Solar Panel recommendations please

[Hedges]

I think we are beyond the OP’s backup battery for a CPAP scenario!

I think his 1500W of PV and 2400Wh of battery is too.
As you said, sufficient to power a window A/C.

Under-paneling (use only one panel and 12V battery) would be the simplest way to avoid/minimize excessive charge current for battery (but could still happen.) With some care put into system design it should power the essentials of his house while the sun shines, and things like the CPAP at night.

 

[Mark_B]

I think his 1500W of PV and 2400Wh of battery is too.
As you said, sufficient to power a window A/C.

Under-paneling (use only one panel and 12V battery) would be the simplest way to avoid/minimize excessive charge current for battery (but could still happen.) With some care put into system design it should power the essentials of his house while the sun shines, and things like the CPAP at night.

It may be way beyond my OP, but it is all fascinating to me. I appreciate you guys batting it around.
I've often wandered how I might power more stuff during the day (computers, lights, TV/Surround System, etc) while the sun shines, but still charge the battery for minimal night stuff.
Is there a post I might read, or some ideas you can give me for that kind of scenario? Those panels were so cheap I wouldn't mind buying a couple more if it made sense.
You've given me some ideas to chew on, but I am so new to this I'll have to do a lot of research to get a real rubber meeting the road understanding of what you've all said.
Anyway, thank you both!

 

[Mark_B]

Just for kicks, what is the max number of panels the 150/60 might handle?
Should I be looking at something else if I want to add a couple more 385watt panels?
Do you recommend something other than Victron?
They seemed like a pretty solid manufacturer, but I'm open.
If they list more of the prismatics I bought I might even double the battery too.

I should also say that I am very interested in enhancing the life of my batteries as much as is reasonably possible without being overboard about it.

 

[MisterSandals]

If they list more of the prismatics I bought I might even double the battery too.

With those panels and a 150/60, the batteries are the limiting bit of your system.
The batteries will only accept so much current, less than the 60 amps the 150/60 can supply.
At 60 amps, that is 60 x 12.8v = 768w of panels. So you have double the panels the 150/60 can supply at 12v.
At 24v it could supply 1536w (roughly the size of your array).

Trying not to get too far ahead of ourselves, do you have an inverter to power your CPAP?
That will likely need to be a pure sine wave and be sized by watts for the CPAP.
And, it has to be for either a 12v or 24v battery. So your battery voltage decision will affect which inverter you need.

 

[Mark_B]

With those panels and a 150/60, the batteries are the limiting bit of your system.
The batteries will only accept so much current, less than the 60 amps the 150/60 can supply.
At 60 amps, that is 60 x 12.8v = 768w of panels. So you have double the panels the 150/60 can supply at 12v.
At 24v it could supply 1536w (roughly the size of your array).

Trying not to get too far ahead of ourselves, do you have an inverter to power your CPAP?
That will likely need to be a pure sine wave and be sized by watts for the CPAP.
And, it has to be for either a 12v or 24v battery. So your battery voltage decision will affect which inverter you need.

I've been holding off on the inverter purchase so that I don't buy something underpowered for the system I am building.
Honestly, it's been a struggle with my better half to portion out the funds, but she is getting used to the idea.
So that is why I started small, but appear to be getting bigger on the system as time goes on.

 

[Mark_B]

With those panels and a 150/60, the batteries are the limiting bit of your system.
The batteries will only accept so much current, less than the 60 amps the 150/60 can supply.
At 60 amps, that is 60 x 12.8v = 768w of panels. So you have double the panels the 150/60 can supply at 12v.
At 24v it could supply 1536w (roughly the size of your array).

Trying not to get too far ahead of ourselves, do you have an inverter to power your CPAP?
That will likely need to be a pure sine wave and be sized by watts for the CPAP.
And, it has to be for either a 12v or 24v battery. So your battery voltage decision will affect which inverter you need.

There are a couple of things I am not clear on regarding charging.
Can you say how, or provide a formula for figuring out the max charging amps for a given set of batteries.
Then, while charging, I have a 13.8v 60amp charging that is CC/CV.
Does CC mean that it is going to push 60 amps, even if the batteries are at full charge? If so, will this damage the batteries?
I just don't have a grip on charging yet.

 

[MisterSandals]

Can you say how, or provide a formula for figuring out the max charging amps for a given set of batteries.

The charging amps are specified by the battery maker. But in general, i think .5C is the preferred
maximum charging current (I will use Hedges number from post #35). Where "C" is the number of amp hours of your battery. At 12v you have 200ah so C = 200a. At 24v you have 100ah so C = 100a.
.5C is half of that: 100a, 50a respectively. Max! (this will stress the batteries a bit)

Does CC mean that it is going to push 60 amps, even if the batteries are at full charge?

The way I think about this is that amps are PULLED. Take for instance the electrical grid. If it pushed amps,
that would be quite a bit! Rather your appliances, pull what they need (or can absorb like battery charging).
As the battery fills, it will absorb/pull fewer amps as its voltage reaches the charge voltage.
(I am open to being corrected or given a better analogy!)

 

[Mark_B]

I'm still working out what I am going to do with the panels exactly, but I do have a battery question.
Can or should I put these inside my walk-in closet off the master bedroom?
It just happens to be at the exterior wall where many panels will be ground mounted.
I'm of course concerned about fires or any type of harmful gas leakage that the batteries might cause?
I can also easily put them in the garage, but the temps out there get hotter and colder. Never freezing or anything, but the heat is probably the greatest concern. It can get 100 deg F out there for maybe a month in the summer. It really gets the afternoon sun heat in there.

 

[MisterSandals]

I'm of course concerned about fires or any type of harmful gas leakage that the batteries might cause?

LiFePO4 is pretty safe from fire or exothermic reactions. If they get overcharged, they will vent
what has been described as a nasty smell but I think its non-toxic.
Any hazard having your electronics in your living space would likely depend on what supporting
electronics, fuses, wiring ... accompany your batteries.

Batteries sure do a lot better when in a temperature controlled environment though.

I don't think 100 deg F for a month is awful. Is it possible to put them in an insulated enclosure?
Something as easy as a styrofoam cooler may be enough. Even a few bottles of water in the enclosure
will make the temperature inside less reactive to the external temperature.

I cannot really say what I would do or whether i recommend them in a bedroom closet. Its almost certainly
not going to be up to code!

Can you build a doghouse outside, well insulated and shaded?

 

[Mark_B]

I received my 150/60 MPPT charge controller. I'm still waiting on my BMS boards. I'm going two 12v batteries in series, mostly because I want them to be easily portable if I want to take them camping, and 32 batteries combined in 24v package is just too heavy.
I am about ready to purchase an inverter, and have been trying to learn about that and figure it out.
Does a 2500 Watt (24v) sound about right for this 24 v 100 AH battery? I believe most of the use of the system will occur during the day when the 4 x 385 watt panels will be near full production.
I do want to go too big, or too small on the inverter and am just not clear what would be best.
I really appreciate all your advice here on the forum. More and more of it is making sense to me as I learn.