Author Topic: OFF GRID POWER; various thoughts on...  (Read 519559 times)

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Offline BiggKidd

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Re: OFF GRID POWER; various thoughts on...
« Reply #1200 on: November 18, 2013, 05:45:56 AM »
Just got tracking info for everything I ordered. According to what they sent everything will be here by friday.  [cool]  When I ordered I got the impression it would be well in to december before everything got here.

  Oh lord I hate mondays, on sunday I take my MS medicine mondays feel like the flu.  >:( To make it worse my girls went to their moms this weekend first time all year and came home with  ..................................... The stomach FLU !

 Hey its november and she got them for the first time in a year and brings them home sick.   >:(  >:(  >:(

  As to installing the panels, I really didn't think this out to well. I just didn't do the math.  d* Putting up the first four panels is no problem just requires a bit of prep work. Its the other 36 planned panels that are causing a problem. The panels roughly measure 40" x 76" x 2" so 40" times 40 panels = one looooooong rack. We are in a small clearing in the middle of the woods. Now taking out trees has always been part of the plan but not that many right away. We are also near the bottom of a hill. So you can imagine the corner I have painted myself into. Another problem I am having is getting a true compass reading. Since my battery bank seems to throw a pretty good magnetic field.

  The biggest problem with taking out the trees is I am not ready to process these. I have been gathering up parts to make a bandsaw mill but haven't started building it yet. A lot of these trees are ones I am planning to use to build a log house.  It will be roughly five years before I am ready to start on the "big house" which is also going up on top of the same hill. Five, six, seven hundred feet away.

 So to make a long story short I think I will place these four panels on a pole mount. That of course means having to move them later. Surely could use some ideas. 

Think I need to start my own thread so I don't  junk this one up with my ineptitude.

Larry

 
A hard life only makes you stronger.

 Larry

Offline upa

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Re: OFF GRID POWER; various thoughts on...
« Reply #1201 on: November 18, 2013, 07:18:49 AM »
Installed and set up my TriMetric meter today and after fully charging the bank it read 101% of charge.

THen after 4 hours of running the cabin (watching TV etc) I see it's reading 94% of charge.  I was happy to see this until I saw the voltage was showing 2.4v which according to Trojan is only 60% of  charge.

I'll have to shut down for the night soon so it will be interesting to see if the batteries increase a little in voltage but I'm a little confused by the 94% right now as it would seem that's not accurate unless I'm not understanding the way it calculates the percentage of charge.

Any ideas?

If I read you battery specs correctly you have around 15kw of stored potential in your 24v battery bank and your trimetric is saying you used 900 watts over 4 hours watching TV , sounds reasonable vs the 6000 watts based on voltage measurement only. I suspect the trimetric measurement via shunt is very accurate at measuring power coming in and out. Basing SOC on voltage alone is not so accurate. Keep in mind that Trojan's SOC table with open circuit voltage values assumes the batteries have been resting for at least 6 hours and it is also meant to be referenced with specific gravity measurement.  If your temperature compensated hydrometer readings are ok, go with what your trimetric says if not, one or more of your cells could be on their way out and they may be dragging the good cells to a dysfunctional level.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #1202 on: November 19, 2013, 04:48:01 AM »
Good post Upa an I agree with what you surmize though need to correct the numbers.  My bank is 12 220AH 2-GCS Golf Cart Batteries in a 24v series/parallel configuration so I've actually only got 660AH of capacity assuming the batteries are still capable of producing max power after 3 years of use and abuse.

Having said that, though, I'm starting to realize a couple things:

1.  Setting the TriMetric meter at 660AH may not be accurate since the batteries are often listed at 210AH as well.  I may change to 630AH to see what it does then.
2.  With the Freezer no longer running I see the generator no longer runs daily.  It ran the 14th and the 16th and may run today but it's possible it won't if the sun comes out nice and strong.
3.  Battery bank read 25.1v when I arrived around 6PM last night and drew down to 24.6/24.5 by the time I went to bed around 9PM (I was watching TV).  This morning some 8 hrs later the batteries were at 24.6/24.5 still.  Clearly leaving the inverter in sleep mode and only running the fridge and composter fan uses very little power and I should no longer have to worry about leaving for weekends etc. but more interestingly was the battery bank reading because it demonstrates that just because a voltage is recorded does not mean that you have a specific percentage remaining on the batteries.  It takes more factors in order to determine that and there's a lesson there.

Oh and yes, the TriMetric meter has leads that run to both sides of the shunt as well as the battery bank (one side).

Offline upa

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Re: OFF GRID POWER; various thoughts on...
« Reply #1203 on: November 19, 2013, 11:12:12 AM »
I suspect you are very under panelled for the size of battery bank and it is more apparent now that the sun is less seasonally helpful :(. I think I read somewhere your array was 600 watts, which with some quick math and assuming optimal conditions would only provide a 2-3% charge rate on a 660 amp/hr 24 volt bank. That would explain why your generator is starting up every day especially with the presence of a refrigeration load. Generally a c/10 or 10% charge rate is more desirable in a balanced system and this would probably represent a 2400 watt array. I  think even doubling your array to 1200 watts would help quite abit, likely borderline in the depths of winter but likely ok in summer. If you have any money left in your budget I would look at more panels since they are fairly inexpensive at the moment.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #1204 on: November 19, 2013, 03:02:41 PM »
In this case the system was build as a 12v system with 660AH at 12v and 615watts of solar at about 60v (MPPT controller), then I added 2 more batteries to take the bank to 880AH and the panels were doing fine there but when I converted to 24v I also added 4 more batteries taking me to 660AH (would have been 1320@12vdc) and really need another panel.

At the moment the fridge isn't an issue and the usage I have is working out nicely.  It was the addition of the freezer that caused the headache as it was just a little too much with me also running lights and the TV etc.

So, today when I left the bank was at 24.4vdc and the sun likely brought it back up enough to last another day ;)  The gen hasn't run since Saturday now and while it may run tonight when I get in and start watching TV it also may not.

So I think I'm ok now but if I want to run the freezer again I'll need more solar charging and likely a new bank of batteries with a little more capacity.

Offline BiggKidd

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Re: OFF GRID POWER; various thoughts on...
« Reply #1205 on: November 21, 2013, 10:15:22 AM »
Thats Great,

Any day (s) without the genset running are good days.   [cool]

PS My panels just got delivered.

A hard life only makes you stronger.

 Larry

Offline MNJon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1206 on: November 22, 2013, 07:30:30 AM »
Hi again fellow CPR'ers. I am now living full time in my off grid home and have a few questions for the experts. We have finally completed most of the work required to prepare for a Northern Minnesota winter so now I can work on a few pressing but non critical issues. POWER!! We have been running two generators for 100% of our power needs. A 2K Champion inverter is our primary source 90% and a Champion 9K fills in the balance. I have them wired to two different panels with a transfer switch connecting them. That way I can continually run the house off the 2K, fire up the 9K when we need to run the well pump and shut it back down. If we want to run the entire house off the 9K to run the microwave, hairdryer and other high wattage devices we just flip the transfer switch.

My question REFRIGERATION! Until now we have simply used coolers, yes coolers for a family of 6! My wife has been very patient but is ready for a real fridge. We had a small fridge but it was too much of a load on the 2K genny with everything else. I want to try two things. Since it is 7 degrees outside right now I want to cut a hole in the top and run a 1.5 PVC fresh air intake into the fridge, this should help substantially through March to reduce the electrical load. Secondly, I want to setup solar dedicated to the fridge. How do I calculate my needs for both PV collection and battery storage? I would also like to change the compressor to a Danfoss BD35F.

Thoughts?

Thanks in advance-Jon

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1207 on: November 22, 2013, 10:45:09 AM »
I don't think the piece of pvc pipe will have a great effect unless the air exchange is fan driven. No proof, just a thought.

Solar for fridge. You have to start with the fridge and the power it consumes to work and give satisfactory results. The Danfoss would be a good compressor for a 12 to 24 VDC system. Would the BD35 have the capacity for the size of fridge you have in mind? I know they have programming that is used to suit them best to various configurations.

If I was going to the trouble of adapting a Danfoss I would also investigate how easy/difficult it would be to have the waste heat from the compressor stay in the house in cool weather but be vented outside in warm weather. We do that with a conventional refrigerator and it does make a noticeable difference in both winter and summer.

So anyhow once you know the watt-hours the fridge will use in a 24 hour period you can calculate the battery capacity. Keep in mind batteries are less efficient in the cold, how many days of cloudy weather you want to cover and the maximum depth of discharge on the batteries.

Once the battery bank size is known, with the local good sun hours known the size of the PV array can be calculated. Other variables such as choosing a MPPT charge controller over a PWM type have to be looked at and possibly matched to the specs of PV panels used.

But start with the watt hours of power needed.

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

Offline MNJon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1208 on: November 22, 2013, 04:52:50 PM »
Don-  Im not sure how much effect the cold air intake will have either to be exact. I though about wiring a dc computer fan to a small pv panel to run during the day. Just based on my experience living in Minnesota I know cold air rushes in like a waterfall though an opening. I was just installing a fresh air intake for my Lopi Endeavor and when the 3" line was laying on the floor it felt like it was being forced in by a blower.

Im not sure about the effectiveness of the Danfoss BD35F, I just thought it would make sense if I had a dedicated panel and battery bank for the fridge to convert to DC and drop the inverter from the system. I dont even have the fridge yet, so once I buy one and know the draw I will start there.

Offline DaveOrr

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Re: OFF GRID POWER; various thoughts on...
« Reply #1209 on: November 22, 2013, 05:37:09 PM »
I am going to run a propane fridge at my cabin.
No worrying about running my batteries down and the things will run a long time off a 100# tank. ;)
Dave's Arctic Cabin: www.anglersparadise.ca

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1210 on: November 22, 2013, 07:17:48 PM »
Propane fridges are another option. Ours does work well. When we bought it PV panels cost double what they do today. The propane fridge costs a little more today, but then batteries also cost a wee bit more today.

The Danfoss compressor sure is efficient and I like them.

The regular home refrigerator can be had in some fairly efficient models for much less than a propane fridge of equal size. But you have to run AC.

Several different ways to go... personally if I was doing the fridge thing all over today I lean heavily towards more PV and batteries and a regular residential refrigerator. Although it would also then be nice to have an auto start generator setup to cover things just in case the weather went solar crappy for a week.
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 #1211 on: November 24, 2013, 05:29:25 AM »
I use a Danby fridge with no freezer.  IT uses less energy and I have the option of running a freezer if I really need one (in my thread I mention that I've turned mine off so I don't really need it and it takes too much power to run).

IN the future I'll get a bigger battery bank and more panels and run the freezer too.

Offline MNJon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1212 on: November 27, 2013, 06:44:28 AM »
I think I am going to start with an older used fridge. That way if I cut a hole in it to pipe in the 5 degree air from outside all winter and it is not successful I am not really out much. I just cannot justify an LP unit. I think I would rather spend the money on an efficient standard unit and pv system for it.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #1213 on: November 27, 2013, 12:42:38 PM »
Yes any day the gen doesn't run is a good day!  Specially when the heaters are running!

Got this from Bogart:
Quote
Hello again, Erik
Your're reading the percent right. But keep in mind that battery companies estimate the "capacity" of their batteries higher than is realistic. So 91% may be optimistic.  The main value of this is that from one day to the next you can see your relative battery usage.  And yes, voltage is a very poor guide to how full batteries are-- except when they are very full-- or very empty.

Also, I wouuldn't worry about getting the exact capacity entered in the meter-- the really useful part of the percent is to be able to compare your relative usage, (as I said). If you usually get down to 85% or so (say) and then one day it goes down to 70%, that tells you that you are about twice as far down as you were before.

As to voltage for turning on generator-- probably 23.8 could be reasonable.  Even this might be a little early if you voltage was lower because of a high load you just had.
But when you get down to about 22.5 volts, then the volts number becomes significant to tell you that you are really low on power. Above 24V voltage is a very poor guide.

So I think setting the bank to 630 might be more realistic and I did this.  I've got the switch set to 23.8v as a safe bet but I might lower it to 23.5v to see how that works out.

On a side note the boys were using the skill saw this past weekend when the gen wasn't running and the inverter didn't care one bit ;)  The cabin was powered easily as well as the saw so I'm pretty happy with my 4k inverter now :)

Offline BiggKidd

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Re: OFF GRID POWER; various thoughts on...
« Reply #1214 on: December 17, 2013, 07:13:14 PM »
Finally got my 4 little panels up today.



A slow start to going solar with only 1200 watts. I also have six of the HF 45w kits that we have had a few years now.

 Now I am still waiting on the combiner box to show up then I can hook it all together. I was able to keep some of the tilt adjustable I can adjust between 35 and 55 degrees. The tall front posts do create a small bit of shading but I think (hope) its worth it. In the picture the panels are at 51 degrees.

Larry
A hard life only makes you stronger.

 Larry

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1215 on: January 03, 2014, 04:31:28 PM »
There are many things that we take for granted when we live connected to the power grid. One is the maintenance of the batteries in out motorcycles, ATV's etc. If the ATV or whatever gets taken back to where the grid is available connecting to a charger of some kind requires little thought. There have been 2 off grid approaches I have used; taking the battery home over winter and using a small PV panel to maintain the charge. Taking the battery home is a pita. falling tree branches do bad things to small pv panels.


We have an Outback charge controller. They have an auxiliary function. One of the options on the AUX menu is called float. When the main battery bank has gone through the bulk and absorb stages it goes into float charge. With the float function engaged a device can be switched on. I chose to have the float function activate a solid state relay switch.

The SSR switch is connected to the on-off remote on the Outback inverter. So when the CC goes into float the inverter is switched on. We make sure that when we leave all lights, fans, pumps, etc are all turned off.

This time of year when the cabin is left unoccupied the charge system goes through a brief daily bulk charge, a one hour absorb charge and then into float. On an average day float lasts for 3 hours, maybe 3.5 hours.

In the barn I leave a 2 amp battery charger connected to the ATV battery. It is plugged into a timer that is plugged into 120 VAC power. When the CC is asleep, in bulk or in absorb the timer and battery charger are off. When the CC is in float the timer is running. When the timer clicks into "on" mode the battery charger begins to charge the battery. It is set to allow battery charging for 2 hours every 12 hours of float time; 2 hours every 3 to 4 days.

I hooked it up November first. So far it has worked well. We went up just after C-mas. The ATV cranked over and started on one tap of the start button. Left disconnected overnight the voltage in the AM was 12.65; full.

It works for me and beats dragging the battery home.  Plus the SSR came out of a surplus box.
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 #1216 on: January 12, 2014, 01:44:56 PM »
I have long resisted the urge to buy a battery monitor for the cabin PV system. Partly out of my own parsimonious nature and partly because sp gr readings are a very accurate method of telling not only battery state of charge but the health of individual cells. However, now because of a top from one of the members here, I now have an Outback Flexnet DC and I got it at a very good price. The ebay vendor has one left although for a slightly higher price than what I paid.

When I get it installed and hooked up I'll report back. Use requires an Outback Mate which I have had since the system was placed into service.

It comes with the needed twisted pair wires and a Cat5 cable. In addition it does require at least one 500 amp shunt.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline upa

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Re: OFF GRID POWER; various thoughts on...
« Reply #1217 on: January 13, 2014, 06:46:17 AM »
My system has only been up a couple of months but I am really starting to warm up to the flexnet monitor's  utility. I have to admit I was a little skeptical initially on how useful it would be and I don't think it will entirely replace periodic checks of specific gravity, but on the whole it seems like a reasonably accurate measure of the energy that comes in and out of the battery. The connected mate can report all sorts of useful information from SOC to specific real time/historical amp/wattage draw and replacement. What I probably like most is that on the mate 3 the battery health can also be simply represented by just 3 brightly colored LEDs that you can clearly see from across the house(now that is mounted in the dining room not the power shed). This is brilliant for my wife who could care less what an amp is but has no problem appreciating green is good, yellow is caution(less than 80% SOC)  and if she sees red she needs to get my attention  :)

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #1218 on: January 13, 2014, 10:01:03 AM »
Funny that you mention that.  I tend to use mine more as a voltage meter then a % of charge meter though I do look at that too.  Now that I have it though, and understand what I'm looking at a little more I really like having it.  I must also admit that I love the Magnum auto start switch too@!  Specially since I can dial it up or down depending on my needs or time of day.

For example, when I know the load will be light and I'll be away I tend to set it at 23.0vdc which is about 80% on the % meter (really depends on loads and use ove a period of time and not specifically the voltage itself) whereas when I know the load will be heavier and I'll be using a lot of power in the evenings I set the switch to start at 23.5 to 23.8vdc and make sure the generator will come on to run it's 5 hours when I'm using the most power.  That way if the sun didn't come out and the batteries are around 24.2vdc when I arrive at the cabin the generator will kick on shortly after I fire up my network and/or TV and will power the cabin while giving the batteries a good charge.

One thing I also do is set my inverter to sleep mode when I am gone.  I love this feature because it kicks the usage down to between 5 and 20 watts and only kicks on to full power when something like the refrigerator needs it.  This can make the differnce between the generator running daily on cloudy days (or every other day) to not running at all for a week.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1219 on: January 13, 2014, 10:34:59 AM »
Quote
I also do is set my inverter to sleep mode when I am gone.

Why only when you are away?  Just curious.  ???  We leave the inverter in search mode all the time so it sleeps when not needed. That amounts to most of the daylight hours of any typical day at the cabin.
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 #1220 on: January 13, 2014, 07:42:08 PM »
Why only when you are away?  Just curious.  ???  We leave the inverter in search mode all the time so it sleeps when not needed. That amounts to most of the daylight hours of any typical day at the cabin.

Because if it's in sleep mode the answering machine won't kick it on when someone tries to call me when I'm out working around the place (and have no cell coverage)...I discovered that the answering machine doesn't draw enough wattage to cause the inverter to 'wake up' so I miss calls and messages if I don't have it on when I am not there.

On the otherhand I flip it to sleep at night and when I am away.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1221 on: September 15, 2014, 02:30:18 PM »
This summer I needed to replace a DC motor speed control for our RCH ceiling fan due to a lightning hit. They now sell at about $100.

I found a speed control on ebay for less than $8. The catch... ships from China and will not fit inside a std wall box. I took a chance and risked a total of $7.41 including shipping. Price today may be a little more.

Obtaining a working model was a bit of a task. The first one arrived with a really cold solder joint; a MOSFET was loose on the board. They shipped a replacement @ n/c. Each shipment was slooow; about 20 days from China. The second arrived with the srew that hold a heatsink to the MOSFET cross threaded and loose. The third one was the charm and arrived in great shape. I connected it to the fan Friday night. It works fine. The speed is adjustable from just above stall to full speed. It just looks funky.

The bonus is the other two controls also work after I re-soldered the one and found a tiny screw to repair the other.

The amount of time it took was a disappointment, but their customer service was good enough for the price paid.


When I get around to it I'll see how they work as a dimmer for 12 VDC LED's. 

I chose this one because of the high frequency. There are lower frequency ones that are a little cheaper but there is a chance of hearing a buzz.  Oh... in my application it also ran very cool as well as quiet.
Just because something has been done and has not failed, doesn’t mean it is good design.

shohel1000

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Re: OFF GRID POWER; various thoughts on...
« Reply #1222 on: September 24, 2014, 04:12:41 AM »
 :( I am not satisfied with this forum...

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1223 on: September 24, 2014, 04:32:54 AM »
spammers usually are
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline rick91351

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Re: OFF GRID POWER; various thoughts on...
« Reply #1224 on: September 24, 2014, 06:06:05 AM »
:( I am not satisfied with this forum...

Strange post and it is not even a full moon........  Another group I follow went in the toilet this week.  Attacked by four or five most likely one that is trying to bust it up....  Doing a great job of it.....

You Administrators do a remarkable job with this group.  We have had our issues but pretty dog gone good info at the grass roots level. 
   
Proverbs 24:3-5 Through wisdom is an house builded; an by understanding it is established.  4 And by knowledge shall the chambers be filled with all precious and pleasant riches.  5 A wise man is strong; yea, a man of knowledge increaseth strength.

 

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