Brown bear destroyed our yurt powered by Yeti 3000, so I'm designing solar for a cabin & a bit lost

AlaskanNoob

New Member
Yes the 15A is max battery charging output.

It's simple. I updated my last post.

To size a SCC take the total wattage then divide by battery voltage.
600w ÷ 12V is 50A
600w ÷ 24V is 25A

A 24V battery would halve your SCC amperage saving money and allowing smaller gauge cheaper wires.

Those small 100 watt panels and 12V battery is going to cost you.

Wire size from panels to SCC.
Enter
Vmp total of array
Amps total of array
One way distance.
Under 3% is good.
I doubt if your distance is that much.

I think I'm now ready to try to understand this better. I'm limited to a 12V battery bank due to the "low temperature" requirements of the Relion batteries I'm using.

I'm under the assumption that I can have regular old MC4 wire from the panels to the SCCs. That's the way I do it with the 1600 watts of panels connected to our two Yeti 3000s. But given that the voltage and amps will be higher with these larger panels, perhaps my assumption is incorrect?

I'm also assuming that with the SCCs mounted just above the 12V battery bank, that while the wires may need to be thicker, it will be a short distance and so not too costly.

I haven't put any thought into the wires obviously, so thanks for any continued education. The longest run from a solar panel to a charge controller will be under 30 feet in our case.
 

the_colorist

"Move over... let me fix it"
Sorry to hear about your yurt. Alaska is so pretty from what I'm told and yet so chilly. You're braver than I for sure!

I'm probably too late to the thread but as an installer I think there might be a cheaper way to do this. Even with my installer/dealer pricing and discounts I'm glad to give forums members, you're looking at a crazy high bill as was mentioned already. Plus a lot of wiring. If you're intending to buy an inverter or inverter(s) to use with your Relion batteries though, we can reduce your cost quite a bit. And even if you're not, we can still probably shave a few hundred or more off if you're interested.

Before I flesh that out though (if you have interest), are you intending to buy an inverter(s) or are you looking to reuse your yetis?
 

AlaskanNoob

New Member
We're intending to buy the panels, the nine charge controllers, and a DC-DC charger and an inverter. I think we're going to go with two battery banks. A single 12V Relion LT battery for one battery bank, and two 300AH non-LT Relion batteries for the second bank (wired in series for a 24V system). One of the strings and charge controllers will charge the 12V LT battery bank, all the rest will charge the 24V battery bank. We'll have a DC-DC charger on the LT that will also charge the 24V battery bank when the 12V battery is full.

I think we'd rather go this way so that we can expand our battery bank as needed over time and not be locked into a 12V system. But we want one low temp battery as part of the system for powering security stuff in the winter.

I'm planning on installing it myself unless I come to the conclusion that it's too cosmic. I need to figure out the wire gauge from panels to the charge controllers, and then wire gauge from the charge controllers to the battery banks, shutoff switches for each PV array to the SCCs, and perhaps select a "trough" for the wires running from the SCCs to the batteries and such, but I would think I could do this myself but I'm just learning.
 

the_colorist

"Move over... let me fix it"
The switch to 24V will definitely help with reducing the number of charge controllers since you only need half the charging current (amperage) you would need for 12V.

If you are considering installing Victron Multiplus or Quattro inverter/chargers, depending on the model, each one has a charging capacity of between 50A-120A (models 2000VA-5000VA). Rather than let that charger go unused unless you're running the generator, you could AC-Couple the Multiplus/Quattro with a PV inverter.

Here is a quick diagram I modified from Victron to represent your 24V system. You'll several other things (possibly auto-transformer unless you use 2x inverters etc) but it will give you an idea.

1614546044450.png

That's just one configuration and again it's missing several things. Another would be to use the AC-Out 2 on the Multiplus/Quattro for the PV inverter and that's likely what I would recommend. I didn't get to review the entire thread to make a complete layout but there is a chance this will be cheaper for you than running several charge controllers. Many PV inverters have multiple MPPT trackers so you can vary your strings size or types of panels per string. If you're using SolarEdge with optimizers, that will help with varied light per panel and mixing panel types. Will be much less wiring to deal with as well, since your string voltage(s) can be just shy of 600V.

The wired AC sensor is to prevent power from pushing back to the generator but there are other ways to do that as well that might be easier to setup.
 

curiouscarbon

Solar Addict
Hello and sorry to hear about your yurt.

Recommend 24V battery system strongly.

built in heater on relion sounds hard to beat for simple

building a battery enclosure with 4” of insulation and putting a small heating pad on the bottom (cold ground) is an option many on the forum have considered or built. be sure to get type that prevents ice, not a water heater. they are thermostatically controlled which means no complicated electronic heat control needed. eg 100 dollar on foam insulation might go further than 100 dollar on specialized battery with internal heater.

edit: links
insulation example: https://www.homedepot.com/p/Thermas...-Rigid-Foam-Insulation-Board-613010/100573703
heater pad example: https://www.amazon.com/Facon-Holding-Trailer-Automatic-Thermostat/dp/B01MT9EUG9

only mentioning this because it could lower battery cost and lower SCC cost a lot with a little preparation

i’ve run a small 12V outdoor DIY solar system for a few year now (1KWh storage, 0.6KW panels) and even at this tiny scale, my robust victron blue solar 150/30 mppt cannot utilize the entire solar potential. right now 30 amp * 14.1V = 423W max. after upgrade, 30 amp * 28.2V = 846W max.

that thing wasn’t cheap either. planning to switch from 12V to 24V very soon to capture more solar power (using frey 100Ah cells and JBD/overkillsolar BMS).

anyways going to 24V will give you double the charger per dollar in a sense

x dollars per output amp of SCC capacity
 
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Nakinto

New Member
Sorry to hear about the bear. Are you putting these batteries outside? I keep my batteries inside, WA state, not nearly as cold as Alaska, but still close to 0F outside through winter, inside never below 50, don't even need to worry about the freezing. If you are keeping them inside the cabin you could go with just about any LFP battery with a low temp shutoff, incase you loose heat inside for a spell. Battle Born, heck even SimpliPhi, are far cheaper then the planned Relion and they come in 24 and 48v configurations.

Winter panels up there is a great idea, they will produce during summer also, not as much, but they will and it is the winter when you need the power the most, as you clearly already know.

If you already have the 100w Renogy panels, use them, no problems.
 
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