Need help with 24 Solar Setup

[Bert06840]

Originally Posted by kazetsukai

[*]I would look to see if any low frequency inverters fit the bill for your electrical needs, they'll be much better for surge loads. PowerJack makes some nice 24V LF inverters for low cost, my "8000W" ....

They have one huge disadvantage: quiescent current draw. They seem to draw about 80-100W on idle. That’s 2kWh a day. You need like half a kilowatt of panels an batteries to cover just that...

I might still buy one anyway, alongside the HF inverter. But not have it on 24/7. In case I need to power a cement mixer or something.

[Bert06840]

Originally Posted by Dre123

1.
But i also plan on getting the optional screen for the mppt.
I just looked at the app review for the xiaoxiang bms, and its scary. They're is a lot of bad reviews. I don't know if i should look for a better bms...

I would indeed get the optional Victron screen.

About the Xiaoxiang BMS. I bought the $5 or $10 iPhone app made by a Swiss guy.

It has worked absolutely flawlessly for me.

I also have the Android app, and that is of the Chinese-engineer-designed type. So yeah. The hardware is great, the third party SW is great, the native android software is meh.

I’ll take a screen shot, I’m microwaving noodles:

[Rucker]

Originally Posted by Bert06840

Even if they were allowed to cold soak, and I was unable to disconnect them, there’s still the low temp disconnect of the BMS.

Heater pads can be useful, but the complexity of doing heater controls from solar only (it makes less sense to do it from battery power), seemed not worth it.

Gotcha. I'm nowhere near the arctic circle and my default is to defer to the colddwellers who live it.

I'm wondering if the low temp disconnect includes disconnecting the charge circuit-that is crucial.

I picked up a couple of self-contained 12 volt heater pads for about 18 bucks apiece (I think). Plug them in, forget them kind of equipment. They are called pipe elbow wraps.

I don't intend to camp in the cold, more likely just drive up in the mountains from time to time, but just in case, I'll install those and an independent temp gauge 'cuz the cells cost so much.

[Dre123]

Originally Posted by Rucker

Nice level of detail, great research. That's what it takes.

I might have missed it but I didn't see lengths on your wires. AWG depends on amps AND length.

Other feedback/comments.

1. I couldn't find the exact MPPT device, there's a 150/70, so I'm wondering if you're looking at an old spec sheet for the controller.
2. Others here have commented it is not good to have a disconnect switch between the charge controller and the battery bank. Sounds weird, I know, but they have compelling arguments (related to power surge from the solar array).
3. Batteries-LiFePo? Consider adding heating elements because you live up north.
4. Is that a Victron SmartShunt? Hopefully yes? Consider the bluetooth version for ease of viewing. I see the other comment saying it's not needed because of your BMS...not really sure about that.
5. Solar panels. You may want to consider tilting frames because research shows folks up north lose as much as 25% of solar gain due to latitude. Others have made really good points in other posts, which I agree with.

1. Here is the spec sheet: https://docs.google.com/viewer?url=h...N.pdf&pdf=true


2.I think i will go with a combiner/breaker box instead. Its more convenient that way i think.


3.Yes i will use a heat pad designed for snakes/lizards pets, i just have to find one activated by a thermostat or hook up a thermostat myself to the heat pad.


4.Its a Chinese knock off on the diagram, if budget allows i will go with the victron.


5.Ill have to look into it.

[Dre123]

Originally Posted by Bert06840

Well, then you wake up to a depleted battery. No problem! Your BMS will shut it off when needed.

No harm will be done to your batteries IF YOU CONFIGURE IT CORRECTLY.

Did you say hot humid nights? Is there a Canada, FL?

I swear some nights its like the wind is dead, you can even catch a small breeze.

[Dre123]

Originally Posted by Bert06840

Here’s my 150/70 that just showed up minutes ago.

Attachment 57680


Oh boy, it’s massive compared to the 75/15. On the internet they all look the same.

Looking good

[Dre123]

Originally Posted by Bert06840

I would indeed get the optional Victron screen.

About the Xiaoxiang BMS. I bought the $5 or $10 iPhone app made by a Swiss guy.

It has worked absolutely flawlessly for me.

I also have the Android app, and that is of the Chinese-engineer-designed type. So yeah. The hardware is great, the third party SW is great, the native android software is meh.

I’ll take a screen shot, I’m microwaving noodles:
Attachment 57688

Nice
I have an old iPad somewhere that i could use for that if the app is compatible with IOS 10.3.3.

[Bert06840]

Seems you’re in luck

[Bert06840]

Originally Posted by Rucker

I'm wondering if the low temp disconnect includes disconnecting the charge circuit-that is crucial.

It ONLY disconnects the charge port. Discharging while subzero is not a problem!

The anode gets plated with metallic lithium when you apply a current to an LPF cell when freezing, causing a short and permanently killing it.

[Dre123]

Originally Posted by Bert06840

Attachment 57689
Seems you’re in luck

Thanks

[Dre123]

Originally Posted by kazetsukai

Watts are a derived unit. You're thinking of amps. 12A 120V AC will be 60A 24VDC, roughly.



Thoughts to OP:

• Mini split: Even the 970W rating, it blows out your energy budget in a short few hours. Assuming you didn't add the split to that number?
• I would look to see if any low frequency inverters fit the bill for your electrical needs, they'll be much better for surge loads. PowerJack makes some nice 24V LF inverters for low cost, my "8000W" (realistically, 3500W continuous) 24V cost me right around $350 IIRC. They are also split phase- a plus if you want your panel to be wired like residential service, and intend to install 50A RV inlet. Just an option!
• Instead of using inline solar combiners, consider a PV combiner box, which will come with fuses/breakers and usually lightning arrestors/grounding equipment.
• Speaking of which, you show an AC panel and inverter but I don't see any RV style inlet. Intentional? It is quite convenient to have either a 30A (120V) or 50A (240V) inlet.

Looks pretty good overall.

I will do some more research. I completely forgot about charging from shore.
Would the Victron Blue Smart IP22 Charger 24v 8A would work for that purpose?

[Bert06840]

If you want shore charging, then the Growatt or MPP Solar all-in-one units become interesting.

They are not best-in-class in anything, but they cost about one third of discrete inverters, charge controllers, and AC/DC converters by Victron.

[Dre123]

So for my question regarding if the ground bus bar should be connected to the frame or not, i found my answer on the CSA Z240 RV Series of Standards.


Page 135 5.14.1 / 5.15.3


Basically the only thing you can and need to ground is the 120V breaker sub panel. Anything else you cannot ground to chassis.

[Dre123]

Originally Posted by Bert06840

If you want shore charging, then the Growatt or MPP Solar all-in-one units become interesting.

They are not best-in-class in anything, but they cost about one third of discrete inverters, charge controllers, and AC/DC converters by Victron.

I might just skip on the shore charging, its an extra expense and i don't think it will be very useful for us after all.

[kazetsukai]

Originally Posted by Bert06840

They have one huge disadvantage: quiescent current draw. They seem to draw about 80-100W on idle. That’s 2kWh a day. You need like half a kilowatt of panels an batteries to cover just that...

My current one is a 48V 8000W momentary/4000W continuous), draws 45W constant at idle. Power save mode brings it down a bit further. 24V and 12V inverters are less efficient.

Removed it yesterday, upgrades in progress.

Originally Posted by Dre123

I will do some more research. I completely forgot about charging from shore.
Would the Victron Blue Smart IP22 Charger 24v 8A would work for that purpose?

24V 8A is 192W, so it might take a while especially if you have a largeish battery bank! To put it in perspective, it would take 6-12 hours just to charge a pair of 12V 100Ah batteries in series from empty to full.

This is a good reason to pick your inverter wisely, the LF inverters I mentioned will charge your batteries much faster than that... Not only that, they'll handle the shore transfer process in many cases- when you plug in, they automatically change your outlets over to shore power for you and begin charging the batteries all in one step.

Inverter charge options there I know of:

• Victron MultiPlus is a solid unit for transfer switch / charge, Victron EasySolar combines the inverter/solar in one package. They're bulletproof, really, just depends if you can swallow the up front cost. If you can, you can't go wrong here.
• PowerJack is a great budget option will charge lead acid/AGM/Gel and act as a transfer switch on some models. I think all models with charge are configured all to charge from 120V. I don't currently use mine for charge because its charge voltages are not suitable for my current (Tesla) battery bank, few are. Thus before I could recommend any of these for charging lithium of any kind, I'd have to know the battery bank info and look at the spec sheets of current offerings.
• Genetry Solar makes a 6000W inverter true to rating with configurable bulk/absorb/float voltages, built in transfer switch and charger configured for either 120V or 240V at shipping. This is what I'm upgrading to when the rest of my new battery bank arrives next week (LFP).

If you _just_ want a charger, 12V-24V the AIMS one is the one I'd recommend:
https://www.amazon.com/AIMS-Power-CO.../dp/B07N1K43NQ

Read the spec sheet, make sure it has settings that are compatible with your battery chemistry and configuration. In doubt, post the details of your batteries and ask.


Edit, just saw this:

Originally Posted by Dre123

I might just skip on the shore charging, its an extra expense and i don't think it will be very useful for us after all.

Have you ever lived off solar/off the grid? Even if you have extensive experience doing so there are lots of good reasons to have an inlet of some kind- if you're ever doing work on your battery bank, if you want to use generator power, or you just run into a string or rainy days it is hella useful. Up to you, and you can always add one later, just easier to do now rather than when you need it immediately imo.

Takes a while to get used to working off solar power. For us, its the overnight AC that puts us over budget- the bottleneck being the batteries. Everything else has a two or three day overcast runtime, and your system having similar capacity should be around the same.