About to start an off grid project

[Homeless]

First time poster, glad to be here
I have an off grid cabin that has no AC. I need to install 2 of the solar panels shown in the attached photo. These are brand new panels but I bought them a few years back and they have been in my home office since purchased. I am sure the technology has surpassed these two panels but I need to use them anyway.

All I am looking to power right now is a 12V to 5V power supply. I am installing a cellular hot spot for the internet and a couple of the WYZE cameras so I can keep an eye on the cabin while not there. So, my plan is to connect these panels to one or two batteries (thinking two regular car batteries or one 100 AH 12V Lifepo4 deep cycle battery). I believe the solar panels should keep the battery(s) charged more than the small drain that the cellular hot spot and two usb cameras will draw. The cameras draw 5V/1000mA each and I am not sure yet on what the hot spot will draw since I have not purchased one yet. I thought this would be better using the 12v to 5v power supply to draw less power than an inverter to run AC then plug the USB charge adaptors.

The 12v converter is a 25W DC-DC converter, input 12-24 V and output is 5 volts @ 5A max. If needed I can get a larger converter.

Any tips or things I have forgotten, or will not work as I described is really appreciated. I am familiar working with AC and electronics but solar is new to me
Thanks in advance

​

 

[Hedges]

Charge controller, to take the variable voltage from PV panels and deliver the charge profile needed by batteries?

Charge Controllers | SanTan Solar

store.santansolar.com

Does your location drop below freezing? if so, LiFePO4 can't charge below freezing.
AGM can take the temperatures. Its lifespan in cycles and years will depend on depth of discharge.

 

[Homeless]

Charge controller, to take the variable voltage from PV panels and deliver the charge profile needed by batteries?

Charge Controllers | SanTan Solar

store.santansolar.com

Does your location drop below freezing? if so, LiFePO4 can't charge below freezing.
AGM can take the temperatures. Its lifespan in cycles and years will depend on depth of discharge.

Thanks, Yes I forgot to mention that I already have this charge controller. It should have ample capability for me to grow and ad more panels and batteries as I move forward this summer

 

[Hedges]

Good, that'll support several panels in series.

As for batteries, you mention regular car batteries or LiFePO4.
Car batteries won't last long if cycled to significant depth of discharge. I use AGM of this brand:

Sun Xtender Solar Batteries - Photovoltaic Battery

The Sun Xtender Battery line consists of specialty lead-acid solar, photovoltaic batteries, and renewable energy storage batteries manufactured by Concorde Battery Corporation.

sunxtender.com

Lithium has the issue of not tolerating charging below 0 degrees C, expense, and needing a BMS.
You might consider lithium, possibly DIY, when you plan for heavier use.

I suggest AGM for simple system while your only use is the cameras. So long as you have enough PV to carry load and fully recharge the batteries, and batteries are sized appropriately, you can pick the cycle life and price you want.

5V cameras seems a bit unusual, I think security systems usually have 12V to the cameras.
Voltage drop occurs somewhere, because the ICs are lower voltage.
An efficient switcher in the 12V to 5V adapter is important because output voltage is 40% of input. Find out what its input current is in order to size the battery.

 

[Homeless]

Good, that'll support several panels in series.

As for batteries, you mention regular car batteries or LiFePO4.
Car batteries won't last long if cycled to significant depth of discharge. I use AGM of this brand:

Sun Xtender Solar Batteries - Photovoltaic Battery

The Sun Xtender Battery line consists of specialty lead-acid solar, photovoltaic batteries, and renewable energy storage batteries manufactured by Concorde Battery Corporation.

sunxtender.com

Lithium has the issue of not tolerating charging below 0 degrees C, expense, and needing a BMS.
You might consider lithium, possibly DIY, when you plan for heavier use.

I suggest AGM for simple system while your only use is the cameras. So long as you have enough PV to carry load and fully recharge the batteries, and batteries are sized appropriately, you can pick the cycle life and price you want.

5V cameras seems a bit unusual, I think security systems usually have 12V to the cameras.
Voltage drop occurs somewhere, because the ICs are lower voltage.
An efficient switcher in the 12V to 5V adapter is important because output voltage is 40% of input. Find out what its input current is in order to size the battery.

Thanks for the feedback
The cabin probably does drop below freezing inside since there is no heat, however, I went up there this past weekend expecting the bottles of water stored there to have frozen when it got down to the lower single digits a couple weeks ago. If they did freeze, none showed any sign that they had. If it does go below freezing and the BMS stops charging, will it resume when the temp gets above freezing? nothing gets damaged does it?

Also, the cameras i am using ( I have over 20 of them in two different locations) are wireless and the 5V powered USB is all that is needed for them to operate...;so as long as I keep the hot spot up and 5v to the cameras, it should work

The following is from Amazon questions where I purchased the power supply. It is talking about 3A output and the one I have is a 5A output but can get the general idea. Now that I think about it, I maybe should go up to about 10A . The cameras will use ~1A each (X2) and the hot spot will use another 3 or so.

The input on the plugin USB power supply that comes with the camera says input 100-240V~50/60Hz 0.35A Max input.
Output says 5V DC---2000mA I was incorrect in my original post that said 1000mA

Your thoughts?

The current x voltage output is roughly proportional to the current x voltage input (there is some loss due to inefficiency). For every amp drawn on the output you can expect a bit more than ~.42 amps on the input (a bit more because some of the energy is lost as heat in the device itself). so if you are drawing the full 3 amps on the output you can expect the converter to draw a bit more than ~1.26 amps on the input. I would recommend at least a 1.5 amp 12 volt supply - though that is assuming you are planning to use all 3 amps available on the output side.
I don't know exactly what the loss is, but the extra .25 amps should more than account for it.

 

[Hedges]

BMS may interrupt charging below 0 degrees C. It would reconnect the charging terminal when the battery warmed up.
It would also interrupt if voltage too high.
BMS may allow loads to continue drawing current below 0 degrees C. It would disconnect them if over-current or low voltage.
Unless it has only one terminal for both charge and discharge (e.g. a "drop-in replacement"), in which case your cameras get shut off in the cold.
No guarantee a BMS actually does disable charging at low voltage; if not the battery would quickly be damaged.
Up to you to read specs (and reviews) to determine what you're getting.

After you determine the Ah capacity you need and how low you will drain the battery, I suggest comparing AGM. For a small system it may be more economical and trouble-free. Trade-off is potentially longer life of lithium if you size for deep cycle every night and if it performs as advertised. I think that sizing for 3 days without sun can give AGM a 10 year life, negating any benefits of lithium.

20 cameras at 1 amp each? so 20A x 5V = 100W, for an 18 hour winter night is 1800 Wh?
In that case, assuming 100% efficiency of the 12V to 5V converter, a 200 Ah 12V battery for 2400 Wh would discharge 75% each night.

Unless you mean 2 locations, each with 10 cameras drawing total of 1A for 10 cameras.
1A at 5V sounds high for a CMOS camera.

Note you're looking at AC input and rated output of an adapter, which would meet or exceed consumption. Maybe peak consumption under some conditions with average being much lower.

The cameras are wireless (for data), but powered by wires from the battery?

 

[BobK]

I think you will be fine. I too have off grid cabin (shotgun shack) lol. Using solar, epever mppt, 2 6volt golf cart bats. I used the little 12vdc to 5v usb modules off ebay and all running 4 wyze cameras, internet modem, netgear wifi, for about year, no problems. When did have really bad weather, no sun form days, system did go off line, but all rebooted when sun came back.. I skipped ac inverter, run dc straight, saving power! Good luck!

 

[Homeless]

BMS may interrupt charging below 0 degrees C. It would reconnect the charging terminal when the battery warmed up.
It would also interrupt if voltage too high.
BMS may allow loads to continue drawing current below 0 degrees C. It would disconnect them if over-current or low voltage.
Unless it has only one terminal for both charge and discharge (e.g. a "drop-in replacement"), in which case your cameras get shut off in the cold.
No guarantee a BMS actually does disable charging at low voltage; if not the battery would quickly be damaged.
Up to you to read specs (and reviews) to determine what you're getting.

After you determine the Ah capacity you need and how low you will drain the battery, I suggest comparing AGM. For a small system it may be more economical and trouble-free. Trade-off is potentially longer life of lithium if you size for deep cycle every night and if it performs as advertised. I think that sizing for 3 days without sun can give AGM a 10 year life, negating any benefits of lithium.

20 cameras at 1 amp each? so 20A x 5V = 100W, for an 18 hour winter night is 1800 Wh?
In that case, assuming 100% efficiency of the 12V to 5V converter, a 200 Ah 12V battery for 2400 Wh would discharge 75% each night.

Unless you mean 2 locations, each with 10 cameras drawing total of 1A for 10 cameras.
1A at 5V sounds high for a CMOS camera.

Note you're looking at AC input and rated output of an adapter, which would meet or exceed consumption. Maybe peak consumption under some conditions with average being much lower.

The cameras are wireless (for data), but powered by wires from the battery?

Thanks, I must have not been clear when I said I had 20 cameras. That is in two locations that have power, my work and home. I am just putting 2 cameras at the cabin and will not add more until I get the solar and batteries upgraded to a level that will power more cameras and other items.

I also have a wind mill that I want to add to the system after I get it configured and running. I will look into the AGM for start up but plan on adding the LiFePO4 batteries later. Time is of the essence right now so I am setting up a minimal system to support the cameras only.

Yes the cameras are wireless for data and they are powered by 5v that originates from the battery. 12v battery connected to a 12v to 5v converter then connected to the cameras. in addition, it will power the hot spot so there is internet for the data.

BobK mentions a very similar system to what I want to put together. BTW I do have a generator up there but am not there frequent enough to charge the batteries if needed so I want to rely on the solar panels for long periods of time between visits

Thank you for all your info, I must learn this stuff, I have a pop up camper that I want to upgrade and also another cargo trailer to upgrade as well

 

[Homeless]

I think you will be fine. I too have off grid cabin (shotgun shack) lol. Using solar, epever mppt, 2 6volt golf cart bats. I used the little 12vdc to 5v usb modules off ebay and all running 4 wyze cameras, internet modem, netgear wifi, for about year, no problems. When did have really bad weather, no sun form days, system did go off line, but all rebooted when sun came back.. I skipped ac inverter, run dc straight, saving power! Good luck!

Thanks, this is very much like what I am trying to do at my cabin!

 

[Hedges]

Two, 1A 5V 5W cameras is much less. 10W, assume 12W into the 12V/5V converter, 1A draw from the batteries, 24 Ah/day.
A 12V 100 Ah AGM battery could handle the occasional 3 days without sun at 75% DoD, most nights would only be 15% DoD.
(Size larger or accept shorter run time for the additional power consumed by hotspot)

24 x 12 = 300 Wh/day, a couple 100W panels aimed at morning and afternoon sun should be enough even in winter.
Wired in parallel so two angles is OK, voltage might be low for MPPT so PWM might work better.
Wired in series to work with MPPT, power will be less early and late in the day, a bit more cycling of the battery.

For your other projects, look for larger used PV panels. Check out SanTan Solar for an idea of prices. Sometimes local sellers will be similar, if the freight shipment isn't worthwhile for a small purchase.

 

[Homeless]

Would one of either of these be enough for what I need?

 

[Hedges]

Those should work.

Here's the brand I have:

Sun Xtender PVX-1040T

The SunXtender PVX-1040T boasts industry leading life cycles providing safe, reliable and long lasting power. Recombinant gas SunXtender Deep Cycle AGM Series solar batteries are low resistance, valve regulated lead acid (VRLA) batteries. Non-Spillable maintenance free construction allows...

batteryguys.com

Batteries vary in rated life vs. DoD. I found some info on the lower priced Universal Battery:

Universal Power Group UB121000 AGM Deep Cycle Battery

Universal Power Group UB121000 AGM Deep Cycle Battery

www.deepcyclemarinebattery.com

About 500 cycles to 50% DoD, expect to lose 50% of capacity.

Compare to last page of SunXtender manual which says 1000 cycles to 50% DoD:

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

At twice the price for twice the life, and expecting only 15% DoD for most cycles, the lower priced ones you found may be the best fit.

 

[Homeless]

Those should work.

Here's the brand I have:

Sun Xtender PVX-1040T

The SunXtender PVX-1040T boasts industry leading life cycles providing safe, reliable and long lasting power. Recombinant gas SunXtender Deep Cycle AGM Series solar batteries are low resistance, valve regulated lead acid (VRLA) batteries. Non-Spillable maintenance free construction allows...

batteryguys.com

Batteries vary in rated life vs. DoD. I found some info on the lower priced Universal Battery:

Universal Power Group UB121000 AGM Deep Cycle Battery

Universal Power Group UB121000 AGM Deep Cycle Battery

www.deepcyclemarinebattery.com

About 500 cycles to 50% DoD, expect to lose 50% of capacity.

Compare to last page of SunXtender manual which says 1000 cycles to 50% DoD:

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

At twice the price for twice the life, and expecting only 15% DoD for most cycles, the lower priced ones you found may be the best fit.

Well my brain is smoking from reading all the battery specs so I believe this is what I am going to do. I have three of these Battle Born batteries that are <6 months old. Two of them are in my enclosed trailer and the third one was going to go in my pop up this spring but I believe I will use the spare battery at the cabin.

This battery should work very well for what I need at the moment with the cameras and also has some room to grow before adding another battery. I will use the same solar charger I posted above and the two 100 watt solar panels I already have.

Since I already have the 2 panels, one battery, and the solar controller on hand, I can save the money to re purchase these items to put in my pop up later this spring/summer........kinda putting it on the back burner since I carry a quiet generator with me when using the pop up.

Thanks for all the great information you provided. I have learned some things and will need some additional "coaching" going forward!

Again, many thanks!
Dan (Homeless)