Battery ?'s

Real root cellars are typically ~40F. Many run warmer like ~50F. Would be nice to know how cold your root cellar gets. Keep in mind the Lithium (LFP) are limited to above freezing charging and it is highly advised above 40F for ultimate longevity. However, LFP can be discharged below freezing and will self heat somewhat once they are discharging so that can be a moot point while you are visiting the camp.

For the low(ish) panel wattage of 1kW LFP is fine. No need to bring LFP's to full charge regularly like FLA. LFP can reside nicely at mid SOC for years. No need to equalize either.

For the extended unattended operation like you had last summer LFP would be better than FLA. If you can disconnect the batteries before you leave that works best for FLA and I'd say the LFP's too. The BMS in the LFP's will shut down saving your batteries. LFP's are much lower maintenance.

No problem with the Midnite Classic though it would be nice if they updated a couple things on it for LFP. No experience with the Trace.

I'd do LFP. I regularly use LFP in below freezing temps. Doesn't take much energy to self heat them if need be. Insulation is your friend.

Only consider LFP's with low temp shutdown built-in. Providing that after the fact can become convoluted.

Although the BMS is a great thing that allows some cell level control and reporting they can also become a thorn and a weak point of failure in your design. This is one of the reasons why you will hear so many folks praise the higher quality/cost LFP battery solutions like those that are offered for sale here on NAZ's website and other competent places. Places that choose what they offer carefully for good reason because they care about building safe long lasting systems and relationships.

One common theme you should listen to is this. The BMS should always be regarded as a safety and reporting device and should not be implemented in such a way in which it breaks your daily charge/discharge current directly. Your charge controller and inverter/charger should be capable of reliably performing those operations independently from the BMS. As a matter of fact, the most reliable BMS's do not "gate" the charge/discharge current at all. In the error event they simply send control signals to other devices like the charge controller, inverter/charger and/or contactors to actually throttle the current on/of. Sometimes you can't get away from the built-in BMS with built-in current control and that can be OK as long as you buy a quality BMS or battery/BMS solution and understand the risks.

Of course the BMS performs other functions like cell balancing, cycle counting, SOC and comms. One thing it does not provide directly is fire suppression. Oh, and be aware that the BMS (with current gating) is the component that is most likely to introduce actual flame in to the equation. This is why some manufacturers install multiple fire arrestors within the battery pack/module itself. This because the actual cells won't flame up unless physically punctured but the BMS can flame up and cause a chain reaction within the battery module.

With regard to your root cellar. From my experience they are pretty humid and condensing. Is yours? Choosing components that are suited to the wet environment is a thing. Galvanic corrosion and plating at the board level should be considered. Not sure if your Trace and Midnite reside down there too but with LFP your might be bringing electronic components in to that environment so a sealed or conformal coated solution would be required in a condensing high humidity environment. Not a biggie for FLA.

Hope this helps.

Sorry, not sure why I read a new 400W array instead of a new 1600W array. Must be my old brain again.

You started out only needing batteries. Now you are getting an entirely new system. Since you are fully opening up the coffers I would challenge this guy on the quality differences between what he offers versus what you already have. Names like Trace, Midnite (Classic) and Rolls Surrette (RIP) deserve that at the very least.

I would pause at a cheap MPPT charge controller but they are out there and many folks do use them with success. There are also many folks that reverse direction after the fact for names like Victron (<<these are great) Midnite and Schneider. There used to be cheapos out there with large coils, like Rouge made in North America, but now a days they seem to all be high-speed switching types. Not my favorite but I'm not everyone either. Done right they can be and are great....for a price.

Not sure why you would eliminate what you have but understand the desire. You can include some of that old stuff if you have the room. Can't really have too much panel, ya' know? I was most concerned with the old Trace...but the Classic? Never dawned on me. Until this June I used a "jurassic" Classic s/n 115. I still have it in reserve duty and intend to fit it to a second array.

I know one man's experience means naught but I operate over 5kW of panel on one Midnite Classic 150. If you get away from 12V and can do a 4S pack @24V with these panels it should be fine. Seeing as you a getting rid of the 12V Trace anyways.

But there is something to be said about "less is more", simplicity and asthetics too... Will stay tuned to see what you decide.

Good luck!

shokman said:

I did install a mini-split ac that would be nice to run off the panels. It is a 110v 12000 btu

I do. Might as well take advantage of the summer months even though my system wouldn't keep up with this in less sun in wintertime while still supporting my critical loads panel. Here's the consumption of my 900sq/ft home cooled to 68 degrees by one 12k 240v 13 year old Mitsubishi. The two higher consumption days were over 90F and sunny. This is just the mini-split obviously.

If you are doing it now with a genny this is much better.

Hey littleharbor2, make us jealous. How much array did you need to add to support those Devil's Spawn temperatures while enjoying the gloriously abundant sunshine at your place in Baja?

For reference, I'm in Central New England, USA with an awefully shaded lot starting in October.

1100W load says a lot. I rarely see more than a 250W load on mine except briefly on startup. I heat with mine in the winter too. Much bigger numbers then...

90+F water temp? I'd be sweating buckets in there and wouldn't even know it! lolol Sounds great though. Up here the ocean is usually a bit too chill but you get used to it.

We pull our small rv to Moab occasionally. It never ceases to amaze me just how much work we get done with one single tiny little 180W panel on the roof there.

Well, I was shocked just now. Not with voltage, with the current reading of my minisplit. It is pulling 14.6x amps @115 vac, 1660+ watts