Author Topic: OFF GRID POWER; various thoughts on...  (Read 561166 times)

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Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #875 on: August 23, 2011, 03:14:35 PM »
Am I correct in taking the 65% to mean you drew the batteries down to have 65% capacity remaining? That's not bad but doesn't give much wiggle room for clouds if that was a typical single day.

Regarding the refrigerator. One thing I've noticed with our propane fridge is that while we are using the cabin the fridge maintains 35 to 40 F on our number 5.5, but when we leave the cabin for several days the fridge will freeze some things. So then our number 4.5 seems to work best. It would be interesting to see how the temperature in yours runs.





Yes 65% remaining.  The lowest I've seen the system get to so far is 12.2vdc which I believe (I'll have to check) is around 50%.

Our fridge seems to run cold enough around 4.5 on the setting and that can cause some ice formation (droplets) on the back wall of the unit (inside it of course)...when we leave we adjust to 2.5-3 and that keeps a couple gallons of water quite cool/cold.

I could shut it off when we're gone but I want to see just how the system performs.

As for battery power, I'm concerned also.  I used the calculator to plan the system and my calcs suggest 880ah is enough power to run the fridge and lights the way we do and not draw the system down but it appears to be incorrect.  I'd not really expect an overnight drop of greater then 20% if it is to last 3 days without sun...let alone 4!  So, perhaps 440ah of battery power ought to be added before it's been a year to ensure I can indeed run the freezer and fridge full time as I have not even tried that yet!

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #876 on: August 23, 2011, 03:23:44 PM »
12.2 is about 50% with a big BUT.... but that can be thrown off by recent battery charges or discharges and needs temperature correction. Hydrometer is best, but needs temp correction too.

As far as fridge temperature, leaving a few gallons in it if there is not much food is a good idea; helps keep the cool working right. 40 degrees or lower is needed for best food preservation, BTW.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #877 on: August 23, 2011, 03:32:34 PM »
12.2 is about 50% with a big BUT.... but that can be thrown off by recent battery charges or discharges and needs temperature correction. Hydrometer is best, but needs temp correction too.

As far as fridge temperature, leaving a few gallons in it if there is not much food is a good idea; helps keep the cool working right. 40 degrees or lower is needed for best food preservation, BTW.



Thanks Don,

I have to get a Hydrometer pretty soon!  I've been relying on gauges and meters so far but it's a learning curve.

This past weekend I had a strange thing occur:  the 60a breaker on the disco box that the panels are run to tripped.  THe midnight solar 60amp breaker did not trip but this one did  ???  Then the MPPT controller showed a Green and Yellow LED which should mean that I was down to 60% of charge but I knew that wasn't right since everything said 100% otherwise.  So I reset the MPPT controller and it went back green...BUT it was during the main part of the day when I normally get a lot of my charging...so I double checked and the panels were giving decent power and the controller was indeed charging the string...something isn't right.

I logged into the box via serial cable becuase the Ethernet connection would not work...so at this point I'm not sure what happened.

Daily I'm getting a HVD alarm (High Voltage Disconnect) but I'm not seeing voltages high enough to trip that...another thing to try to resolve.

Lastly, my well solar tripped also!  My Xantrex C40 was not running and the batteries (two group 27's in series) were dead!  One was at 2.2vdc and the other was at 8vdc...something smells.

I checked the system and couldn't figure it out, removed and replaced the batteries (I had two spares) and everything worked fine again...then the sureflo pump shorted out (I think) and the bank went to 1.0vdc!!!  Yikes!  I disco'd the pump and the batteries were back to 25.6vdc.

So, I came home and ordered a new Surflow pump and did a little more of this:  ???

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #878 on: August 26, 2011, 10:31:47 AM »
What about night time temps versus day time temps?

Currently it can get to 85+ during the day at the cabin but drop to 40 at night...everything cools down.

So, if I figure my battery banks out at 40 degrees I suspect I'll need more batteries.  No?

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #879 on: August 26, 2011, 10:54:40 AM »
Our batteries are cool to cold all the time. In summer the cases may warm on a hot day but the fluid still measures colder. EG: When I checked the sp gr about a month ago when we were having 85 F highs in the afternoon, the fluid was still only about 62 F. Very few actual hours of the hot summer day have the high air temps; most of the day/night is spent below 65. I don't measure much in the winter but the last time I did the fluid was hovering somewhere around freezing. So yes, that does diminish what's available for use.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #880 on: August 26, 2011, 11:13:04 AM »
Now if I was to dig another, bigger hole in the ground and have the batteries down there, they would stay warmer in the winter.  :D  Perhaps the charging and discharging might even produce some heat that could be trapped? Probably not worth my effort though considering winter use is only for a few days at a time and a couple weeks apart.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #881 on: August 26, 2011, 11:33:41 AM »
This is actually why I decided to build the porch and put the batteries inside of it.  I can use the windows for solar heating and found that even without insulation I can keep the porch 10-12 degrees warmer then outside.  When it's -10 degrees that's probably a good thing!

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #882 on: September 16, 2011, 09:14:18 AM »
Question for Dave Sparks....

For someone with an Outback FM60 charge controller and an Outback VFX 3524(M) inverter, what would you suggest as spares? Listed from most likely to less likely to be required.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #883 on: September 16, 2011, 11:04:05 AM »
Any MPPT controller needs a spare MPPT controller for offgrid unless you are willing to rewire the array for a cheaper non-MPPT controller while Outback repairs your unit. The 45A Morningstar MPPT is pretty inexpensive and I have a spare one along with the XW gear that I only install these days. Their 600V controller has really made my long distance array runs easy.

An inexpensive Inverter/charger can be bout used or?

I go thru all this with some of my real remote customers who live full time in offgrid homes. It often comes down to how their system and how "they" want to live during a failure in the depth of winter. I have one guy who is a Merchant Marine guy who is gone long periods and just turns off his electric reefer and uses a propane unit. No worries about bad weather with propane.  Everyone offgrid fulltime basically has to have strategy for how they will deal with it.

"It always fails in winter and at night"  OLD Sailor......
How was your summer Don?
"we go where the power lines don't"

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #884 on: September 16, 2011, 11:48:52 AM »
Thanks Dave.  I do have a square wave 900 watt inverter that is there for emergencies. But I haven't got anything to handle the charging chores as yet.

My summer? Well except for...
1.  having the largest forest fire in recorded NM history come as close as 1.5 miles to the cabin,
2.  having my jaw wired shut for a big chunk of the summer,
... it was a fine summer.  :)

Since the fire missed us and my jaw works reasonably well now I guess I should not complain at all.

Heading back up in a few hours to thin some more trees.



Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #885 on: September 17, 2011, 05:03:47 AM »
Have a good trip and yes we heard about all the fires in the Southwest. I think that they are our version of the weather that the Southeast calls the "mean season". 

If you look at your array, you may be able to figure an easy way to use temporary jumpers to sub a small controller in while the CC is in for repair. Most likely the only thing that would cause this with Outback would be lightning or the fan.
"we go where the power lines don't"

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #886 on: September 18, 2011, 09:16:11 AM »
I've heard about the fan.....

It would be fairly easy to re connect two of the three modules to use in parallel with a cheap emergency controller. I should probably act to be covered "just in case". Hopefully I did a good job on the asrrestor and dual ground rods. We get lots of lightning.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #887 on: September 18, 2011, 07:53:46 PM »
I'm still struggling with my Morningstar MPPT 60amp (TriStar) charge controller.  It works, but every evening it alarms out with a 'battery high voltage' alarm and then resets the controller.

I've had NO luck getting help from Morningstar and the logs do not show a high voltage on the batteries either.  Very strange.

Also, I cannot change the time on it from GMT -- I'd much rather it recorded using my time zone rather then GMT....there are other items I'm not as thrilled about but after paying the $500 for it I'm not going to change it out with an outback any time soon :(  But I doubt I'll buy another.

I should clarify though with this: other wise it seems to work perfectly   d*

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #888 on: September 18, 2011, 08:27:06 PM »
... XW gear that I only install these days. Their 600V controller has really made my long distance array runs easy.


Ouch!!!  $$$  Pricey but I can see how very nice one would be.  :)  I could triple the number of PV modules and pass the power through the same wiring up the 325 feet of hill.

« Last Edit: September 18, 2011, 08:45:20 PM by MountainDon »
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline PorkChopsMmm

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Re: OFF GRID POWER; various thoughts on...
« Reply #889 on: September 26, 2011, 08:17:43 AM »
Don, quick question. Others, feel free to chime in. Can you provide the vendor for your Uni-rac pole mount? Below is a link to a thread on Northern Arizona Wind and Sun that details and upgrade I am making from a 12V solar setup to 48V. In this move I would like to pole mount my  6 240W panels. I called Solar Biz and they told me that every rack that holds panels on top of the pole mount is custom made and that I would need to provide specifications on where the holes are located on my panels.

My problem is that I have some panels from different vendors, but all with similar amps and volts. I am looking for the bare aluminum struts or thereabouts so I can just drill holes for the mounting or use generic brackets that clip to the struts. Any suggestions?

http://www.wind-sun.com/ForumVB/showthread.php?p=97545#post97545

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #890 on: September 26, 2011, 09:12:52 AM »
I guess I was lucky. I had all new panels, three of the same. The kit I needed was ordered thru Affordable Solar in Albuquerque. They had the rack kit from Uni-Rac in a day, maybe it was two. Uni-Rac is also in ABQ and the kit was available right away.

I don't remember the exact details of how the panels mounted, but there were clips that fitted into a groove in the extruded aluminum bars that connected to the cross arm. I don't remember any more than that.  I'll look through my photos later today and see what I have that might help.

It would be nice to be able to buy just the top mount.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline PorkChopsMmm

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Re: OFF GRID POWER; various thoughts on...
« Reply #891 on: September 26, 2011, 09:50:12 AM »
Yes, true. If I could just buy the top mount I would. I think I could make my own bracing using Unistrut or the other type bracket systems they sell at Lowes, Home Depot, etc.

With pricing from these companies it is looking like the mount with bracing would be ~$1,100, without the pole, concrete, etc. I am wondering if I could build my own tilt-able, but not turn-able, solar mount. Sort of like this one but larger/stronger...



Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #892 on: September 26, 2011, 10:40:53 AM »
Ojlarhead had a rack made.

One nice thing about an off the shelf rack is that it is designed for the wind loads that can come along with the large array.

I think this could be doable with an off shelf array, but you may need to be willing to do some jury rigging, changes, on your own dime and responsibility.

But first a thought. have you gone through the Unirac sizing charts? I'd look to see if the two types of panels you have are similar enough that by some fluke of chance they use the same kit for both panel types. IIRC you said you have three of one and three of another. See if 6 of one type uses the same kit as six of the other.

Or, the modification route... get a 3 vertical x 3 side by side type for the larger of the panels that you have. That type of array frame uses a single aluminum pipe cross tee with a pair of the long bars for each set of three modules. You should be able to make the second set fit. You may have to drill new holes and could void any warranty. You also would not want to drill through in a wrong spot.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline CjAl

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Re: OFF GRID POWER; various thoughts on...
« Reply #893 on: September 26, 2011, 11:30:51 AM »
This has been a great thread.

Offline Squirl

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Re: OFF GRID POWER; various thoughts on...
« Reply #894 on: September 26, 2011, 11:36:55 AM »
There are so many ways to skin this cat.

I have seen some build of PT wood and concrete in a design similar to what you posted.

Also many of the top racks I see are built with angle iron and bolted or welded together.

If you have set on a pole mounted system you may find this helpful.

http://homepower.com/view/?file=HP108_pg28_Schwartz&pdf=1

A little reading on tilt vs. no tilt.

http://homepower.com/article/?file=HP139_pg32_Methods

A little reading on ground mounts.

http://homepower.com/view/?file=HP144_pg114_McPheeters

Offline PorkChopsMmm

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Re: OFF GRID POWER; various thoughts on...
« Reply #895 on: September 29, 2011, 05:31:13 AM »
Squirl, thank you for the links. Getting a pole mount up and running before the winter is looking like less of a possibility. I think I will buy a frame out of PT lumber for my 3 new panels, similar to what is already built for the other 3 panels, and attempt to raise and anchor them. I want a pretty aggressive angle, 85 degrees or so, to dump snow in the winter time.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #896 on: September 29, 2011, 05:44:13 AM »
Squirl, thank you for the links. Getting a pole mount up and running before the winter is looking like less of a possibility. I think I will buy a frame out of PT lumber for my 3 new panels, similar to what is already built for the other 3 panels, and attempt to raise and anchor them. I want a pretty aggressive angle, 85 degrees or so, to dump snow in the winter time.

The angle of the panels should match your latitude or +/- 15% of said latitude.  IN the winter my panels will be set to 63 degrees (90 being straight up and down and 0 being parallel to the deck), in the fall and spring 48 degrees and summer 33 degrees.

You can use a 4" sch40 pole sunk 3' into the ground and concreted there with a 1 1/2" angle iron frame like I did and it won't blow over easily!  My neighbor built mine for under $400!

Offline PorkChopsMmm

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Re: OFF GRID POWER; various thoughts on...
« Reply #897 on: September 29, 2011, 06:00:33 AM »
The angle of the panels should match your latitude or +/- 15% of said latitude.  IN the winter my panels will be set to 63 degrees (90 being straight up and down and 0 being parallel to the deck), in the fall and spring 48 degrees and summer 33 degrees.

You can use a 4" sch40 pole sunk 3' into the ground and concreted there with a 1 1/2" angle iron frame like I did and it won't blow over easily!  My neighbor built mine for under $400!

That theoretically works but I am up in zone 5 that sees lots of feet of snow. The snow won't melt or blow off if it is at a 63 degree angle. While you lose efficiency with the 85 degree tilt you can actually capture sun because your panels aren't covered in snow. I had to go brush down my panels a couple times a day when it was snowing last winter.

Offline Squirl

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Re: OFF GRID POWER; various thoughts on...
« Reply #898 on: September 29, 2011, 07:00:41 AM »
I will share the idea I've been kicking around in my head for a while.  I believe I saw something similar in home power or build it solar, but I can't remember exactly where.

I would build it close to the one in the third homepower article.  The difference would be that I would place the sonotubes closer together.  This way the "joist" for lack of a better word that runs from the bottom to the top could connect directly to the post.  I would connect them through the largest grade 8 galvanized bolt that I could fit.  A lock nut with the plastic would give me enough tension on the bolt but allow the "joist" to rotate.  I would then leave about 2-3 ft of empty space at the top of the "joist".  I would drill holes along the length of the "joist" and the taller poles. I would use a clevis pin or bolt and simple raise and lower the "joists" to adjust their angle at different times of the year.  I would of course have some bracing between members.  The advantage of this is it uses smaller members to carry the wind and snow forces across a larger area.  The smaller pieces can be found a lot easier from big box retailers in things like fencing posts and galvanized pipe.  I have also seen these built with pressure treated wood. Just be cautious if touching dissimilar metals together. 

I agree with Jarhead.  The nice thing about a ground mount is that it is very easy to go out with a broom and dust off your panels.  You will be sacrificing a lot of power at that angle.  I am also in the northern part of zone 5.  Is it really worth it to brush them off in the middle of a snow storm?  You don't get almost any power while it is snowing anyway.  Are you getting the lake effect snow of 4-5 ft per storm?

Offline CjAl

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Re: OFF GRID POWER; various thoughts on...
« Reply #899 on: September 29, 2011, 07:02:02 AM »
I have been dreaming of being off grid for years. I was looking at some outback equpment a while back. Does anyone have links for the cheapest sources?

Also what are your opinions on wether to buy it all assembled vs buying it seperatly and assembling it?

I would like to not have to worry about the dual invertors and stick with 120v. I do alot of jeep building and use 220 in the shop but i guess i can run a generator for that. I have a friend imigrating from australia and im trying to get him to make enough room in his container to bring me a lister motor for running a generator.

 

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