Author Topic: OFF GRID POWER; various thoughts on...  (Read 561110 times)

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Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #900 on: September 29, 2011, 08:11:41 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.

Jeeps are cool :)

I asked the same question a couple years ago with the bent that I'm an old computer guy and found it was cheaper (in the past) to build them then to buy them and what I built was always better then what you could buy for comparable prices.

In solar the case is the same IMHO.  Building it yourself is almost always, if not always, cheaper.  Sunelec had a system much like the one I built though, that was pretty cheap so worth a look to see what they have today.

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #901 on: September 29, 2011, 08:14:31 AM »
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.

*chuckle* My cabin site is within 20 miles of the Canadian border in Zone 5...well in reality I'm Zone 4 for fruit trees because I'm also at 3200 feet in altitude.

I find that the snow often melts or slides off the panels and the only time I see any real covering is in the morning after a cold night there can be a layer of frost that burns off by late morning.  And that was actually at 48 degrees rather then the steeper 63 that they should have been at.  I just found that I was generating plenty of power at the time with them at 48 (probably should put them at 49 though).

Anyway, I'd take a serious look at power production and needs before I tilted them that steeply.

Offline Squirl

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Re: OFF GRID POWER; various thoughts on...
« Reply #902 on: September 29, 2011, 08:50:05 AM »
Jarhead makes a good point of build vs. buy. I came to the same conclusion a few years ago.

There are a few factors that can change the equation.  If you are having it installed, buying the systems prepackaged may save you on labor.  Solar installation electricians can be expensive.  This is most often a factor if looking for the tax credits.

Also you will have to spend a bit of time learning about off grid components and electricity.  This will be a book or two for your collection, and a few from the library on NEC guidelines.

I had a neighbor stop by on my build a little while ago.  He asked if I was going to do my own PV system.  I said of course.  He was surprised and said "but you'll miss out on all the tax credits."  I said who cares about the tax credits.  He told me, "well, plenty of people."  I told him that the added labor cost of a solar installer is far higher than any return on tax credits.  He agreed and left.  I later found out he was a solar installer.

Offline CjAl

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Re: OFF GRID POWER; various thoughts on...
« Reply #903 on: September 29, 2011, 09:36:16 AM »
I'm a poor truck driver. I do everything myself. I work too hard for my money to pay it to someone else if I can do it myself. fortunately (or maybe it's unfortunately) i am usually capable of most tasks some just may need some research.  I have been reading for years so I have a decent base knowledge just not on specific products. I was planning to put a hydro powered generator at my current house. I have a spring fed pond that puts out a good amount of water. unfortunately I have too little head to make a system that would do much more then power a few light bulbs.


and yes Jeeps are very cool but i've spent more on them in my life then anyone ever should. lol

Offline Squirl

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Re: OFF GRID POWER; various thoughts on...
« Reply #904 on: September 29, 2011, 12:36:50 PM »
With hydro you would be surprised.  Even if it is low output, it is constant.  IIRC you are in Texas.  So even if you put out a tiny 25 watts (2 cfl's) an hour that is .6 kilawatts a day 365 days a year.  That is more than some solar systems on here.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #905 on: September 29, 2011, 12:43:06 PM »
DIY'er can take the tax credits on the equipment purchased. Some states, like NM, also do not charge sales taxes on equipment that is used in a solar installation, right form the PV modules down to the nuts, bolts and screws used to mount the equipment and batteries are included.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Squirl

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Re: OFF GRID POWER; various thoughts on...
« Reply #906 on: September 29, 2011, 01:26:13 PM »
This discussion prompted me to look into the incentives since I last started this a few years ago.

It appears they changed the Federal Residential Renewable Energy Tax Credit.
It looks like it even qualifies for second homes and maybe DIY installations.  I have to do more reading.
http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=US37F&re=1&ee=1

http://www.dsireusa.org/documents/Incentives/US37F1.pdf

Has anyone taken this?

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #907 on: September 29, 2011, 02:01:28 PM »
Moi.  On the cabin installation.

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

Offline Rob_O

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Re: OFF GRID POWER; various thoughts on...
« Reply #908 on: September 29, 2011, 03:23:50 PM »
Thanks for that link Squirl. My cabin will be grid powered but I'm going to have a small solar UPS to keep the lights on when the grid goes down and that 30% will pay for the solar panel
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Offline CjAl

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Re: OFF GRID POWER; various thoughts on...
« Reply #909 on: September 29, 2011, 05:47:01 PM »
With hydro you would be surprised.  Even if it is low output, it is constant.  IIRC you are in Texas.  So even if you put out a tiny 25 watts (2 cfl's) an hour that is .6 kilawatts a day 365 days a year.  That is more than some solar systems on here.

not EXACTLY constant. We are over 40" behind on rainfall in southeast tx. My uncles pond is over seven feet low. The lakes in my lake community are not allowing any motorized boats because the water is below the concrete skirt on the dams. My springs are strong but even they couldnt keep up and i havent had water flowing for the last month. Its quite depressing here.

Offline Native_NM

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Re: OFF GRID POWER; various thoughts on...
« Reply #910 on: September 29, 2011, 09:23:29 PM »
Here is one thought:  Schott Poly 230 watt panels are $1.64/watt.  CSI panels are $1.39/watt, and falling.  With the advances in micro-inverters, as well as rack systems, your average guy can start thinking about installing a grid-tie system himself (or herself).  Just for fun I called a solar company here in Albuquerque and asked about the possibility of me doing the install and wiring, and them doing the final tie to the grid, and signing off on the paperwork.  The guy didn't see any problems.  

At $378 a panel (even less for the Chinese panel), plus $175 per panel for the inverter, the cost is $550 per panel.  After adding the additional hardware, permits, and some electrical engineer labor, for about $3.5K one could install 4 panels, or about a 1KW net-meter system.  No batteries required.  After tax credits, net cost is ~$2K.  At my usage, this would reduce my bill by ~15%.  Based on the PNM plan terms, I calculated payback in 8 years.

I have seen some guys on the internet who have built small net-meter systems, and added a small bank of batteries which charge from the main system by AC charger.  A bypass switch is installed which allows the panels to work stand-alone in the event of a power outage.  A transfer switch is used to power the priority circuits.  There is a company in Pennsylvania who has a nice niche market;  power outages are more common in those areas than they are out west.

Another guy wanted to run his place off-grid totally - he just tied his Enphase system into the service panel. Since it was not connected to the grid, it simplified the process dramatically.   During the day he had 120V, and used a battery charger to charge his battery bank which he used at night.  It is more efficient to convert the power at the panel, and then use an AC charger to charge the batteries than it is to carry the DC power to the batteries, then use an inverter to generate 120V.  The higher voltage of the grid-tie panels, in combination with the higher efficiency of the MPTT Enphase inverter, and the fact that much smaller wire can be used, makes it yet another alternative for those with small power needs (off-grid) or somebody just interested in lowering his carbon footprint, or saving  a buck or two over the next 20 years.

Something else for everyone to think about...

New Mexico.  Better than regular Mexico.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #911 on: September 30, 2011, 05:01:18 AM »
.  

  Based on the PNM plan terms, I calculated payback in 8 years.



May be a better payback than most any other investment right now.

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 #912 on: September 30, 2011, 11:56:28 AM »
Is there a reason those csi list only on grid systems under application?

I must admit pv is the system i know the least about. My current property is so heavily wooded its not practical so i researched it much less then hydro and wind

Offline Native_NM

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Re: OFF GRID POWER; various thoughts on...
« Reply #913 on: September 30, 2011, 02:28:06 PM »
The voltage of grid-tie panels is usually twice that of "12 volt" panels, which actually are not 12 volts.  Most 12 volt panels are rated in the high teens.  Under load or partial sunlight they will still put out the 14+ volts needed to charge a 12V battery. 

If you use a high voltage panel with a traditional charge controller, you end up wasting a substantial portion of the watts generated.  An MPPT controller allows for maximum energy harvest from the panel.
New Mexico.  Better than regular Mexico.

Offline CjAl

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Re: OFF GRID POWER; various thoughts on...
« Reply #914 on: September 30, 2011, 03:46:03 PM »
So those panels rated for 20v. With a mppt would be fine for an off grid system? The cheapest 12v panel they list is $2.53/watt


Would it have to be a 12v battery system or could you use a 24v. Araingment?

Offline Native_NM

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Re: OFF GRID POWER; various thoughts on...
« Reply #915 on: September 30, 2011, 03:54:49 PM »
With the proper controller, grid-tie panels are a great off-grid option.  If I had to have a one-panel system, I'd choose a high-voltage 240w panel and a good MPPT controller.  For an off-grid system using a small battery bank, your goal is to maximize the number of amps available to pump into the batteries.  

In the west, some folks report harvesting upwards of 100 amps a day at 12v from a single panel.  You could run an RV indefinitely from a 2-battery system.  We ran an Engel freezer on a job site, and it pulled 2.5 to 3 amps.  The Engel's are expensive, but efficient. Factor in some lighting and a water pump, maybe some TV and radio, and you could live off of 100 amps a day.  We are running a job site trailer on a 200 amp hour bank.  Computers, laser printers, battery chargers, etc.  

I think 100 amps is a stretch, though they did post the controller output, but a quick check of the math validates the numbers.  

The challenge is to ensure you have enough battery capacity also.   It doesn't matter if you generate 100 amps if you cant store it for later use.  I created a spreadsheet that factored usage and sources by hour to ensure a given bank would cover the load.  It has 24 rows (each hour) and then columns for each use and source.  Sources are positive and uses negative.  It assumes a fully charged system at inception.  There is a cell to input max DoD, and it turns the cells yellow when the amps fall below the cutoff.

One can manage the timing of usage to balance the load.  For example, if your battery bank is full and there is still sunlight, that would be a good time to use the inverter (high amps), because the system could recover before night.  The goal is to maximize the timing of sources and uses.  

New Mexico.  Better than regular Mexico.

Offline Native_NM

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Re: OFF GRID POWER; various thoughts on...
« Reply #916 on: September 30, 2011, 03:57:47 PM »
A 24v bank would work fine, as long as you have a 24v inverter. 
New Mexico.  Better than regular Mexico.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #917 on: September 30, 2011, 04:13:54 PM »
Let me toss this into the mix.

IMO, anyone planning an off grid system should go for a 24 VDC based system, unless it is a very small system. Twenty four volt systems can use smaller gauge wires. But to go with a 24 VDC battery bank you would need two of those modules in series, to get the voltage high enough to be able to charge 24 volts. And an MPPT charge controller is really the only way to go*.

Also think hard and long as to what amount of power will be used in the future. I haven't totaled up the values but I do know we have electrical devices in our cabin that we never dreamed of in the year we planned our place. Because the battery bank was planned to be generously over sized we have no issues with running the extras. (More lighting including exterior, blender, electric can opener, electric mattress warmer and more.)

* Lots of things to watch when planning. It's been covered here before, but the charge controller must be able to handle the highest voltage produced by the series panels PLUS a safety factor of 1.56. If the Voc of the two panels was 66.6 volts for example, the CC would need to be rated for a maximum voltage of no less than,  66.6 x 1.56 = 103.896 volts.

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 #918 on: September 30, 2011, 04:30:23 PM »
By "two of those moduals in series" you mean two panels correct? Not two mppt controlers

I would also have a generator for backup if i drew tbe battery banks down too much. My biggest problem.is im in south tx not far off the gulf coast. Air conditioning is mandatory, and lots of it

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #919 on: September 30, 2011, 05:04:29 PM »
PV panel = PV module; somehow I prefer the term module.  ???

For A/C look in mini splits. Sanyo makes some very efficient ones. They can be run from a properly designed/sized PV system. Not a small 12 volt system though.

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 #920 on: September 30, 2011, 06:41:17 PM »
I was already looking at them last week.probably will go that route.

Im also planning a solar hot water/radiant floor system that in the summer could be routed thru shallow wells instead for a sort of pre cooling effect

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #921 on: October 01, 2011, 05:46:22 AM »
Let me toss this into the mix.

IMO, anyone planning an off grid system should go for a 24 VDC based system, unless it is a very small system. Twenty four volt systems can use smaller gauge wires. But to go with a 24 VDC battery bank you would need two of those modules in series, to get the voltage high enough to be able to charge 24 volts. And an MPPT charge controller is really the only way to go*.

Also think hard and long as to what amount of power will be used in the future. I haven't totaled up the values but I do know we have electrical devices in our cabin that we never dreamed of in the year we planned our place. Because the battery bank was planned to be generously over sized we have no issues with running the extras. (More lighting including exterior, blender, electric can opener, electric mattress warmer and more.)

* Lots of things to watch when planning. It's been covered here before, but the charge controller must be able to handle the highest voltage produced by the series panels PLUS a safety factor of 1.56. If the Voc of the two panels was 66.6 volts for example, the CC would need to be rated for a maximum voltage of no less than,  66.6 x 1.56 = 103.896 volts.



This is good advice :)  I find that I use a lot more power then even what I calculated!  Just seems to be a fight really:  use less....use less.....use less...but I use more anyway and watch the batteries drain down to 55% at times...and I'm not even using the freezer yet!

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #922 on: October 01, 2011, 06:04:57 AM »
My calculated daily watt hour usage was 1657 with just the fridge and freezer (by calculated I mean spreadsheet) but using 1700 watt hours per day (fridge and lights only with a little toaster use) drives the batteries down to 12.2v which is about 55% of charge.  So the calculator tells me I could go a few days but I find I'm going only 1.

I've not tried to run too many days without any useable sunlight but I will be trying that out in the near future as winter approaches again. 

I also thought about adding two more batteries (as 10 would be better for planned usage) but I'm bumping right up against 1 year on these ones and am concerned I might be outside the window to add more...if not, then I probably ought to get FOUR more and plan on adding a 4th panel to get me up to 820 watts which in most cases will be enough for the 1020-1340AH bank (though 5 panels would be even better and might be where I go some day).

I don't think I'm too far off mind you, but I think the GCB's don't have the AH capacity they are rated for either...220ah per battery ought to do what I need in 8 batteries but I'm finding that it's more likely a dozen is required.

My plan, however, is to go to a much better battery in the future and to add more panels when I do -- but that day is hopefully 3 to 5 years off yet.

Offline AdironDoc

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Re: OFF GRID POWER; various thoughts on...
« Reply #923 on: October 03, 2011, 08:18:24 AM »
Ok, friends, I need a bit of advice on my solar setup. I've got two 200W 27V panels set up around 55 feet from the house. The way I see it, I have two choices. Build a small shed next to the panels and keep the MPPT charge controller, batteries and inverter there, then run line voltage 55ft to the house. That means building a shed, and, extending my inverter on/off switch wire to reach the house. Second possibility is run the MC4 connectors into 100ft extensions available at Sunelec. I asked the salesman if running 27V over 55-60ft is a better option given potential voltage losses. Salesman said, "why not?". Why not indeed. If that's not a problem, I could keep batteries, and all equipment in the basement meaning less expense and work. What do you guys see as the better option?

Doc

Offline OlJarhead

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Re: OFF GRID POWER; various thoughts on...
« Reply #924 on: October 03, 2011, 08:57:08 AM »
Ok, friends, I need a bit of advice on my solar setup. I've got two 200W 27V panels set up around 55 feet from the house. The way I see it, I have two choices. Build a small shed next to the panels and keep the MPPT charge controller, batteries and inverter there, then run line voltage 55ft to the house. That means building a shed, and, extending my inverter on/off switch wire to reach the house. Second possibility is run the MC4 connectors into 100ft extensions available at Sunelec. I asked the salesman if running 27V over 55-60ft is a better option given potential voltage losses. Salesman said, "why not?". Why not indeed. If that's not a problem, I could keep batteries, and all equipment in the basement meaning less expense and work. What do you guys see as the better option?

Doc
 

Put the panels in series and run them on the 10awg cables from Sunelec -- the 54vdc will be more then enough to carry the current without much loss at all (well within range) to the MPPT controller in the cabin.  This is exactly what I did.

Incidentally 48vdc can run 50 feet on 10awg with <3% loss so at 54+ from 55 feet you are A OK.

As for the higher voltage, don't worry!  You are using an MPPT controller and chances are if you bought a good one then it's likely to take much higher voltages and regulate them down to what is required....that's one of the benefits of using the MPPT style controller.

I'm typically running over 60vdc to my MPPT controller from my panels that are rated at 18.27v (3 in series in my case to give me almost 55vdc) and the Morningstar controller does the rest.

 

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