First timer with small cabin setup

[medic149]

First off, thank you to everyone who posts on this site and for the people who have been helping me so far.
I am learning a huge amount. So much that I might be getting myself confused lol.

We have a 320 sq. ft. off-grid cabin with a Jayco 29' camper on site and would like to go solar.
The plan is to spend 3 or 4-weeks and then a bunch of weekends at the cabin. Probably around 40-45 days or nights a year.

We plan on using our 2 Honda 2200i generators, which can be run in parallel, for our initial energy needs and charge a battery storage system when the sun isn't shining enough.

I used snoobler's excel spreadsheet, which was great, but not sure if my numbers are accurate.

Here is my first attempt at a design. Let me know if I am heading down the right path or not:

Minimum System size calculations​
Full Load Wattage	3158​	Watts
Full Load W-hrs.	7152	W-Hrs.
Full Surge wattage	1075
Inverter efficiency	96.00%	%
Full Load Inverter size (input watts)	3290	Watts
Full Surge load Inverter size	44	Watts
Daily Storage Requirement	4000	W-Hrs/Day
Max discharge from full CHARGE	90.0%	%
# days of storage capacity	2.0	Days
System Voltage	48.0	Volts
min Battery capacity W-Hrs	8888.9	W-Hrs.
min Battery capacity A-Hrs	185.2	Amp Hours
Max continuous current from bat.	68.5	Amps
Max Continuous discharge rate	0.37	C
# sunny days to recharge while under load	1.0	Days
Required Total daily Solar output (Sunny)	8000.0	W-Hrs.
Insolation # (Equivelent hours of full sun)	4.0	Hours
Min Solar Cell Wattage	2000.0	Watts
Max Charge Current	41.7	Amps
Max Charge rate	0.22​	C

Even though I entered 2-days of energy storage, I am fine with 1 day and using generators as-needed.

Considering this setup:

• 5 panels - Q.PEAK DUO L-G8.2-430 (430 Watt Mono G8) 24V
• HYBRID LV5048 Split Phase 120V/240V output 5kW 48V, Dual 4kW Solar MPPT inputs (8kW)
  

  HYBRID LV5048 Split Phase 120V/240V – replaced by LV6048 – Watts247.com

  watts247.com
• 2 - SIMPLIPHI POWER PHI 3.8KWH LITHIUM (LFP) BATTERY, 48V
  

  SimpliPhi Lithium Deep Cycle Batteries

  SimpliPhi Lithium Ferro Phosphate (LFP) Deep Cycle Batteries are safer than lead acid batteries with a much longer cycle life.

  www.altestore.com

I am still a newbie to all of this and learning more and more every day.

Thank you for all the help.

AJ

 

[Hedges]

Include no-load power of the inverter 'round the clock. Looks like that's < 10% of what you've listed.

https://watts247.com/manuals/mpp/LV5048%20split%20phase%20manual-20191024.pdf

Standby Power Consumption <23W

Battery $2500. (each)
About 2x the price of 5kWh AGM battery I bought, which has similar usable capacity but shorter cycle life. Probably same lifespan given your usage.
$5000 is a lot of money to spend on batteries. That's what I paid for 20 kWh of AGM (14 kWh usable)
You can build DIY lithium for same or less than my AGM.
As you note, smaller battery is OK if you have generator for backup.
Once you decide generator is OK, you can make battery even smaller. Just enough for the night. Run loads directly off PV while the sun shines (e.g. refrigerator)
What about 4 of these for $1300 total?

Sun Xtender PVX-1040T AGM Sealed Battery

Sun Xtender PVX-1040T AGM Sealed Battery

www.solar-electric.com

How cold does your location get?
Lithium can't charge below freezing. But it retains most of its capacity.
AGM shouldn't be discharged too low if freezing possible.

 

[medic149]

I do like the idea of AGM batteries. Just keep seeing a lot of people heading to Lithium. AGM might be a good choice for me with the number of times we'll be at the cabin. Also since I'm already in my late 50's lol. I've also seen the videos on building Lithium, which looked pretty interesting as well. The Sun Xtenders look like a good option for me.

The cabin is in Camden, NY north of Rome. It's about 3 hours from where we live and we close on it in a couple of weeks. They tend to get a lot of snow. The temps are what I am concerned about for the winter months when we won't be there:

January	February	March	April	May	June	July	August	September	October	November	December
Average Monthly high in °F:	28°	31°	40°	54°	67°	75°	80°	78°	71°	58°	46°	33°
Average Monthly low in °F:	9°	10°	19°	33°	42°	52°	56°	55°	47°	37°	29°	18°

I was thinking of getting a camper black tank heater blanket to place under the batteries to just ward off some of the extreme low temps.
Figuring I wouldn't be using the cabin in the coldest winter months is why I was thinking Lithium, but AGM with the heating blanket and no usage, other than the heating blanket, that might be good.

Thank you for the help! I can talk myself round in circles with some of this lol.

 

[medic149]

While I was searching on climate information, I came across this link, which seems pretty good: https://weatherspark.com/y/23162/Average-Weather-in-Camden-New-York-United-States-Year-Round

 

[Hedges]

Heating blanket would drain the battery and let it freeze, unless disconnected while battery still had charge.

Fully charged, the AGM battery will make it through the winter without freezing and without needing to be charged.
You can still turn the lights on when you get there, and as you warm the cabin up you'll have more power. Make sure it's charged again and all loads (including inverter) are shut off before leaving.

+9F ain't nuthin', SunXtender OK at 25% SoC without freezing.
-53F, needs 75% SoC
If your location dips below -94F, consider burying the batteries underground.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

Determine record cold temperature (I haven't found that for Camden) and use to adjust Voc from PV panels, make sure it won't exceed spec of charge controller.

 

[medic149]

Thank you Hedges!! If it gets down to -94F, we got more problems than the batteries LOL.