New System Build

[RoySalisbury]

First, a little background. I currently have an off-grid solar setup that I have been running for about 10 years. It consists of the following:

* Outback Power inverter (24v/3kw),
* 4 Outback charge controllers (due to differing strings and sizes),
* 6 - 210w, 6 - 320w and 12 - 330w panels.
* 16 - 6v/400a AGM batteries. (About 4 years old, usually ran to 75% DOD daily, never past 65% before generator kick in).

I'm now in a position that I need more power at night and to do that I need a larger bank. But these batteries are just too old to add more. And I would also like to go to a 48v system that can do 220v AC split phase.

So I have decided to build out an entirely new system and then either keep the existing hardware or sell it on ebay. The panels are good enough to move over to the new system (mostly).

So, that out of the way, I have been reading up on the latest solar systems that have came out and whats available. Also the battery tech is MUCH better than my AGM's. I plan on going for the LiFePO4 battery banks, but there are a few rack mounted systems that all "basically" provide the same thing.

Q: Are these rack mounted banks (EG4, SOC, etc) basically just using the same cells and BMS and are just selling a warranty of different kinds? Why would I choose one over the other? The price difference for 48v/5k bank is about the same for all of them.

Then comes the inverter. These seem to now come with charge controllers internal to them (vs the older Outback that I have). As stated, I'm looking to go for a 48v inverter this time and 240v split phase. My choices come down to the MPP LV6048 or the Growatt 6kw.

The MPP is stackable so I can expand it later and also has 2 separate charge controller inputs (2 different strings). This works great for my existing panels. But is limited to 145 voc input. Thats another issue I have with my current system. Voltage drop over the distance to the panels. The Growwatt has the higher VOC, but is limited to a single string and is not stackable. I'm leaning toward the LV6048.

The system that I have "so far" designed is as follows:

* Inverter - LV6048. Start with one, but plan to expand to 2 in the next year.
* Battery - EG4 48v/5k - Start with 4, expand to 8 within the next year.
* Solar - Keep existing 330w array (12 panels), and double that in the next year.

If I keep the other system running I may just run it on the 6 - 210w & 6 - 320w panels and use if for security lights and cameras. Perhaps use it as my "backup" power system.

And just for FYI, the current system is not used on a daily "living" basis and just powers the necessary items for an offgrid cabin that is only used on the weekends. In the next year or two I plan on using it on a a daily basis for normal living.

Roy

 

[Steve_S]

Offgrid Cabineer here.
AIO's (All In Ones) are Great but they have downsides, they use a lot of standby energy compared to component builds.
A System like you want with "Weekend Use" separate components work better as you can turn off everything but the Solar Charge Controller to keep the batteries topped up without wastage.
All, AIO's & Regular Inverter/Chargers all have their Overhead and that needs consideration as well. When living FT that overhead is just absorbed into the "operational cost" as it were, but it does still add up, some have discovered this the hard way.
Many AIO's can be stacked in series, yes, but so can standard Inverter/Chargers (of the proper tier & type), do not dismiss this point.

Your Outback SCC's are GOOD and can be configured to work well with LFP but I do believe that some of the older 1st generation are not quite compatible but I am not sure as I am not an Outback guy. I dunno if they still have a "Factory Refresh" option anymore, might be worth exploring that, it is good quality gear ! We have a LOT of Outback users here so it may be worth Posting a question about "I have Outback Model # and have question about Lithium Compatibility" or something like. I'm sure you'll get quick responses... psst there are a few OB experts here.... shhh...... You will need to provide, Make, Model, Version/revision etc as much info as possible is best.

Batteries:
You obviously know you can DIY them and we have all the info needed to do so, it really isn't hard BUT it is a test of patience and calmness LOL.
See this Resource I wrote up for one of our Known Good Vendors: Luyuan Tech Basic Lifepo4 Assembly Guide There is other info in there you will want to have on hand too.
Commercial Products are increasing Monthly and now every battery company (like previous solar lead only) has Lithium Based products and now almost all have transitioned to using LFP. Rolls Surette has Marvelous LFP Rack Mountables + but the cost is !EEKS! BUT they have always been "Rolls" and as such pretty premium to start with, but hey Awesome Quality so....
Have a LOOK Here and BE SEATED ! Lot of choices & much info. Not everything is available everywhere (Far less in the US than you'd think)
https://www.cleanenergyreviews.info/battery-storage-comparison-chart This lists all AC, DC coupled and Stand-alone as well. NOTE: It is updated every couple of months usually, things are changing fast.

! WORDS of CAUTION !
I started with Heavy Lead (Rolls Surette actually) and transitioned to 100% LFP, with a period where I had both LFP & FLA (Backup) on-line, now the FLA is offline. TAKE YOUR TIME ! While the terminology is all similar it is NOT IDENTICAL, the Lithium World changes a lot of stuff (for the better IMO) but it takes a steep learning curve to get a handle on the differences. IE: DOD is quite useless with Lithium, SOC is the only countable state of charge that works. It's a PITA because the differences are subtle but can result in confusion and getting incorrect info. It takes a while to Transition the thinking & terminology and you'll hit some frustration along the path. So If in doubt ASK the question, the only stupid question is the one not asked.

ALSO a HUGE Difference ! (Something that buggers up Old Lead Users) All Lithium Chemistries are Milliohm, Millivolt & Milliamp Sensitive and NOT Brute Force like FLA. We tend to talk in Cell Volts & Battery Volts as 3.350 Volts Per Cell or 53.600V for the pack of 16 cells. 2 or preferably 3 decimal place accuracy when possible, and that means furtling with teh equipment to get it right. Tolerances are pretty tight when you get into it.

Hope it helps, Good luck