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Off Grid desert nest

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scrubjaysnest

Solar Enthusiast
Joined
Nov 15, 2023
Messages
267
Location
Florida and Arizona
Going in a smaller direction then Goose. Our nest is 1 acre at 6400 feet, bought it already fenced, with a shed and water storage tank. Also had septic system the size Goose is planning.
RV has 500 watts of solar and there were 2 240 watt Trina panels in the shed.
Since the RV only needs 200 watts in the AZ desert that gives us 780 watts of panels to use. Also have another 500 watts here in FL to go back out to AZ in the spring. Total wattage to start is 1280 if I did the math right.
After a lot of dithering pulled the trigger yesterday for 4 12 volt 100Ah AOLITHIUM with Bluetooth and low temperature cutoff. Price less then 4 good 125 Ah AGM's. I have a TS 45 PWM and Victron 100/20 MPPT. That is .1875C but close enough to .2C for now.
 
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Looking at getting a pair of Victron 100/20 cc's. Price less then a single 100/50. Con is 10 amps less but pro is the pair can be changed to 48v at a later date. So many things to think about. A 250/80 might be best but not anywhere near the budget.
 
New AOLITHIUM 12v 100ah batteries arrive today. Bad thing is the way I can cycle them is 300 watt inverter and morningstar sunsaver duo. Have enough solar to produce 0.25C at 14.1 volts. Any thoughts if that is enough?
 
Batteries came yesterday. Had trouble getting the App to work but ok after deleting and rebooting the tablet. App is fairly limited, shows soc, voltage, and average cell volts. Also internal temperature.
Borrowed a lithium battery charger from a neighbor to get the initial charges done.
 
Not sure I like the AOLITHIUM app, doesn't show individual cell voltage and can only look at 1 of 4 batteries at a time.
Using the Liontron I can monitor 3 at once, the 4th is out of range. Liontron shows individual cell voltages which is a plus for me. Have 1 battery on charge, 1 doing 1st discharge into 216 watt load, and the 3rd is sitting idle. App auto switches between batteries. Like it better so far.

Any other apps I should look at?
 
I have decided to go with 3 ground mount arrays. 2 will be 4 100 watt panels and the 3rd will be made from the 2 used Trina 240 watt panels. Each array will have it's own mppt cc. At the present time thinking the Victron 100-20 will be my best choice both from redundancy and cost. I will have to pay attention to input Voc for any series panel connection. The system will start as 12 volt and maybe changed to 24 volt with a dc to dc for 12 volt applications.
1 ground mount will be the existing wood frame for the Trina panels, raised a little higher off the ground and well anchored. The 2nd will be metal frame starting with 4 100 watt panels and expansion to 12 100 watt panels. The 3rd will be made up of 3 100 watt panels that are portable for the rv plus a 4th 100 watt panel.
 
Did my 1st rough cut on system losses today. Used a modified version of solar-guppy's xl spread sheet from several years ago. Looks like array 1 needs to be 3s2p made up from 100 watt panels. That way I can use 12 awg 105 c marine grade wire and keep losses below 2%. Getting 2 more panels for array 1 keeps everything the same. Array 2 will use 3 of the motor home panels in series and Voc will be almost identical to array 1. No extension were needed for array 2.
Array 3 will be the 2 Trina panels in series, Voc on array 3 will be almost 75 volts.
Again I can use 12 AWG wire.
 
Concho valley, or Ashfork / Williams area? Are you concerned about leaving solar there when your back in Florida? Thieves look for property not occupied regularly.
 
scrubjaysnest said:
Concho valley. Property fenced and security cameras. Watched the snow falling earlier. Neighbors aren't close but go by at least once a day.
Click to expand...
Wife's friends lived in the Concho area since the 1980's we go up and visit they have an 80-acre ranch. Unfortunately, the sheriff not to responsive although not surprising in a county with low tax rates deputies pay is low. Just the distance thieves know even if you see them on camera, it will take an hour or more for a deputy to get there. That is if there aren't any other calls which take a higher priority than a burglary. If you can get to know your neighbor that would help, then you can call them when you see something going on. In return you do the same this is what our friends do they been there so long they know everyone. We will be heading up next week doing some tree thinning with my new chainsaw. We're looking in the Alpine area always wanted to build an off-grid cabin. Need to see if we can handle the high altitude, it's about 8800 feet up there.
 
Honey Badger Ranch (HBR) is near Concho Valley. :)

While I've not been affected in the last 4 year, nor has my neighbor for the last 30 years, theft in the area seems pretty pervasive. The size of your property seems to play into it. Big properties seem to be less affected. Fences and especially electric fences help too.
 
scrubjaysnest said:
New AOLITHIUM 12v 100ah batteries arrive today. Bad thing is the way I can cycle them is 300 watt inverter and morningstar sunsaver duo. Have enough solar to produce 0.25C at 14.1 volts. Any thoughts if that is enough?
Click to expand...

Lithium doesn't care about the C rate unless it's OVER the maximum. Will take 100 hours, but .01C is fine.
 
The order arrived today so I tacked in 2 panels and 100/20 to 1 of the aolithium batts. Vin was at 32 volts and 1.5 amp. Air temp 69 deg F Not to bad as panels are almost flat and not in the direct sun. Rain tomorrow so won't see much then either. Cells were getting close to 3.4 volts for the 1st time.
Edit said vmp when it was cc input voltage. Open was 40 volts, Voc for these panels is 22 volts
 
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Got low end results, 32 volts and .3 amp into the CC. 13.46 v at 0.7 amp out of CC. Klein clamp on and JBD BMS agreed. Ambient air temp 67 deg F and overcast. 1 point obtained.
Attached partial pic of ground mount in progress. It will have 6 100 watt panels when I reassemble it in AZ.
 

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Just had a brain f**t. So use to dealing PWM it just got through what I was seeing with 60 volt input and and up to 2 amps out for an input I of 0.5 amp. Ooooops!
If the panels produce 300 watts into the MPPT that becomes 300/ 14.4 = 20.83 amps out of the MPPT. There goes the idea of 3s2p. Be safer to go 2s and a single string because of the number of days with temps below 77 deg F.
 
scrubjaysnest said:
Just had a brain f**t. So use to dealing PWM it just got through what I was seeing with 60 volt input and and up to 2 amps out for an input I of 0.5 amp. Ooooops!
If the panels produce 300 watts into the MPPT that becomes 300/ 14.4 = 20.83 amps out of the MPPT. There goes the idea of 3s2p. Be safer to go 2s and a single string because of the number of days with temps below 77 deg F.
Click to expand...

In our area rated Voc of 80V or less will be fine on a 100V controller, but at 14.4V, 2S may be a little more efficient if you don't have long PV wire runs.

The 100/20 will limit output to 20A regardless of panel configuration. You simply don't want to exceed the PV input current limit and Voc published in the datasheet.
 
sunshine_eggo said:
In our area rated Voc of 80V or less will be fine on a 100V controller, but at 14.4V, 2S may be a little more efficient if you don't have long PV wire runs.

The 100/20 will limit output to 20A regardless of panel configuration. You simply don't want to exceed the PV input current limit and Voc published in the datasheet.
Click to expand...
1 thing I'm considering is set the battery bank up as 24 volt. Means buying a different inverter and dc to dc converter for a few 12V items like the water pump.
Move the 12V inverter to the RV for the microwave.
Voc for the new panels is 21.8, round it to 22 and 3 panels is 66 volts in series.
The older 12 volt panels have Voc around 20 volts. And the 2 240 watt Trina panels are about 37 for Voc so a 24 volt bank may be a better choice.
Some will say just goto 48 and be done. That's what White Mountain Solar is suggesting.
 
scrubjaysnest said:
5 deg F in showlow this morning so far. It will be similar at the desert nest.
Click to expand...

My weather station is currently reading. 3.4°F with a low of 2.7°F logged at midnight.

Brrr....

1704809438211.png


scrubjaysnest said:
1 thing I'm considering is set the battery bank up as 24 volt. Means buying a different inverter and dc to dc converter for a few 12V items like the water pump.
Move the 12V inverter to the RV for the microwave.
Voc for the new panels is 21.8, round it to 22 and 3 panels is 66 volts in series.
The older 12 volt panels have Voc around 20 volts. And the 2 240 watt Trina panels are about 37 for Voc so a 24 volt bank may be a better choice.
Some will say just goto 48 and be done. That's what White Mountain Solar is suggesting.
Click to expand...

I'll be blunt. 48V pays off in the end. It completely removes barriers to expansion and maximizes your MPPT yield, though you need to select a 48V capable unit.

My neighbor has a 24V system originally specced out in the 90s, and it's been carried forward. With 4kW solar, he needs 2X 80A controllers. I only have 2kW mounted, but my single 100A can handle the installed plus the 3kW I have planned for mounting. Furthermore, as his demands have increased, he had to add a dedicated 24V/6kW inverter for his well pump, so it's something of a cobbled together setup. Works fine, but 48V would have expanded his options.
 
That is the nice thing about the Victron 100/20 click and grunt, it's now 24 or 48 vdc.
Yesterday's snow ❄ pic
 

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Waiting for some heat before I can charge my batteries!!!!

1704811244781.png

At 0°C, the system will use PV to power the loads. At 5°C it will charge. I can manually turn on/off a 1500W space heater in the container, but it doesn't do much since the container is uninsulated. Once it's at least 0°C, the PV can power the heater, and it seems to get me to charging temperature about 30 minutes faster than the sun heating the container can.
 
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