 or 4 of those. Any thoughts?
Thoughts on just two stacks of Gyll batteries? No racking? or wood racking/shelves? I've mentioned elsewhere, concerns for warmth, mounting batteries above electronics, to harvest heat. Probably still some heat pads.

TLDR WARNING
My family has been off-grid for 25+ years.
We started charging a couple deep-cycle batteries in town, hauling 15 miles. Ever set a stainless pail on the 12V battery that was set by the door, for "a Minute"? ?
We graduated to a 100W panel and a deep cycle to run a radio/cd/cassette, and a ham radio.
Then a few years with golf cart batteries/2@350W panels to run radio/radio/laptop/a few lights/fans.
For the past 6+ years we've been running with a gas generator 2-2300 W. Generally getting 2 years of service, 7 days a week 4-8 hours a day.
As my wife and I hit 60 years old, each not combined, and we are down to 5 'children' at home, we are reorganizing the way we have been doing things. Thus the solid solar system. Maybe adding some propane heat, rather than all wood. The option of the "Double" system, 240V, for the possibility of a heat pump or AC for our "hot days". Please ask questions! Please give input!

 

[svetz]

I need about 4KWH system,

That's not much, I'm going to assume you mean a 4 kW array, if I'm wrong no biggie just adjust the math examples/thoughts. So for Duluth the insolation with panels optimized for winter would be:

Jan	Feb	Mar	Apr	May	Jun
2.63	3.82	4.31	4.45	4.42	4.34
Jul	Aug	Sep	Oct	Nov	Dec
4.59	4.50	3.98	3.36	2.66	2.27

or 9 to 18 kWh/d seasonally.

totally off-grid, no likely-hood of future tie-in. I don't want to spend more money than I need to. However I want a good reliable system that will never fail , be expandable when needed,... I would like a cohesive system....

Haven't priced it out, but there might be savings in a kit (saw AltE had a 4 kW array the other day). What's nice about that kit is it has the magnum inverter which I believe you can parallel to increase your capacity.

I am thinking separate components, but am open to discussion/argument for an all-in one. Concerns for field service.

Diagnosis is a pain, really like the per-panel diagnostics on my Enphase and I like I can get a hold of tech support when I need to.

I am thinking of two 3K or 4K systems either side by side, not really clear on the set-up of duplicate systems with one battery and one solar panel bank. I believe one 6kWH system would do us, again guidance please.

The "weak" point where things fail is the inverter, not the panels or batteries. So, not much reason to split the solar panels into two systems.

... I want a good reliable system that will never fail ...

If this is your #1 priority, then you should look at Enphase microinverters with Ensemble. It's what I have, but I'm on grid.

When every panel has a microinverter, there is no single point of failure. When a String inverter goes, you're completely without power until you can have a replacement shipped to you. When a microinverter fails, you're out one panel until a replacement is shipped to you.

The Enphase Ensemble solution will work off-grid, the only downsides is the battery is pricey (~$/Wh) and the generator support is still about a month or so away. It'll also work with the Tesla battery, they might have a better price point or generator integration story. Sadly, AFAIK, there's no DIY battery option with them (See Incrementally Adding AC Batteries for why). You'd probably have to have either battery indoors, no heating on them AFAIK.

Bi-Facial 400W+ as available panels--Any thoughts

Bi-facials need to be elevated off the ground a bit, increasing the albedo (paint the ground white or fill with white pea gravel) is a big plus. SAM can let you play with both.

Hope that helps! Sounds like quite the project, please let us know how it's going!

 

[Hedges]

SMA is expensive, but there are deals on eBay (and sometimes Craigslist) for both used and new old stock.
You might pay $2000 (more or less) for Sunny Island new in the box, and sometimes $500 for a Sunny Boy (typically used). A new fairly recent model Sunny Boy might be $1200.
I think microinverters that support frequency-watts would also work

Sunny Island is 6kW (5750W), 120V. You'll need a 120/240V transformer to use it with AC coupled (grid-tie) inverters.
It can also be used with DC coupled solar charge controllers, but AC coupled is often more economical, and is better integrated.

If you can get a deal on a DC solar trailer, than will be a turnkey system with 2500W of PV, Midnight SCC, two Sunny Island. It also has one or two FLA forklift batteries which may or may not be in good condition. Just park it on your lot for 11.5 kW 120/240VAC. Some sellers are asking $10k or so, better if you can get it for under $8k.

Here's a listing for $7800 (plus $1000 to ship from Las Vegas)

Mobile Solar trailer Generator 2350watt with 40KWH Battery OBO - $7,800 | eBay

Find many great new & used options and get the best deals for Mobile Solar trailer Generator 2350watt with 40KWH Battery OBO - $7,800 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Hedges]

Batteries:

LiFePO4 batteries pre-assembled like you're considering are expensive.
I use AGM, because just backup, not cycling every night, won't see more than a couple hundred cycles in 10 years.
DIY LiFePO4 with 280 Ah cells will cost a fraction of what my AGM cost, and should handle 80% DoD nightly for a decade.

FLA lead-acid (like comes with the DC Solar trailers), sized for 3 days autonomy without sun, would probably last 15 years (if not already neglected and damaged.) Most nights it would only cycle 15% DoD, but during cloudy days you would draw it down lower. So if you get one of those trailers, just use the existing batteries as long as they last.

My design (especially because it is grid-backup) has minimal battery and large PV array. In one day, PV can make 5x what battery will store. During power failures, my usage model is use-it-or-lose-it; I run A/C and laundry directly off PV power when it is produced, and battery is kept full. At the time I built it, batteries cost 10x as much per kWh as PV costs to produce the same power. Today, DIY LiFePO4 cost is similar to PV, so storage of power is more cost effective.

 

[Alphacarina]

Batteries:

LiFePO4 batteries pre-assembled like you're considering are expensive.

I agree, but assembling a pack using 280 AH lithium cells would be cheaper in the long than going with AGM's - Especially for a system that's going to charged and discharged every day like he's describing

If your calculations say you'll need 4KW, I would oversize things by 50% or so and shoot for 6KW - You only want to do this once and not have to be coming back later trying to add more

Don

 

[Hedges]

If your calculations say you'll need 4KW, I would oversize things by 50% or so and shoot for 6KW - You only want to do this once and not have to be coming back later trying to add more

Temperatures lately from -40°F-100°F[-40°C-38°C {233K-311K}].
I need about 4KWH system, totally off-grid, no likely-hood of future tie-in. I don't want to spend more money than I need to.

He did say 4kWH (4kWh?), not 4KW. If he really means 4 kilo-watt hours storage, that ain't much.
More reasonable would be 4 kW (peak) of PV, producing 20 kWh/day much of the year (but maybe only 8kWh/day in winter if he's lucky.)

40 kWh to 60 kWh of battery would be one way to weather multiple days without sun. Alternatively, 10 kWh or slightly less for one night's use, and fire up a generator if next morning is cloudy. The 10 kWh battery will cycle deeply every night, so the 3500 cycles available from LiFePO4 is needed. 40 kWh or larger means it rarely cycles deeply, so lead-acid (of the right quality) can last 10 or 15 years (but since DIY LiFePO4 can be had for same price or cheaper, worth considering.)

Deep freezing temperatures are an issue for charging lithium. One (rare and expensive) chemistry supports it, otherwise heating the battery will be necessary.
Lead-acid can handle it, but capacity is reduced while it is cold. Read threads by Trukinbear to see his experiences with FLA forklift batteries.

Powering A/C directly off PV is quite doable. As Alphacarina said, more is better. 6 kW PV rather than 4kW. Multiple orientations, so panels keep producing power more uniformly throughout the day, don't drain battery in the late afternoon.

 

[Hedges]

Oh, PV panels. Buy used. See what SanTan Solar has. prices $0.12 to $0.50/kW.

 

[Prefersdirt]

Another thought: Consider a small generator (do you have one now?). Something you can use to recharge the system should you go without sun for too many days. Spend a little extra and get one with electric start and runs on propane (plus gas). Electric start so you don't have to pull start it. Propane for allows for limited use with ease of fuel storage and no carb getting gummy from the gas.

 

[Wits' End]

I'll get some answers, here shortly

 

[MrM1]

FYI I would not see Schneider has more grid oriented. The sw and xw series are completely happy off grid or grid coupled for grid assist without grid-tied and grid sell back. And I found Schneider to be a great value for the money. My 4000 Watt SW will start just about anything.

 

[MichaelK]

My 4000 Watt SW will start just about anything.

Do you mean the Schneider Conext? Their 4024 and 4048 Conext models are the 4000W versions. The XW series are either 5500 or 6800W models. I actually have both, a 6848 and also a 4024, and I am very happy with both. I use the 6848 to power my cabin, and it runs the 240VAC well-pump superbly! I use the 4024 in the workshop which is my second stand-alone system.

Both have fully supplied the motor activated loads without complaint.

 

[MrM1]

Yes the Schneider Conext SW 4024. It will start my old tired 240v 1/2hp well pump... And the start up surge is over 40 amps on each leg. That would be an 80 amp start up total across the L1/L2. And that is above the start up spec for the 4024, but it has been doing so no problem for 3 years.

My next move is replace the pump as I think that start up is way too hi for a 1/2hp. But the bearings are bad, etc.