My Off Grid Cabin System

[HARG Hunter]

We just built our cabin from the ground up.
Concrete slab, 24' x 32' cabin.
The cabin is wired for standard 120v AC current.

Solar Panels: (3) Renogy 100w/12v panels wired in parallel. (Partially wooded area, so we want panels to be separate)
Charge Controller: Renogy Rover Elite 20a MPPT (Connected to panels with 10awg cable)

***Info Below Updated 7-24-23***
Battery Bank: (1) CHINS 12v 200ah LiFePO4 - Connected to the charge controller with 10awg cable. Battery-to-Battery cable is 2awg.
Inverter: Giandel 1500w Pure Sine Wave - 200a inline fuse on positive)

It is wired for 2 circuits:

Circuit #1:
(3) Duplex Outlets that also have USB receptacles for us to charge phones/laptops.
(5) LED recessed lights. 3 of them are 5w, and 2 of them (Outdoor) are 7.2w
Total load on this circuit should be 100w assuming all 5 lights are on, 3 phones are being charged and 2 laptops are being charged.

Circuit #2:
(3) Duplex outlets that are used for misc needs. 1 outlet is for the TV (32" LED TV that only draws 58w
(2) Ceiling Fans with LED lights. (Primarily used at night on low to circulate heat in the winter). Fan draws 50w
(1) Bathroom exhaust fan w/LED Light. Draws 17w

Water Pump:
We have a 12v Water Pressure pump directly connected to the battery bank with a power switch.
This pressures our PEX water supply pipes with water which is drawn from a rain water collection system hooked up to our gutters outside.

Based on projected usage for each light & appliance, we expect to use approx. 1200-1300w per day.

Each circuit terminates to the battery box with a 10ga extension cord plug. (See the "Circuit Connections" photo.
We can plug both circuits into the 1000w Inverter, plug both into the Generator receptacles, or 1 each if we wish.
Inside the battery bank "box" you can see (2) extension cords coming out of the wall. The close-up photo shows in that configuration that we have Circuit #1 plugged into the inverter, and Circuit #2 hooked up to the generator. This gives us flexibility to power the cabin to fit the situation.
In summer, we can run the lights off of the inverter and run a window AC unit off of the generator etc...

This is a young system, so we are still tweaking things, but so far it has worked well, especially giving us the flexibility to run the cabin off of a generator when we are there for longer periods of time or are running high-powered tools.

Current Set-Up cost is approx. $1900

Misc Notes:
Panels are mounted with an adjustable system I made. The frames they are mounting to are treated lumber. The frame is attached to the post with a hinge. The face face our solar south, but the angle is adjustable for each month of the season with holes drilled in aluminum angle iron. I looked up the angles for each month required based on our location her: SOLAR ANGLE CALCULATOR Just scroll down and enter your country, state and approx. nearest city and you're given the angles for each month. I took those angles, simply had my wife move the frame while it was on it's hinge, and marked the angle iron for the drill holes.

All I have to do to adjust the angle is loosen (2) wingnuts, move the brackets to the desired month, and re-tighten the wing nuts. See the "Solar Mounting System" photo for reference. That was when it was only a 2-Panel system, but the angle adjustment system di not change. The adjustable mounting system probably cost me $75 in lumber, angle iron and hardware.

While I'm still learning (Thanks to many members here. You know who you are!), I feel I final have a handle on the system, and it has allowed us to have everything we need in a central Wisconsin off grid hunting cabin. We are able to have more than the essential power we need to be very comfortable instead of roughing it like we used to.

The power company wants $16,000 just to bring power to this location, and that would not include hardware. Plus we'd have a monthly electric bill.
Instead, in the end we'll have spent under $2000 to be energy independent!

Again, I'm no expert, but if you are looking for a similar set-up, I can certainly help you get started if you need someone to help explain things in terms you can understand.

 

[svetz]

Looking Good! Hope you keep blogging your experiences!

Can you provide some additional photos of the tilt system you built? I can see the two bars and holes drilled for the seasonal tilt, but can't make out the pole swivel/attachment.

Also, how is the pole fixed into the ground (concrete?), how did you calculate how much concrete/weight to use? Do you plan on any software monitoring?

What are the future plans? Is this is your test bed for the other panels you mentioned you might add? Why didn't you go roof mounted? Was that specifically to get the tilt feature? If so, how did the economics of the tilt versus adding a couple of extra panels work out?

 

[Hedges]

"Hole for each month's angle" - diminishing returns. Probably 4 angles/year is plenty. I think two is pretty good.

Range of sun angle during the day is greater than across seasons.

200W STC of panels, probably produces 170W PTC.
Into 14V battery is 12A
20A charge controller, could support 50% more PV watts.

If you turned the PV panels to landscape mode, two could tilt up against each other to form an inverted "V"
Another pair would fit next to them.
This would be 400W STC of panels, with peak power within charge controller's range.
Hours of power production would be extended (until shaded by trees.)
It won't reach 2x the Wh/day of present setup, but approach that.
A benefit over all flat (with larger charge controller) is more uniform production over the day (assuming you have loads then, not just at night). If you run loads before sundown, you would start the night at a higher level of of charge.

 

[chrisski]

Looks good.

How much do your laptops pull? I planned to 250 watts which I read somewhere, but charging and playing it came to 150 watts. When that laptop gets used at nighttime, I notice the extra depletion.

For angling, four holes is probably good, but now you’ve got 12 to choose the best four from. I have flat panels on my RV I can adjust and get a measured 30% better output, but its not worth the climb to the top of the RV and the hour of effort it takes to move to those panels since I’m only there for three or four days.

Wondering if you see winds in your location. The mounting frame seems pretty stout and will stand up.

I have flat mounted panels secured to my RV and I have Portable panels that I can angle to the sun, but three of four places I’ve been locally, the wind kicks up and blows the panels over. It’s a shame I get about 1/3rd more output from the 400 watt portable angled panels than I do the 600 watts of flat panels.

It’s a desert area next to the mountains and a couple of hours of before sunrise, the winds start for between 10 to 25 knots, comes out of nowhere and goes for between 15 minutes and a couple hours, and dies before sunrise. I’ve learned to secure these with a cable and this helps somewhat, but the stronger winds still blow them over. I need something better, and it may be filling sandbags for each panel to secure the cable.

 

[HARG Hunter]

Looking Good! Hope you keep blogging your experiences!

Can you provide some additional photos of the tilt system you built? I can see the two bars and holes drilled for the seasonal tilt, but can't make out the pole swivel/attachment.

Also, how is the pole fixed into the ground (concrete?), how did you calculate how much concrete/weight to use? Do you plan on any software monitoring?

What are the future plans? Is this is your test bed for the other panels you mentioned you might add? Why didn't you go roof mounted? Was that specifically to get the tilt feature? If so, how did the economics of the tilt versus adding a couple of extra panels work out?

Thanks. I will do a video tour next time I'm there to give a better idea of everything.

I can post some older pictures of the tilt system when it was just 1 panel.
System didn't change, I just built a bigger frame each time I added a new panel.
It's a very pedestrian system. Simply used an exterior door hinge on top of the frame.

I have the luxury of using equipment from work, so I was able to bring our Bobcat with an auger bit to drill the hole in really rocky soil. The pole is buried 4 feet into the ground with 2-3 bags of concrete.
I also have the conduit attached to the cabin on 1 end and the pole as well for additional support.

The cabin is not positioned to take advantage of a flat mount or even tilted mount.
The panels are facing solar south for the cabin clearing. I plan to remove the 3 trees that are still blocking a bit of sun.

I like the pole mount because accessibility is easy, and it takes 5 minutes to change the tilt with a step ladder.
Basically remove the wing nuts, adjust the tilt and re-attach the wing nuts.

 

[HARG Hunter]

Looks good.

How much do your laptops pull? I planned to 250 watts which I read somewhere, but charging and playing it came to 150 watts. When that laptop gets used at nighttime, I notice the extra depletion.

Thanks. My laptop draws 60w when it's charging.
I only use it to pop in SD cards from our trail cams. Sometimes I use my phone as a hotspot and will do a little internet surfing.

I only run the laptop on it's own battery when I actually use it.
Only plug it in to charge.

It's one of those things where I always make sure it's fully charged before I head to the cabin, so it's rare I even have to charge it when I'm there.

 

[HARG Hunter]

For angling, four holes is probably good, but now you’ve got 12 to choose the best four from. I have flat panels on my RV I can adjust and get a measured 30% better output, but its not worth the climb to the top of the RV and the hour of effort it takes to move to those panels since I’m only there for three or four days.

Wondering if you see winds in your location. The mounting frame seems pretty stout and will stand up.

I basically have it set up to handle 5 date ranges:
Jan/Nov/Dec (30°) Feb/Oct (38°) Mar/Sep (46°) Apr/Aug (54°) May/Jun/Jul (62°)

It was simple to line it up. I printed a protractor and took a sharpie to draw extended lines on card board.
Had my wife hold the frame in place for each date range and I marked the angle iron with a sharpie.
Drilled the holes and bango... Tilt System!

We had a good test as far as wind goes a few weeks ago. We had 40mph+ gusts for a solid 2 days.
When we went up there the next weekend, no problems. I know it's top heavy, but the extra braces really help.
Once the system is at it's final size, I will probably bury a new pole, but have it be a heavy duty metal post.

 

[HARG Hunter]

I need something better, and it may be filling sandbags for each panel to secure the cable.

You may want to consider some type of weight you can fill with water if water is always accessible for you.
Then you can pour out the water when you leave instead of hauling sand bags around with you.
I know it won't kill your gas mileage that much, but we are all here trying to save energy.
Just a thought.

 

[chrisski]

We had a good test as far as wind goes a few weeks ago. We had 40mph+ gusts for a solid 2 days.
When we went up there the next weekend, no problems. I know it's top heavy, but the extra braces really help.

The places I’ve stayed with the sustained night time winds, I’m wondering if a windmill would help with the overnight drain. A couple hours of wind a night could help, but can’t really make a windmill portable, at least not practical for a two night stay.

 

[HARG Hunter]

Can you provide some additional photos of the tilt system you built? I can see the two bars and holes drilled for the seasonal tilt, but can't make out the pole swivel/attachment.

These still might not give you what you were looking for, but this is when I had just built it and kept it in my driveway to test before I took it to the cabin.

The angle irons are fixed permanently to the bottom of the panel frame, then are attached with wingnuts at the post based on the month. The top of the frame is permanently fixed to the top of the post with an exterior heavy duty door hinge.

 

[HARG Hunter]

The places I’ve stayed with the sustained night time winds, I’m wondering if a windmill would help with the overnight drain. A couple hours of wind a night could help, but can’t really make a windmill portable, at least not practical for a two night stay.

That is a great idea. We have a prevailing Westerly wind where we are, so a small wind turbine is a great idea.
It all adds up and that would help on cloudy days in addition to night time.

Just when I thought I had it all figured out, now I have to learn about wind energy!!!
Any "beginner" links for a small system would be great.

 

[HARG Hunter]

If you turned the PV panels to landscape mode, two could tilt up against each other to form an inverted "V"
Another pair would fit next to them.
This would be 400W STC of panels, with peak power within charge controller's range.
Hours of power production would be extended (until shaded by trees.)
It won't reach 2x the Wh/day of present setup, but approach that.
A benefit over all flat (with larger charge controller) is more uniform production over the day (assuming you have loads then, not just at night). If you run loads before sundown, you would start the night at a higher level of of charge.

I'm very intrigued by this.
Not sure why, but I can't visualize this.
Any pics or links you can provide?

 

[Steve_S]

Regarding Wind Turbines..

The Truth About Small Wind Turbines – Solacity Inc.

Installing a small wind turbine? Get the information you need for an informed decision: The good and the bad, just the literal truth to help you choose.

www.solacity.com

 

[Hedges]

You may want to consider some type of weight you can fill with water if water is always accessible for you.
Then you can pour out the water when you leave instead of hauling sand bags around with you.
I know it won't kill your gas mileage that much, but we are all here trying to save energy.
Just a thought.

The sand is to pour on an icy patch if he gets stuck.
Water wouldn't help much.

 

[HARG Hunter]

Regarding Wind Turbines..

The Truth About Small Wind Turbines – Solacity Inc.

Installing a small wind turbine? Get the information you need for an informed decision: The good and the bad, just the literal truth to help you choose.

www.solacity.com

Thanks for the info.
That just talked me out of considering a small wind turbine.
Better off spending that money on over-sizing my solar system.

 

[Hedges]

I'm very intrigued by this.
Not sure why, but I can't visualize this.
Any pics or links you can provide?

Something like this.
You've already got a seasonal tilt.
Instead of one flat array with peak current at Noon, two flat arrays wired in parallel. One peak 9:00 or 10:00 AM, the other peak 3:00 or 4:00 PM.

Two different orientations paralleled onto a single MPPT loses about 2% (according to a test SMA did.)
Panels aimed at morning or afternoon sun get light filtered by a longer path through air, also cut off at sunrise or sunset.
So total Wh available from panels is reduced vs. optimum orientation, but could be a good fit to daytime consumption, charge controller maximum current, or desired battery charge rate.

I have a couple physically separate arrays of different orientations wired in parallel to grid-tie inverters.

 

[Hedges]

Thanks for the info.
That just talked me out of considering a small wind turbine.
Better off spending that money on over-sizing my solar system.

Unless you use the cabin during inclement weather.
If you have a suitable place to erect it, a 60' guyed tower made from conduit is feasible, can be tilted up with a small wind turbine in the 100W to 600W range. That might be a nice boost to 5% production from PV.
Clearance for the guy wires may be a problem if everything is covered with trees.

Of course, portable generator is an alternative. A generator with waste heat used for space heating would be particularly appealing.
Plumb a coolant line from your truck? Imagine a no-drip quick coupling that let you extend the heater hose to a baseboard heater with fan in the cabin.

 

[chrisski]

Regarding Wind Turbines..

The Truth About Small Wind Turbines – Solacity Inc.

Installing a small wind turbine? Get the information you need for an informed decision: The good and the bad, just the literal truth to help you choose.

www.solacity.com

If I could recover 20 to 30 AH (About 250 wh to 350 wh) during these two hours of night winds, that would be a goal.

One of the places had some good sized “small” windmills attached to a satellite fire station for the town. None of those three turbines spun regardless of the wind speed. These windmills must be high maintenance. It’s not only in that place, I see quite a few wind mills that don’t spin.

After my 24 volt upgrade, I will spend some time on what would it take to get 20 to 30 ah.

 

[Ampster]

I see quite a few wind mills that don’t spin.

That may not be an indication that they are all broken. I drive past Altamont Pass all the time and there are lots of windmills there. Depending on the time of day some or many may be running. Some of that is market based and some of that may be wind currents that maybe related to micro elements of location.

 

[svetz]

One of the places had some good sized “small” windmills attached to a satellite fire station for the town. None of those three turbines spun regardless of the wind speed. These windmills must be high maintenance. It’s not only in that place, I see quite a few wind mills that don’t spin.

I used to think that too and maintenance is a reason. But it could also be because of low wind, optimizing based on wind-field pattern, settlement during permitting to turn off certain turbines during migratory seasons for birds or some similar purpose, or curtailment. That last one needs some explanation [ref]:

Wind Curtailment.
An oft-heard criticism of wind farms is that people “drive by them every day while the wind is blowing and the turbines aren’t spinning”. This is true, and it’s often deliberate. The turbine blades are often pitched so that they recover less energy or no energy from the wind, a process commonly referred to as “wind curtailment”. The reason is obvious: if overproduction of wind power results in negative or ultra-low priced energy, one way to avoid paying to get rid of excess energy is shutting down the energy production. So curtailment happens either to prevent or eliminate negative pricing.